- mbed-tls - lists.trustedfirmware.org

by Xavier Del Campo Romero

I want to connect an ESP32 to a DTLS server using mbedtls' dtls_server demo. The code I used for the client is very similar to the dtls_client example, but is unable to finish the handshake process for some reason. According to Wireshark, the client is not responding to the "Server hello done" frame, causing a timeout that makes the server to send the certificate again and again until it gives up the connection. The dtls_client demo works correctly on the computer, but not on the ESP32. Has anyone tested DTLS on the ESP32? I have attached the following files for further reference: - dtls_esp32.pcapng: Wireshark file with the DTLS packets between client and server. - mbedtls.tar.bz2: compressed (> 7k lines) plain text log as reported by the board. On line 7131, where the last message from the server is received, it looks like the client never receives the whole message, so it never reaches the "Server hello done" state. Could anyone please confirm this? - dtls.c: client source code. Slightly modified from the dtls_client example. Thank you very much for your help. Xavi

5 years, 2 months

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Re: [mbed-tls] Feedback sought on a new PSA Crypto driver interface

by Quach, Brian

Hi, I was reviewing the proposal and had a few questions on usage of the new params. 1) When using plaintext keys, is the "attributes" param unused and should/could it be set to NULL? 2) If using key store (i.e. opaque), is the key ID the only attribute field which needs to be set? My assumption is attributes would be populated from the key store using the key ID? 3) If using key store, are the "key_buffer" and "key_buffer_size" params typically unused (i.e. can be set to null and zero respectively)? I do the proposal says the buffer content is up to the driver. Are there any usage cases in mind? 4) For drivers that support both opaque and transparent operation, which param would be used to determine the mode? (I had assumed key ID = 0 would be transparent, and non-zero is opaque) I'm unclear how persistent_state for opaque driver's is used. Could you elaborate on how it's used by the driver and core and why it isn't needed for transparent drivers? Key management with opaque drivers Transparent drivers may provide the following key management functions: Should this be "Opaque"? Regards, Brian Quach SimpleLink MCU Texas Instruments Inc. 12500 TI Blvd, MS F-4000 Dallas, TX 75243 214-479-4076

5 years, 2 months

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Re: [mbed-tls] mbedtls_x509write_crt_set_subject_name, mbedtls_x509_dn_gets fail to handle UTF8 multibyte properly

by Martin Man

> On 11 Jun 2020, at 12:09, Gilles Peskine via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> wrote: > > On 11/06/2020 11:24, Martin Man via mbed-tls wrote: >> >> I think this is a bug and the dn_gets should simply leave the UTF-8 >> multibyte untouched when parsing it out from a field tagged with ASN.1 >> tag 12 (utf-8). > > We are not going to do Unicode normalization in Mbed TLS: that would be > far too complex for a library that runs on systems with ~1e5 bytes > available for code. So Unicode strings would only be processed correctly > if the application passes normalized strings and CAs only generate > certificates with normalized strings. But that would be an improvement > on converting non-ASCII characters to '?'. Definitely agree that normalization is not needed. I think this problem could be split into two parts: 1) When a const char* is passed into mbedtls_x509write_crt_set_subject_name, the mbedtls will currently encode it into ASN tag 12 UTF8. Not sure what validation is done. But it could perhaps do at least a basic validation of what the C string passed in is to avoid generating a cert with crippled DN. Alternatively you can simply trust the developer to pass in correct UTF8 and document this. This is a API design decision of what input is allowed to be passed into the method and what validation is done on this. 2) When the mbedtls_x509_dn_gets extracts a C string from the ASN.1 tagged as 12, it could validate that it is indeed valid UTF-8, or just leave it as is and push it out. Again, this is about what we expect the library to do. I’m not an expert on whether this can in any way be used to trick MBEDLTS to do bad things when sending in a malformed certificate, say a one where DN is encoded as UTF-8 but contains illegal UTF-8 in the payload. thanks for listening, Martin

5 years, 2 months

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Re: [mbed-tls] mbedtls_x509write_crt_set_subject_name, mbedtls_x509_dn_gets fail to handle UTF8 multibyte properly

by Gilles Peskine

On 11/06/2020 11:24, Martin Man via mbed-tls wrote: > The code in mbedtls_x509_dn_gets fails to properly handle the UTF-8 > multibyte sequence 0xe2 0x80 0x99 and turns it into 0xe2 0x80 0x3f. > > There is a fix floating around development branch mentioned > here https://github.com/ARMmbed/mbedtls/pull/3326/files which > essentially replaces all control chars with question marks. > > I think this is a bug and the dn_gets should simply leave the UTF-8 > multibyte untouched when parsing it out from a field tagged with ASN.1 > tag 12 (utf-8). That code is from an earlier era (mid 2000s, I think) when most systems used an 8-bit encoding, but non-8-bit-clean systems were still common. A '\x80' in text might be transformed to '\x00' with disastrous consequences. But over a decade later, I don't think non-8-bit-clean systems are a concern anymore. Leaving all non-ASCII characters alone sounds reasonable to me. We are not going to do Unicode normalization in Mbed TLS: that would be far too complex for a library that runs on systems with ~1e5 bytes available for code. So Unicode strings would only be processed correctly if the application passes normalized strings and CAs only generate certificates with normalized strings. But that would be an improvement on converting non-ASCII characters to '?'. -- Gilles Peskine Mbed TLS developer

5 years, 2 months

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mbedtls_x509write_crt_set_subject_name, mbedtls_x509_dn_gets fail to handle UTF8 multibyte properly

by Martin Man

Hi guys, I’m new to the list and bringing the discussion over here from https://github.com/ARMmbed/mbedtls/issues/3413 <https://github.com/ARMmbed/mbedtls/issues/3413>. I’m creating a certificate using mbedtls and setting it’s issuer and and subject using the mbedtls_x509write_crt_set_subject_name, and mbedtls_x509write_crt_set_issuer_name. The name passed in is in UTF8 and contains a sequence 0xe2 0x80 0x99 (apostrophe) in the CN string. If I debugged this correctly, the underlying sequence of bytes is correctly encoded in ASN.1 and tagged as 12 (UTF-8). When I later parse the cert and try to extract its subject back using mbedtls_x509_dn_gets from crt.subject and crt.issuer the UTF-8 gets corrupted. The code in mbedtls_x509_dn_gets fails to properly handle the UTF-8 multibyte sequence 0xe2 0x80 0x99 and turns it into 0xe2 0x80 0x3f. There is a fix floating around development branch mentioned here https://github.com/ARMmbed/mbedtls/pull/3326/files <https://github.com/ARMmbed/mbedtls/pull/3326/files> which essentially replaces all control chars with question marks. I think this is a bug and the dn_gets should simply leave the UTF-8 multibyte untouched when parsing it out from a field tagged with ASN.1 tag 12 (utf-8). What’s your opinion? Martin

5 years, 2 months

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ERROR: mbedtls_ssl_handshake returned -0x50 (with AWS IOT SDK )

by Srinivasa Rao Ragolu

Hi All, I recently started working on mbedtls for AWS IoT SDK based applications. Issue: I am planning to run AWS IoT SDK sample applications on my memory constrained (6MB RAM) embedded hardware Usage: AWS IOT SDK(3.0.1 release version) and mbedtls (2.16.5) Note: This filesystem is Read-Only file system. I have tried on Ubuntu 18.04 setup first to make things clear. It was not working with "AmazonRootCA1.pem" and working perfectly fine with cross-signed "G2-RootCA1.pem". Ref: https://docs.aws.amazon.com/iot/latest/developerguide/iot-embedded-c-sdk.ht… So I have cross-compiled for my target board using ARM toolchain and copied the binary and certificates. I have downloaded device certificate, private key and RootCA from AWS IOT Core to my device. Nothing on my device except copying the above 3 files. On my Embedded platform, whenever run my application, mbedtls is throwing the error "mbedtls_ssl_handshake returned -0x50" So I have enabled the debug in mbedtls library and ran below command to dig into the problem. $ ./ssl_client2 server_name=a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com<http://a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com/> serv er_port=443 ca_file=/certs/G2-RootCA1.pem crt_file=/certs/4960bd2f6b-certificate .pem.crt key_file=/certs/4960bd2f6b-private.pem.key Output: $ ./ssl_client2 server_name=a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com<http://a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com/> serv er_port=443 ca_file=/certs/G2-RootCA1.pem crt_file=/certs/4960bd2f6b-certificate .pem.crt key_file=/certs/4960bd2f6b-private.pem.key . Seeding the random number generator... ok . Loading the CA root certificate ... ok (0 skipped) . Loading the client cert. and key... ok . Connecting to tcp/a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com/443.<http://a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com/443.>.. ok . Setting up the SSL/TLS structure...ssl_tls.c:0081: |3| set_timer to 0 ms ok . Performing the SSL/TLS handshake...ssl_tls.c:8084: |2| => handshake ssl_cli.c:3510: |2| client state: 0 ssl_tls.c:2755: |2| => flush output ssl_tls.c:2767: |2| <= flush output ssl_cli.c:3510: |2| client state: 1 ssl_tls.c:2755: |2| => flush output ssl_tls.c:2767: |2| <= flush output ssl_cli.c:0774: |2| => write client hello ssl_cli.c:0811: |3| client hello, max version: [3:3] ssl_cli.c:0703: |3| client hello, current time: 1540981791 ssl_cli.c:0821: |3| dumping 'client hello, random bytes' (32 bytes) ssl_cli.c:0821: |3| 0000: 5b d9 84 1f 2f 33 35 54 ea 0b 5d e1 dc 42 0c 99 [.../35T..]..B.. ssl_cli.c:0821: |3| 0010: d4 a1 25 72 6f 0f cf 8e 56 0d ab f5 10 e4 47 46 ..%ro...V.....GF ssl_cli.c:0874: |3| client hello, session id len.: 0 ssl_cli.c:0875: |3| dumping 'client hello, session id' (0 bytes) ssl_cli.c:0921: |3| client hello, add ciphersuite: cca8 ssl_cli.c:0921: |3| client hello, add ciphersuite: cca9 ssl_cli.c:0921: |3| client hello, add ciphersuite: ccaa ssl_cli.c:0921: |3| client hello, add ciphersuite: c02c ssl_cli.c:0921: |3| client hello, add ciphersuite: c030 ssl_cli.c:0921: |3| client hello, add ciphersuite: 009f ssl_cli.c:0921: |3| client hello, add ciphersuite: c0ad ssl_cli.c:0921: |3| client hello, add ciphersuite: c09f ssl_cli.c:0921: |3| client hello, add ciphersuite: c024 ssl_cli.c:0921: |3| client hello, add ciphersuite: c028 ssl_cli.c:0921: |3| client hello, add ciphersuite: 006b ssl_cli.c:0921: |3| client hello, add ciphersuite: c00a ssl_cli.c:0921: |3| client hello, add ciphersuite: c014 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0039 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0af ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a3 ssl_cli.c:0921: |3| client hello, add ciphersuite: c087 ssl_cli.c:0921: |3| client hello, add ciphersuite: c08b ssl_cli.c:0921: |3| client hello, add ciphersuite: c07d ssl_cli.c:0921: |3| client hello, add ciphersuite: c073 ssl_cli.c:0921: |3| client hello, add ciphersuite: c077 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00c4 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0088 ssl_cli.c:0921: |3| client hello, add ciphersuite: c02b ssl_cli.c:0921: |3| client hello, add ciphersuite: c02f ssl_cli.c:0921: |3| client hello, add ciphersuite: 009e ssl_cli.c:0921: |3| client hello, add ciphersuite: c0ac ssl_cli.c:0921: |3| client hello, add ciphersuite: c09e ssl_cli.c:0921: |3| client hello, add ciphersuite: c023 ssl_cli.c:0921: |3| client hello, add ciphersuite: c027 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0067 ssl_cli.c:0921: |3| client hello, add ciphersuite: c009 ssl_cli.c:0921: |3| client hello, add ciphersuite: c013 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0033 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0ae ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a2 ssl_cli.c:0921: |3| client hello, add ciphersuite: c086 ssl_cli.c:0921: |3| client hello, add ciphersuite: c08a ssl_cli.c:0921: |3| client hello, add ciphersuite: c07c ssl_cli.c:0921: |3| client hello, add ciphersuite: c072 ssl_cli.c:0921: |3| client hello, add ciphersuite: c076 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00be ssl_cli.c:0921: |3| client hello, add ciphersuite: 0045 ssl_cli.c:0921: |3| client hello, add ciphersuite: ccac ssl_cli.c:0921: |3| client hello, add ciphersuite: ccad ssl_cli.c:0921: |3| client hello, add ciphersuite: 00ab ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a7 ssl_cli.c:0921: |3| client hello, add ciphersuite: c038 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00b3 ssl_cli.c:0921: |3| client hello, add ciphersuite: c036 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0091 ssl_cli.c:0921: |3| client hello, add ciphersuite: c091 ssl_cli.c:0921: |3| client hello, add ciphersuite: c09b ssl_cli.c:0921: |3| client hello, add ciphersuite: c097 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0ab ssl_cli.c:0921: |3| client hello, add ciphersuite: 00aa ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a6 ssl_cli.c:0921: |3| client hello, add ciphersuite: c037 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00b2 ssl_cli.c:0921: |3| client hello, add ciphersuite: c035 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0090 ssl_cli.c:0921: |3| client hello, add ciphersuite: c090 ssl_cli.c:0921: |3| client hello, add ciphersuite: c096 ssl_cli.c:0921: |3| client hello, add ciphersuite: c09a ssl_cli.c:0921: |3| client hello, add ciphersuite: c0aa ssl_cli.c:0921: |3| client hello, add ciphersuite: 009d ssl_cli.c:0921: |3| client hello, add ciphersuite: c09d ssl_cli.c:0921: |3| client hello, add ciphersuite: 003d ssl_cli.c:0921: |3| client hello, add ciphersuite: 0035 ssl_cli.c:0921: |3| client hello, add ciphersuite: c032 ssl_cli.c:0921: |3| client hello, add ciphersuite: c02a ssl_cli.c:0921: |3| client hello, add ciphersuite: c00f ssl_cli.c:0921: |3| client hello, add ciphersuite: c02e ssl_cli.c:0921: |3| client hello, add ciphersuite: c026 ssl_cli.c:0921: |3| client hello, add ciphersuite: c005 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a1 ssl_cli.c:0921: |3| client hello, add ciphersuite: c07b ssl_cli.c:0921: |3| client hello, add ciphersuite: 00c0 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0084 ssl_cli.c:0921: |3| client hello, add ciphersuite: c08d ssl_cli.c:0921: |3| client hello, add ciphersuite: c079 ssl_cli.c:0921: |3| client hello, add ciphersuite: c089 ssl_cli.c:0921: |3| client hello, add ciphersuite: c075 ssl_cli.c:0921: |3| client hello, add ciphersuite: 009c ssl_cli.c:0921: |3| client hello, add ciphersuite: c09c ssl_cli.c:0921: |3| client hello, add ciphersuite: 003c ssl_cli.c:0921: |3| client hello, add ciphersuite: 002f ssl_cli.c:0921: |3| client hello, add ciphersuite: c031 ssl_cli.c:0921: |3| client hello, add ciphersuite: c029 ssl_cli.c:0921: |3| client hello, add ciphersuite: c00e ssl_cli.c:0921: |3| client hello, add ciphersuite: c02d ssl_cli.c:0921: |3| client hello, add ciphersuite: c025 ssl_cli.c:0921: |3| client hello, add ciphersuite: c004 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a0 ssl_cli.c:0921: |3| client hello, add ciphersuite: c07a ssl_cli.c:0921: |3| client hello, add ciphersuite: 00ba ssl_cli.c:0921: |3| client hello, add ciphersuite: 0041 ssl_cli.c:0921: |3| client hello, add ciphersuite: c08c ssl_cli.c:0921: |3| client hello, add ciphersuite: c078 ssl_cli.c:0921: |3| client hello, add ciphersuite: c088 ssl_cli.c:0921: |3| client hello, add ciphersuite: c074 ssl_cli.c:0921: |3| client hello, add ciphersuite: ccae ssl_cli.c:0921: |3| client hello, add ciphersuite: 00ad ssl_cli.c:0921: |3| client hello, add ciphersuite: 00b7 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0095 ssl_cli.c:0921: |3| client hello, add ciphersuite: c093 ssl_cli.c:0921: |3| client hello, add ciphersuite: c099 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00ac ssl_cli.c:0921: |3| client hello, add ciphersuite: 00b6 ssl_cli.c:0921: |3| client hello, add ciphersuite: 0094 ssl_cli.c:0921: |3| client hello, add ciphersuite: c092 ssl_cli.c:0921: |3| client hello, add ciphersuite: c098 ssl_cli.c:0921: |3| client hello, add ciphersuite: ccab ssl_cli.c:0921: |3| client hello, add ciphersuite: 00a9 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a5 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00af ssl_cli.c:0921: |3| client hello, add ciphersuite: 008d ssl_cli.c:0921: |3| client hello, add ciphersuite: c08f ssl_cli.c:0921: |3| client hello, add ciphersuite: c095 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a9 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00a8 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a4 ssl_cli.c:0921: |3| client hello, add ciphersuite: 00ae ssl_cli.c:0921: |3| client hello, add ciphersuite: 008c ssl_cli.c:0921: |3| client hello, add ciphersuite: c08e ssl_cli.c:0921: |3| client hello, add ciphersuite: c094 ssl_cli.c:0921: |3| client hello, add ciphersuite: c0a8 ssl_cli.c:0934: |3| client hello, got 127 ciphersuites (excluding SCSVs) ssl_cli.c:0943: |3| adding EMPTY_RENEGOTIATION_INFO_SCSV ssl_cli.c:0992: |3| client hello, compress len.: 1 ssl_cli.c:0993: |3| client hello, compress alg.: 0 ssl_cli.c:0068: |3| client hello, adding server name extension: a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com<http://a2g7twmqo7hg82-ats.iot.ap-south-1.amazonaws.com/> ssl_cli.c:0186: |3| client hello, adding signature_algorithms extension ssl_cli.c:0271: |3| client hello, adding supported_elliptic_curves extension ssl_cli.c:0336: |3| client hello, adding supported_point_formats extension ssl_cli.c:0517: |3| client hello, adding encrypt_then_mac extension ssl_cli.c:0551: |3| client hello, adding extended_master_secret extension ssl_cli.c:0585: |3| client hello, adding session ticket extension ssl_cli.c:1070: |3| client hello, total extension length: 128 ssl_tls.c:3184: |2| => write handshake message ssl_tls.c:3343: |2| => write record ssl_tls.c:3420: |3| output record: msgtype = 22, version = [3:1], msglen = 429 ssl_tls.c:3425: |4| dumping 'output record sent to network' (434 bytes) ssl_tls.c:3425: |4| 0000: 16 03 01 01 ad 01 00 01 a9 03 03 5b d9 84 1f 2f ...........[.../ ssl_tls.c:3425: |4| 0010: 33 35 54 ea 0b 5d e1 dc 42 0c 99 d4 a1 25 72 6f 35T..]..B....%ro ssl_tls.c:3425: |4| 0020: 0f cf 8e 56 0d ab f5 10 e4 47 46 00 01 00 cc a8 ...V.....GF..... ssl_tls.c:3425: |4| 0030: cc a9 cc aa c0 2c c0 30 00 9f c0 ad c0 9f c0 24 .....,.0.......$ ssl_tls.c:3425: |4| 0040: c0 28 00 6b c0 0a c0 14 00 39 c0 af c0 a3 c0 87 .(.k.....9...... ssl_tls.c:3425: |4| 0050: c0 8b c0 7d c0 73 c0 77 00 c4 00 88 c0 2b c0 2f ...}.s.w.....+./ ssl_tls.c:3425: |4| 0060: 00 9e c0 ac c0 9e c0 23 c0 27 00 67 c0 09 c0 13 .......#.'.g.... ssl_tls.c:3425: |4| 0070: 00 33 c0 ae c0 a2 c0 86 c0 8a c0 7c c0 72 c0 76 .3.........|.r.v ssl_tls.c:3425: |4| 0080: 00 be 00 45 cc ac cc ad 00 ab c0 a7 c0 38 00 b3 ...E.........8.. ssl_tls.c:3425: |4| 0090: c0 36 00 91 c0 91 c0 9b c0 97 c0 ab 00 aa c0 a6 .6.............. ssl_tls.c:3425: |4| 00a0: c0 37 00 b2 c0 35 00 90 c0 90 c0 96 c0 9a c0 aa .7...5.......... ssl_tls.c:3425: |4| 00b0: 00 9d c0 9d 00 3d 00 35 c0 32 c0 2a c0 0f c0 2e .....=.5.2.*.... ssl_tls.c:3425: |4| 00c0: c0 26 c0 05 c0 a1 c0 7b 00 c0 00 84 c0 8d c0 79 .&.....{.......y ssl_tls.c:3425: |4| 00d0: c0 89 c0 75 00 9c c0 9c 00 3c 00 2f c0 31 c0 29 ...u.....<./.1.) ssl_tls.c:3425: |4| 00e0: c0 0e c0 2d c0 25 c0 04 c0 a0 c0 7a 00 ba 00 41 ...-.%.....z...A ssl_tls.c:3425: |4| 00f0: c0 8c c0 78 c0 88 c0 74 cc ae 00 ad 00 b7 00 95 ...x...t........ ssl_tls.c:3425: |4| 0100: c0 93 c0 99 00 ac 00 b6 00 94 c0 92 c0 98 cc ab ................ ssl_tls.c:3425: |4| 0110: 00 a9 c0 a5 00 af 00 8d c0 8f c0 95 c0 a9 00 a8 ................ ssl_tls.c:3425: |4| 0120: c0 a4 00 ae 00 8c c0 8e c0 94 c0 a8 00 ff 01 00 ................ ssl_tls.c:3425: |4| 0130: 00 80 00 00 00 34 00 32 00 00 2f 61 32 67 37 74 .....4.2../a2g7t ssl_tls.c:3425: |4| 0140: 77 6d 71 6f 37 68 67 38 32 2d 61 74 73 2e 69 6f wmqo7hg82-ats.io<http://wmqo7hg82-ats.io/> ssl_tls.c:3425: |4| 0150: 74 2e 61 70 2d 73 6f 75 74 68 2d 31 2e 61 6d 61 t.ap-south-1.ama ssl_tls.c:3425: |4| 0160: 7a 6f 6e 61 77 73 2e 63 6f 6d 00 0d 00 16 00 14 zonaws.com...... ssl_tls.c:3425: |4| 0170: 06 03 06 01 05 03 05 01 04 03 04 01 03 03 03 01 ................ ssl_tls.c:3425: |4| 0180: 02 03 02 01 00 0a 00 18 00 16 00 19 00 1c 00 18 ................ ssl_tls.c:3425: |4| 0190: 00 1b 00 17 00 16 00 1a 00 15 00 14 00 13 00 12 ................ ssl_tls.c:3425: |4| 01a0: 00 0b 00 02 01 00 00 16 00 00 00 17 00 00 00 23 ...............# ssl_tls.c:3425: |4| 01b0: 00 00 .. ssl_tls.c:2755: |2| => flush output ssl_tls.c:2773: |2| message length: 434, out_left: 434 ssl_tls.c:2779: |2| ssl->f_send() returned 434 (-0xfffffe4e) ssl_tls.c:2807: |2| <= flush output ssl_tls.c:3476: |2| <= write record ssl_tls.c:3320: |2| <= write handshake message ssl_cli.c:1106: |2| <= write client hello ssl_cli.c:3510: |2| client state: 2 ssl_tls.c:2755: |2| => flush output ssl_tls.c:2767: |2| <= flush output ssl_cli.c:1499: |2| => parse server hello ssl_tls.c:4311: |2| => read record ssl_tls.c:2536: |2| => fetch input ssl_tls.c:2696: |2| in_left: 0, nb_want: 5 ssl_tls.c:2720: |2| in_left: 0, nb_want: 5 ssl_tls.c:2722: |2| ssl->f_recv(_timeout)() returned -80 (-0x0050) ssl_tls.c:4973: |1| mbedtls_ssl_fetch_input() returned -80 (-0x0050) ssl_tls.c:4344: |1| ssl_get_next_record() returned -80 (-0x0050) ssl_cli.c:1506: |1| mbedtls_ssl_read_record() returned -80 (-0x0050) ssl_tls.c:8094: |2| <= handshake failed ! mbedtls_ssl_handshake returned -0x50 Last error was: -0x50 - NET - Connection was reset by peer ssl_tls.c:8934: |2| => free ssl_tls.c:8999: |2| <= free I request you to help me in resolving this issue. Regards, Srinivas. [cid:ef4e58a5-df1a-47f0-90b9-c467a93244c2]

5 years, 2 months

1
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Re: [mbed-tls] support mbedTLS no entropy source

by Dan Handley

Hi Palomo All the documentation we have to share is already available, either in the upstream codebase, the wiki (https://developer.trustedfirmware.org/w/mbed-tls/) or the legacy website (https://tls.mbed.org/). Some of the info on the latter is out of date. The core development team at Arm do not offer training. Arm has a Partner Enablement Group that does this kind of thing but I don't think they offer Mbed TLS specific training currently. I've asked them if they would consider this in future but I guess that's not going to help you in the short term. Good luck with your learning and we'll try to answer any specific questions you have. Regards Dan. From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> On Behalf Of Jesus Gualberto Palomo Garcia via mbed-tls Sent: 08 June 2020 04:46 To: Gilles Peskine <Gilles.Peskine(a)arm.com> Cc: mbed-tls(a)lists.trustedfirmware.org Subject: Re: [mbed-tls] support mbedTLS no entropy source Hi Gilles. Thanks for follow my questions and attend it, regarding trainings, I want to understand how the encryption works, how the algorithms works inside the library, I can read the code and google the concepts but I want to accelerate the knowledge transfer, maybe for implement some optimization, I don't if that is possible, at the moment my PoC using uClinux works perfectly and the TLS 1.2 ir running over 80Mhz, so that is pretty awesome, but I want to learn more about encryption, maybe if you can share me some literature regarding this point? Thank you very much and regards from Mexico! On Tue, Jun 2, 2020 at 6:21 PM Gilles Peskine <gilles.peskine(a)arm.com<mailto:gilles.peskine@arm.com>> wrote: Hi Palomo, I don't think there's any other way at the moment. The patch in my email is one possible solution, but I'm not sure if it's right, because not all platforms with a Linux kernel have /dev/urandom. I think the best solution would be to make the existence of /dev/urandom a platform configuration option. But platform options are a little messy already, between the MBEDTLS_HAVE_xxx options, the MBEDTLS_PLATFORM_STD_xxx options, the MBEDTLS_PLATFORM_xxx_MACRO options, the MBEDTLS_PLATFORM_xxx_ALT options. And this new option wouldn't behave like any of the existing ones since it should have three settings: guess (the default, identical to the current behavior of observing preprocessor symbols like __unix__), off and on. We should figure out what to do about platform options in 3.0 before making this even more complex. me.todo.add("collect my thoughts on simplifying platform customization and post them to the list") Regarding trainings, my team doesn't normally do that, but there are other teams in Arm that do. What topic are you interested in? -- Gilles Peskine Mbed TLS developer On 31/05/2020 20:06, Jesus Gualberto Palomo Garcia wrote: > Hello Gilles thanks for your support, yes finally I could compile the > library in the architecture that I used, I forced the compilation to > entry in the "if _unix_" conditional compilation, but I assume that > exist another way to do this. Do you have a example for enable that > conditional compilation flags? > > regarding to my dev/urandom, yes my platform has this feature, the > library runs very well, but I just have the point related to "force" > the compilation because the library doesn't recognize the unix > architecture. > > Thanks and we keep in touch! > > Regards from Mexico! > > BTW If I want to professional training, Do you offered this service? > > On Mon, May 25, 2020 at 11:07 AM Gilles Peskine via mbed-tls > <mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>>> wrote: > > Hi Palomo, > > You seem to be compiling for a system with a Linux kernel, but > with only > a partial Unix userland. The “Unix” code in the entropy_poll module > might work on your system, but it is only enabled if __unix__ or > __unix > (or a few others) is defined. > > Can you please try the attached patch? Does your runtime environment > have /dev/urandom ? > > Regarding the knowledge base article, you need to remove the "." > character at the end of the URL: > https://tls.mbed.org/kb/how-to/add-a-random-generator-- > > Gilles Peskine > Mbed TLS developer > > On 19/05/2020 21:43, Jesus Gualberto Palomo Garcia via mbed-tls wrote: > > Hello Hanno, Thanks for your thanks for you quickly replay. > > > > I have an error compilation, I'm using nios2-linux-uclibc for my > cross > > compilation and uclinux architecture, > > the linux kernel is 2.60 but I have this error when I try to compile > > the library, I want to use the library as a simple client using > TLS1.2 > > > > $ make static > > CC aes.c > > CC aesni.c > > CC arc4.c > > CC aria.c > > CC asn1parse.c > > CC asn1write.c > > CC base64.c > > CC bignum.c > > CC blowfish.c > > CC camellia.c > > CC ccm.c > > CC chacha20.c > > CC chachapoly.c > > CC cipher.c > > CC cipher_wrap.c > > CC cmac.c > > CC ctr_drbg.c > > CC des.c > > CC dhm.c > > CC ecdh.c > > CC ecdsa.c > > CC ecjpake.c > > CC ecp.c > > CC ecp_curves.c > > CC entropy.c > > CC entropy_poll.c > > entropy_poll.c:56:2: #error "Platform entropy sources only work on > > Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" > > Makefile:285: recipe for target 'entropy_poll.o' failed > > make: *** [entropy_poll.o] Error 1 > > > > BTW the article is not > > found https://tls.mbed.org/kb/how-to/add-a-random-generator. > > <https://tls.mbed.org/kb/how-to/add-a-random-generator.> > > > > Many thanks!! > > > > > > On Tue, May 19, 2020 at 9:01 AM Hanno Becker > <Hanno.Becker(a)arm.com<mailto:Hanno.Becker@arm.com> <mailto:Hanno.Becker@arm.com<mailto:Hanno.Becker@arm.com>> > > <mailto:Hanno.Becker@arm.com<mailto:Hanno.Becker@arm.com> <mailto:Hanno.Becker@arm.com<mailto:Hanno.Becker@arm.com>>>> wrote: > > > > Hi Palomo, > > > > Please take a look at the recent > > > thread https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000069.html > > which should give you a better understanding of how Mbed TLS > > manages and uses entropy from the underlying system. > > > > Regards, > > Hanno > > > ------------------------------------------------------------------------ > > *From:* mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org<mailto:mbed-tls-bounces@lists.trustedfirmware.org> > <mailto:mbed-tls-bounces@lists.trustedfirmware.org<mailto:mbed-tls-bounces@lists.trustedfirmware.org>> > > <mailto:mbed-tls-bounces@lists.trustedfirmware.org<mailto:mbed-tls-bounces@lists.trustedfirmware.org> > <mailto:mbed-tls-bounces@lists.trustedfirmware.org<mailto:mbed-tls-bounces@lists.trustedfirmware.org>>>> on behalf of > > Jesus Gualberto Palomo Garcia via mbed-tls > > <mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>> > > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>>>> > > *Sent:* Tuesday, May 19, 2020 2:56 PM > > *To:* mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>> > > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>>> > > <mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>> > > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>>>> > > *Subject:* [mbed-tls] support mbedTLS no entropy source > > > > Hi all! > > > > I'm Palomo and I've been working with your library a few weeks > > ago, I'm using Linux kernel 2.60 but my embedded system has a > > limit entropy source, i now that this is a critical point, > but How > > can I use your library if I want to use a other entropy source? > > > > Thanks and waiting for you! > > > > -- > > *¡Saludos! Best wishes!* > > * > > * > > * > > /*Jesus** Palomo*/ > > > > México, D.F. > > > > * > > > > > > > > -- > > *¡Saludos! Best wishes!* > > * > > * > > * > > /*Jesus** Palomo*/ > > > > México, D.F. > > > > * > > > > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> > <mailto:mbed-tls@lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org>> > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls > > > > -- > *¡Saludos! Best wishes!* > * > * > * > /*Jesus** Palomo*/ > > México, D.F. > > * -- ¡Saludos! Best wishes! Jesus Palomo México, D.F.

5 years, 2 months

1
0
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Re: [mbed-tls] support mbedTLS no entropy source

by Jesus Gualberto Palomo Garcia

Hello Gilles thanks for your support, yes finally I could compile the library in the architecture that I used, I forced the compilation to entry in the "if _unix_" conditional compilation, but I assume that exist another way to do this. Do you have a example for enable that conditional compilation flags? regarding to my dev/urandom, yes my platform has this feature, the library runs very well, but I just have the point related to "force" the compilation because the library doesn't recognize the unix architecture. Thanks and we keep in touch! Regards from Mexico! BTW If I want to professional training, Do you offered this service? On Mon, May 25, 2020 at 11:07 AM Gilles Peskine via mbed-tls < mbed-tls(a)lists.trustedfirmware.org> wrote: > Hi Palomo, > > You seem to be compiling for a system with a Linux kernel, but with only > a partial Unix userland. The “Unix” code in the entropy_poll module > might work on your system, but it is only enabled if __unix__ or __unix > (or a few others) is defined. > > Can you please try the attached patch? Does your runtime environment > have /dev/urandom ? > > Regarding the knowledge base article, you need to remove the "." > character at the end of the URL: > https://tls.mbed.org/kb/how-to/add-a-random-generator-- > > Gilles Peskine > Mbed TLS developer > > On 19/05/2020 21:43, Jesus Gualberto Palomo Garcia via mbed-tls wrote: > > Hello Hanno, Thanks for your thanks for you quickly replay. > > > > I have an error compilation, I'm using nios2-linux-uclibc for my cross > > compilation and uclinux architecture, > > the linux kernel is 2.60 but I have this error when I try to compile > > the library, I want to use the library as a simple client using TLS1.2 > > > > $ make static > > CC aes.c > > CC aesni.c > > CC arc4.c > > CC aria.c > > CC asn1parse.c > > CC asn1write.c > > CC base64.c > > CC bignum.c > > CC blowfish.c > > CC camellia.c > > CC ccm.c > > CC chacha20.c > > CC chachapoly.c > > CC cipher.c > > CC cipher_wrap.c > > CC cmac.c > > CC ctr_drbg.c > > CC des.c > > CC dhm.c > > CC ecdh.c > > CC ecdsa.c > > CC ecjpake.c > > CC ecp.c > > CC ecp_curves.c > > CC entropy.c > > CC entropy_poll.c > > entropy_poll.c:56:2: #error "Platform entropy sources only work on > > Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" > > Makefile:285: recipe for target 'entropy_poll.o' failed > > make: *** [entropy_poll.o] Error 1 > > > > BTW the article is not > > found https://tls.mbed.org/kb/how-to/add-a-random-generator. > > <https://tls.mbed.org/kb/how-to/add-a-random-generator.> > > > > Many thanks!! > > > > > > On Tue, May 19, 2020 at 9:01 AM Hanno Becker <Hanno.Becker(a)arm.com > > <mailto:Hanno.Becker@arm.com>> wrote: > > > > Hi Palomo, > > > > Please take a look at the recent > > thread > https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000069.html > > > which should give you a better understanding of how Mbed TLS > > manages and uses entropy from the underlying system. > > > > Regards, > > Hanno > > > ------------------------------------------------------------------------ > > *From:* mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org > > <mailto:mbed-tls-bounces@lists.trustedfirmware.org>> on behalf of > > Jesus Gualberto Palomo Garcia via mbed-tls > > <mbed-tls(a)lists.trustedfirmware.org > > <mailto:mbed-tls@lists.trustedfirmware.org>> > > *Sent:* Tuesday, May 19, 2020 2:56 PM > > *To:* mbed-tls(a)lists.trustedfirmware.org > > <mailto:mbed-tls@lists.trustedfirmware.org> > > <mbed-tls(a)lists.trustedfirmware.org > > <mailto:mbed-tls@lists.trustedfirmware.org>> > > *Subject:* [mbed-tls] support mbedTLS no entropy source > > > > Hi all! > > > > I'm Palomo and I've been working with your library a few weeks > > ago, I'm using Linux kernel 2.60 but my embedded system has a > > limit entropy source, i now that this is a critical point, but How > > can I use your library if I want to use a other entropy source? > > > > Thanks and waiting for you! > > > > -- > > *¡Saludos! Best wishes!* > > * > > * > > * > > /*Jesus** Palomo*/ > > > > México, D.F. > > > > * > > > > > > > > -- > > *¡Saludos! Best wishes!* > > * > > * > > * > > /*Jesus** Palomo*/ > > > > México, D.F. > > > > * > > > > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls > -- *¡Saludos! Best wishes!* *Jesus PalomoMéxico, D.F.*

5 years, 2 months

2
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Feedback sought on a new PSA Crypto driver interface

by Gilles Peskine

Hello, Arm is seeking early feedback on a proposed interface for cryptographic drivers that can be plugged into an implementation of the PSA Cryptography API. A copy of the current specification is attached. You can find the current draft of the specification of this interface at https://github.com/gilles-peskine-arm/mbedtls/blob/psa-unified-driver-proto… Please note that this is work in progress. The document is not complete yet. At this stage, it is intended to offer a general overview of the design, not as an implementable specification. Our intention is to continue refining this design, however we may change it based on the feedback that we will receive and there is even a small chance that we will abandon it. The primary intent of this specification is to allow manufacturers of cryptographic hardware to distribute drivers that can be added to a pure-software, portable implementation of the PSA Cryptography API such as Mbed TLS. The interface was designed to support three types of hardware: * Cryptographic accelerators that operate on a key which is provided in cleartext at the beginning of the operation. This type of driver can also be used to plug in software engines. * Protected environments that operate on a wrapped key which is stored outside the protected environment. * Protected environments that have internal key storage and operate on keys designated by an identifier. Concretely, a driver manufacturer would distribute: * A JSON file specifying the driver's capabilities. * C headers declaring the types and functions provided by the driver. * The implementation of the functions provided by the driver, either in the form of C source code or in the form of compiled code. Then when an application uses a key: * If the key is in the memory or local storage of the PSA crypto subsystem and a driver is available for the requested cryptographic mechanism, the core (e.g. Mbed TLS) dispatches the cryptographic operation to the driver. * If the key is in local storage and no driver is available, the core performs the cryptographic operation itself. * If the key is in some other location (as specified by its lifetime), the core invokes the protected environment driver corresponding to that location. This proposal supersedes the previous drafts “PSA cryptographic accelerator interface” (psa_crypto_accel.h) and “PSA secure element driver interface” (crypto_se_driver.h). We intend to implement this specification in Mbed TLS in such a way that a platform distributor can combine drivers and distribute C source code, object files or a mixture of the two in their system development kit. In the long term, the accelerator interface defined here will replace the current MBEDTLS_xxx_ALT mechanism. Comments are welcome through the following venues: * Public email to the psa-crypto or mbed-tls mailing list at TrustedFirmware. * Public comments on GitHub on the pull request https://github.com/ARMmbed/mbedtls/pull/3313 . * Private email to <mbed-crypto(a)arm.com>. These emails will only be shared inside Arm. We may use your feedback to influence the design of PSA Crypto, but your identity and the specifics will be kept confidential. We do not have a specific deadline for feedback, however we intend to start implementing this interface in Mbed TLS in June 2020, so feedback received later will have a reduced chance of influencing the design if it would entail major changes. Best regards, -- Gilles Peskine Mbed TLS developer and PSA Cryptography architect

5 years, 3 months

1
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Re: [mbed-tls] support mbedTLS no entropy source

by Gilles Peskine

Hi Palomo, You seem to be compiling for a system with a Linux kernel, but with only a partial Unix userland. The “Unix” code in the entropy_poll module might work on your system, but it is only enabled if __unix__ or __unix (or a few others) is defined. Can you please try the attached patch? Does your runtime environment have /dev/urandom ? Regarding the knowledge base article, you need to remove the "." character at the end of the URL: https://tls.mbed.org/kb/how-to/add-a-random-generator-- Gilles Peskine Mbed TLS developer On 19/05/2020 21:43, Jesus Gualberto Palomo Garcia via mbed-tls wrote: > Hello Hanno, Thanks for your thanks for you quickly replay. > > I have an error compilation, I'm using nios2-linux-uclibc for my cross > compilation and uclinux architecture, > the linux kernel is 2.60 but I have this error when I try to compile > the library, I want to use the library as a simple client using TLS1.2 > > $ make static > CC aes.c > CC aesni.c > CC arc4.c > CC aria.c > CC asn1parse.c > CC asn1write.c > CC base64.c > CC bignum.c > CC blowfish.c > CC camellia.c > CC ccm.c > CC chacha20.c > CC chachapoly.c > CC cipher.c > CC cipher_wrap.c > CC cmac.c > CC ctr_drbg.c > CC des.c > CC dhm.c > CC ecdh.c > CC ecdsa.c > CC ecjpake.c > CC ecp.c > CC ecp_curves.c > CC entropy.c > CC entropy_poll.c > entropy_poll.c:56:2: #error "Platform entropy sources only work on > Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" > Makefile:285: recipe for target 'entropy_poll.o' failed > make: *** [entropy_poll.o] Error 1 > > BTW the article is not > found https://tls.mbed.org/kb/how-to/add-a-random-generator. > <https://tls.mbed.org/kb/how-to/add-a-random-generator.> > > Many thanks!! > > > On Tue, May 19, 2020 at 9:01 AM Hanno Becker <Hanno.Becker(a)arm.com > <mailto:Hanno.Becker@arm.com>> wrote: > > Hi Palomo, > > Please take a look at the recent > thread https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000069.html > which should give you a better understanding of how Mbed TLS > manages and uses entropy from the underlying system. > > Regards, > Hanno > ------------------------------------------------------------------------ > *From:* mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org > <mailto:mbed-tls-bounces@lists.trustedfirmware.org>> on behalf of > Jesus Gualberto Palomo Garcia via mbed-tls > <mbed-tls(a)lists.trustedfirmware.org > <mailto:mbed-tls@lists.trustedfirmware.org>> > *Sent:* Tuesday, May 19, 2020 2:56 PM > *To:* mbed-tls(a)lists.trustedfirmware.org > <mailto:mbed-tls@lists.trustedfirmware.org> > <mbed-tls(a)lists.trustedfirmware.org > <mailto:mbed-tls@lists.trustedfirmware.org>> > *Subject:* [mbed-tls] support mbedTLS no entropy source > > Hi all! > > I'm Palomo and I've been working with your library a few weeks > ago, I'm using Linux kernel 2.60 but my embedded system has a > limit entropy source, i now that this is a critical point, but How > can I use your library if I want to use a other entropy source? > > Thanks and waiting for you! > > -- > *¡Saludos! Best wishes!* > * > * > * > /*Jesus** Palomo*/ > > México, D.F. > > * > > > > -- > *¡Saludos! Best wishes!* > * > * > * > /*Jesus** Palomo*/ > > México, D.F. > > * >

5 years, 3 months

1
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Re: [mbed-tls] support mbedTLS no entropy source

by Hanno Becker

Hi Palomo, Please take a look at the recent thread https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000069.html which should give you a better understanding of how Mbed TLS manages and uses entropy from the underlying system. Regards, Hanno ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Jesus Gualberto Palomo Garcia via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: Tuesday, May 19, 2020 2:56 PM To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: [mbed-tls] support mbedTLS no entropy source Hi all! I'm Palomo and I've been working with your library a few weeks ago, I'm using Linux kernel 2.60 but my embedded system has a limit entropy source, i now that this is a critical point, but How can I use your library if I want to use a other entropy source? Thanks and waiting for you! -- ¡Saludos! Best wishes! Jesus Palomo México, D.F.

5 years, 3 months

2
1
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support mbedTLS no entropy source

by Jesus Gualberto Palomo Garcia

Hi all! I'm Palomo and I've been working with your library a few weeks ago, I'm using Linux kernel 2.60 but my embedded system has a limit entropy source, i now that this is a critical point, but How can I use your library if I want to use a other entropy source? Thanks and waiting for you! -- *¡Saludos! Best wishes!* *Jesus PalomoMéxico, D.F.*

5 years, 3 months

1
0
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Re: [mbed-tls] Psk tls with trustzone

by Gilles Peskine

Hello, If you enable the use PSA for cryptography in TLS (MBEDTLS_USE_PSA_CRYPTO) and configure the PSK with mbedtls_ssl_conf_psk_opaque(), the key derivation is done through the PSA API. You can then keep your key in the secure world. You'll need to have a PSA crypto implementation where the PSA crypto core is in the secure world and the frontend is in the application that performs the TLS handshake. PSA crypto is designed for this, but you or your TEE vendor will need to port the Mbed TLS code to your platform. -- Gilles Peskine Mbed TLS developer On 13/05/2020 11:10, mayuri janawad via mbed-tls wrote: > Hello, > > I am currently trying to establish pre shared key based tls handshake > using mbedtls. However, I want to store the pre shared key in the > trustzone and derive the session key inside the trustzone. Is it > possible using mbedtls? Can I provide alternate implementation for psk > based tls in mbedtls library? > > It would be really helpful if this could be answered as soon as > possible. Thank you in advance for your assistance. > > Regards, > Mayuri Janawad >

5 years, 3 months

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Psk tls with trustzone

by mayuri janawad

Hello, I am currently trying to establish pre shared key based tls handshake using mbedtls. However, I want to store the pre shared key in the trustzone and derive the session key inside the trustzone. Is it possible using mbedtls? Can I provide alternate implementation for psk based tls in mbedtls library? It would be really helpful if this could be answered as soon as possible. Thank you in advance for your assistance. Regards, Mayuri Janawad

5 years, 3 months

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Re: [mbed-tls] ECDH Computation on STM32 platform

by Manuel Pegourie-Gonnard

Hi Abhilash, > I am trying to do the ECDH shared secret computation using the mbedTLS > library. I am referring to multiple examples such as ecdh_curve25519.c > and ecdh_main.c. > Ok. You should probably know a few things about those examples: 1. They both perform what's known as "ephemeral ECDH" (or sometimes ECDHE). 2. They're both using the low-level part of our ECDH API. For ecdh_curve25519, that is because that curve is not supported by the higher-level API yet - for the other example, I don't know what the reason is. 3. Curve25519 is quite different from other curves regarding how public keys are represented. > In my case, in my application firmware, I already have a device _priv > key and I receive a server_public key; both generated using a curve > ECP_DP_SECP256R1 in the bootloader itself. So in the application > firmware, I would like to do generate a shared secret from here on and > preserve it for future use. > Ok, so you want to do what's known as "static ECDH". So the example ecdh_curve25519 is not a great example, due to points 1 and 3 above. Also, since the curve you're using supports it, you may want to use the higher-level part of our ECDH API (the functions that accept a context as an argument). > The following is the steps that I do: > > 1. Create a new client context, entropy context, ctr_drbg context variables. > 2. use mbedtls_"respective"_init() to initalize all the three variables > 3. Seed a random number using mbedtls_ctr_drbg_seed() function. > 4. load the P256 elliptic curve in client context using mbedtls_ecp_group_load() All this looks absolutely correct. > 5. Then use mbedtls_mpi_lset() to set Qp.Z =1 > 6. Then read the server pub key using mbedtls_mpi_read_binary(&ctx_cli.Qp.X, server_pub, 65); >From the 65 I assume that the server public key as encoded as an uncompressed point. Then you can read it with: mbedtls_ecp_point_read_binary(&ctx_cli.grp, &ctx_cli.Qp, server_pub, 65); (For Curve25519 mbedtls_ecp_point_read_binary() isn't implemented yet which is why the example does a direct call to an MPI function and accesses individual point coordinates, but Curve25519 and P-256 don't use the same coordinate systems.) > 7. Now the question is: Should I initialize the ctx_cli with my already generated device_priv key using > mbedtls_mpi_read_binary(&ctx_cli.d, device_priv_key, 50) ? That looks almost correct, except 50 does not look like a valid size for a private key for the curve you're using. > 8. Then I use mbedtls_ecdh_compute_shared(&ctx_cli.grp, &ctx_cli.z, &ctx_cli.Qp, &ctx_cli.d, mbedtls_ctr_drbg_random, &ctr_drbg); to compute the shared secret in z. > That's correct, but you could also call mbedtls_ecdh_calc_secret( &ctx_cli, &olen, buf, blen, mbedtls_ctr_drbg_random, &ctr_drbg ); which also serializes the secret to a buffer. > Questions: > 1. Do I need to generate a keypair for client context using > mbedtls_ecdh_gen_public(&ctx_cli.grp, &ctx_cli.d, &ctx_cli.Q, > mbedtls_ctr_drbg_random, &ctrDrbg)? And then set pvtkey as device priv > key and pub key as service pub key? > I'm not sure I understand the context of the question, so I'll distinguish two cases: - When provisioning the device, you need to generate a key pair for it, which can indeed be done as show. - Once the device is working, it doesn't need to generate new key pairs, just load the one that was provisioned as described below. > 2. I see that ctx_cli.Q has two components, Q.x and Q.y. How do I > extract these two values from a public key? Do I need to separately > initialize them? > I don't recommend you manipulate those directly, but use the `mbedtls_ecp_point_{read,write}_binary()` functions instead. > Please let me know if the flow is correct. In all the examples, they > generate a key pair and just update the public key part (Qp.X) of the > key. They do not touch the private key part (d) of the key. Please > confirm if I can upload my private key directly in my case. > Your flow looks correct, and the difference from the examples is that they're demonstrating ephemeral ECDH while it looks like you want to do static ECDH. > Also if my platform is a little endian, is there a recommended step > before using mbedtls_mpi_read_binary_le functions? Then endianness of your plaftorm should not matter, and you shouldn't need to use that function. Regards, Manuel.

5 years, 3 months

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Re: [mbed-tls] Edwards curve support (#3245): fixing mbedtls_ecp_get_type

by Manuel Pegourie-Gonnard

Hi Aurélien, > I have submitted PR#3245 in order to add Edwards curves support to Mbed > TLS, with the eventual goal to add support for the EdDSA algorithm. > There are still a few things to fix that require discussion. > Thank you very much for your contribution, and for opening this discussion! > Let's start the discussion with the first one. Adding a new curve type > requires to add a new entry to the mbedtls_ecp_curve_type enum. The > curve type used by a group is returned by the mbedtls_ecp_get_type > function. It currently uses the coordinates type of the base point to > determine the curve type. Montgomery curves are lacking the y > coordinate, and the Short Weierstrass curves use the three x, y and z > coordinates. > > The Edwards arithmetic implementation in this PR uses the projective > coordinates. As such it also uses the x, y and z coordinates and this > gives no way to differentiate a Short Weierstrass from an Edwards curve. > Indeed, the current implementation of `ecp_curve_type()` is a bit of a hack and needs changing now that you're adding Edwards curves. > I have currently implemented that by checking if the curves are the > Ed25519 or Ed448 ones using the group id [1]. I am not sure it's very > clean and it won't scale if more curves are added later. Another > alternative would be to add another entry to mbedtls_ecp_group to hold > the curve type. > > What do you think is the best option? Any other idea? Honestly I think both options are fine. In the medium term (in 3.0 or 3.x) I'd like to entirely rework the `ecp_group` structure, which currently potentially wastes memory by having multiple instances for the same curve around (for example, when verifying a chain of N certificates all signed with the same curve, we'll have N instances of the `ecp_group` structure for that curve in RAM, which is quite wasteful). So I think in the meantime we don't need to sweat it too much. I have a slight preference for the option you currently implemented (checking the group ID), for two reasons: 1. Lack of scaling is not an issue, as it's unlikely a large number of Edwards curves are going to be added soon (in particular, not before the rework of ecp_group), since these last few years the tendency seems to be to focus on a small number of trusted curves [1]. 2. Adding a new member to `mbedtls_ecp_group` would be an ABI break, and while we don't have a strict policy of ABI stability, it tends to cause pain to packagers if we change the ABI too often, so it's probably better to avoid it if we can. Thanks, Manuel. [1] For example, compare https://tools.ietf.org/html/rfc4492#section-5.1.1 to https://tools.ietf.org/html/rfc8422#section-5.1.1

5 years, 3 months

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Re: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code base

by Manuel Pegourie-Gonnard

Hi Simon, > I appreciate I'm coming very late to this discussion, but I want to make a > point and suggestion. > Well, I don't think we had reached a clear consensus yet, so it's not too late to explore more options! > These are very similar points to those Manuel was making to remove the feature > in the first place - however - short of investing the time in rewriting the > asymmetric functions, what we could do as a quick fix is to replace the > existing memory code with a block allocation scheme - which should be much > faster, speed up the asymmetric functions (in theory), avoid fragmentation, be > more deterministic, and a better fit for embedded applications. That could > then become the basis of the library for other projects too. > I think compared to our existing allocator, that would indeed be an improvement, and as you say possibly a "quick fix" for some of the performance issues of our asymmetric crypto (esp. ECC)... for people who use our allocator. I'm still under the impression they're a minority of users, even in the embedded world. I think it comes back to a point we touched on earlier in the thread: what other allocators are available, and how do they compare to the design you have in mind? If existing allocators in popular embedded libc implementations already handle small allocations efficiently, then people are probably better off using them. > I wouldn't mind contributing such a feature, as I had to write something very > similar last week anyway. > > If I do it - will you accept it? Thanks for the offer! Unfortunately I think it's hard to give you a clear yes or no answer at this point. Speaking only for myself (others in the team may disagree and are welcome to say so in reply), I'm a bit concerned that for a "quick fix" it would represent a significant review effort: there are obvious security implications, it would be a complete re-design of a whole module, and I'm not sure how many of the potential reviewers are very familiar with allocators (I know I'm not). Considering we already have a number of significant contributions that we just can't review as soon as we'd like, I'd be concerned adding another one. Adding to that concern is the fact that at this point it's still not clear to me if in the long-term we want to keep maintaining this, or use some existing allocator, or move it to a separate project possibly maintained by another team. Would your offer still stand in a couple of months, when the future of the module is perhaps a bit clearer, and when we've hopefully cleared a few of the long-standing large PR awaiting review? Thanks, Manuel.

5 years, 3 months

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Re: [mbed-tls] Fwd: MBEDTLS never exits ecp_double_jac function call

by Gilles Peskine

Hi Sirjee, Does this fail systematically or randomly? Can you reproduce this with a very small program that only opens a TLS connection and nothing else, like programs/ssl/ssl_client1? At a guess, but this is only a guess, maybe this is the part of your program which uses the largest amount of stack, and there's a stack overflow that causes some variable to be overwritten. Please try increasing the stack size. -- Gilles Peskine Mbed TLS developer P.S. The config.h attachment didn't come through, but a graphical signature did. Please check your email settings when posting to the list. On 04/05/2020 10:50, Sirjee Rooplall via mbed-tls wrote: > > > Hi Support, > > I am using MBEDTLS and most of it works, except I have hit a snag > where I am trying to communicate to an https server, and it fails in > the ssl->handshake-step (ssl_write_client_key_exchange). > > My stack trace shows that it gets to the function ecp_double_jac and > never exits. It is looping at > MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &P->X, &S ) ); > MOD_ADD( T );. > Stack trace: > test.elf! mbedtls_mpi_sub_abs (mbedtls_mpi * X, const mbedtls_mpi * A, > const mbedtls_mpi * B) Line: 1287 > test.elf! ecp_double_jac (const mbedtls_ecp_group * grp, > mbedtls_ecp_point * R, const mbedtls_ecp_point * P) Line: 1310 > test.elf! ecp_precompute_comb (const mbedtls_ecp_group * grp, > mbedtls_ecp_point * T, const mbedtls_ecp_point * P, unsigned char w, > size_t d, mbedtls_ecp_restart_ctx * rs_ctx) Line: 1702 > test.elf! ecp_mul_comb (mbedtls_ecp_group * grp, mbedtls_ecp_point * > R, const mbedtls_mpi * m, const mbedtls_ecp_point * P, int (*)(void *, > unsigned char *, size_t) f_rng, void * p_rng, mbedtls_ecp_restart_ctx > * rs_ctx) Line: 2095 > test.elf! mbedtls_ecp_mul_restartable (mbedtls_ecp_group * grp, > mbedtls_ecp_point * R, const mbedtls_mpi * m, const mbedtls_ecp_point > * P, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, > mbedtls_ecp_restart_ctx * rs_ctx) Line: 2396 > test.elf! ecdh_gen_public_restartable (mbedtls_ecp_group * grp, > mbedtls_mpi * d, mbedtls_ecp_point * Q, int (*)(void *, unsigned char > *, size_t) f_rng, void * p_rng, mbedtls_ecp_restart_ctx * rs_ctx) > Line: 84 > test.elf! mbedtls_ecdh_gen_public (mbedtls_ecp_group * grp, > mbedtls_mpi * d, mbedtls_ecp_point * Q, int (*)(void *, unsigned char > *, size_t) f_rng, void * p_rng) Line: 102 > test.elf! ecdh_make_public_internal (mbedtls_ecdh_context_mbed * > ctx, size_t * olen, int point_format, unsigned char * buf, size_t > blen, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, > int restart_enabled) Line: 514 > test.elf! mbedtls_ecdh_make_public (mbedtls_ecdh_context * ctx, > size_t * olen, unsigned char * buf, size_t blen, int (*)(void *, > unsigned char *, size_t) f_rng, void * p_rng) Line: 542 > test.elf! ssl_write_client_key_exchange (mbedtls_ssl_context * ssl) > Line: 3362 > test.elf! mbedtls_ssl_handshake_client_step (mbedtls_ssl_context * > ssl) Line: 4015 > test.elf! mbedtls_ssl_handshake_step (mbedtls_ssl_context * ssl) > Line: 9564 > test.elf! mbedtls_ssl_handshake (mbedtls_ssl_context * ssl) Line: 9588 > test.elf! https_do_tls_handshake (struct httpsConfigStr * client) > Line: 419 > test.elf! HttpsStateMachine Line: 366 > test.elf! HttpsTask (void * param) Line: 110 > test.elf! ?? Line: 110 > > MBEDTLS VERSION: mbed TLS 2.18.0 > PLATFORM: embedded microchip SAME70 micro controller. > > I have attached my config.h file. > > What am I doing wrong? > >

5 years, 3 months

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Fwd: MBEDTLS never exits ecp_double_jac function call

by Sirjee Rooplall

Hi Support, I am using MBEDTLS and most of it works, except I have hit a snag where I am trying to communicate to an https server, and it fails in the ssl->handshake-step (ssl_write_client_key_exchange). My stack trace shows that it gets to the function ecp_double_jac and never exits. It is looping at MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &P->X, &S ) ); MOD_ADD( T );. Stack trace: test.elf! mbedtls_mpi_sub_abs (mbedtls_mpi * X, const mbedtls_mpi * A, const mbedtls_mpi * B) Line: 1287 test.elf! ecp_double_jac (const mbedtls_ecp_group * grp, mbedtls_ecp_point * R, const mbedtls_ecp_point * P) Line: 1310 test.elf! ecp_precompute_comb (const mbedtls_ecp_group * grp, mbedtls_ecp_point * T, const mbedtls_ecp_point * P, unsigned char w, size_t d, mbedtls_ecp_restart_ctx * rs_ctx) Line: 1702 test.elf! ecp_mul_comb (mbedtls_ecp_group * grp, mbedtls_ecp_point * R, const mbedtls_mpi * m, const mbedtls_ecp_point * P, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, mbedtls_ecp_restart_ctx * rs_ctx) Line: 2095 test.elf! mbedtls_ecp_mul_restartable (mbedtls_ecp_group * grp, mbedtls_ecp_point * R, const mbedtls_mpi * m, const mbedtls_ecp_point * P, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, mbedtls_ecp_restart_ctx * rs_ctx) Line: 2396 test.elf! ecdh_gen_public_restartable (mbedtls_ecp_group * grp, mbedtls_mpi * d, mbedtls_ecp_point * Q, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, mbedtls_ecp_restart_ctx * rs_ctx) Line: 84 test.elf! mbedtls_ecdh_gen_public (mbedtls_ecp_group * grp, mbedtls_mpi * d, mbedtls_ecp_point * Q, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng) Line: 102 test.elf! ecdh_make_public_internal (mbedtls_ecdh_context_mbed * ctx, size_t * olen, int point_format, unsigned char * buf, size_t blen, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng, int restart_enabled) Line: 514 test.elf! mbedtls_ecdh_make_public (mbedtls_ecdh_context * ctx, size_t * olen, unsigned char * buf, size_t blen, int (*)(void *, unsigned char *, size_t) f_rng, void * p_rng) Line: 542 test.elf! ssl_write_client_key_exchange (mbedtls_ssl_context * ssl) Line: 3362 test.elf! mbedtls_ssl_handshake_client_step (mbedtls_ssl_context * ssl) Line: 4015 test.elf! mbedtls_ssl_handshake_step (mbedtls_ssl_context * ssl) Line: 9564 test.elf! mbedtls_ssl_handshake (mbedtls_ssl_context * ssl) Line: 9588 test.elf! https_do_tls_handshake (struct httpsConfigStr * client) Line: 419 test.elf! HttpsStateMachine Line: 366 test.elf! HttpsTask (void * param) Line: 110 test.elf! ?? Line: 110 MBEDTLS VERSION: mbed TLS 2.18.0 PLATFORM: embedded microchip SAME70 micro controller. I have attached my config.h file. What am I doing wrong?

5 years, 3 months

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Re: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code base

by Simon Butcher

Hi All, I appreciate I'm coming very late to this discussion, but I want to make a point and suggestion. The performance of the asymmetric functions is less than ideal, and whilst I think we can all agree that the ECC code should be rewritten at some point to be more competitive, one of the issues with the performance is that the MPI code uses malloc() a lot. There are competing crypto libraries out there that are faster and use a smaller RAM footprint and don't use dynamic memory allocation at all. Our memory allocation code is also kind of slow, and has a primitive and simplistic design of a linked list. These are very similar points to those Manuel was making to remove the feature in the first place - however - short of investing the time in rewriting the asymmetric functions, what we could do as a quick fix is to replace the existing memory code with a block allocation scheme - which should be much faster, speed up the asymmetric functions (in theory), avoid fragmentation, be more deterministic, and a better fit for embedded applications. That could then become the basis of the library for other projects too. I wouldn't mind contributing such a feature, as I had to write something very similar last week anyway. If I do it - will you accept it? Kind regards Simon On 09/04/2020, 12:07, "mbed-tls on behalf of Dan Handley via mbed-tls" <mbed-tls-bounces(a)lists.trustedfirmware.org on behalf of mbed-tls(a)lists.trustedfirmware.org> wrote: Hi There has already been some discussion about a shared C standard library implementation, at least for TF-A and TF-M. So far there's been general agreement that this is a good idea but no actual commitment from anyone to make this happen, since each project is reasonably happy with what they've got. Regarding MBEDTLS_MEMORY_BUFFER_ALLOC_C, TF-A at least enables this so removing this from the codebase would be an issue there. Memory allocators are probably not the core expertise of other Trusted Firmware projects either but it needs to be if they're going to use them! I propose that we move this allocator into a new shared TrustedFirmware.org standard C library project and work with the other projects to ensure it has the correct initial maintainers. This will probably have to be driven by the maintainers of whichever project is most motivated to make this happen. It sounds like that could be Mbed TLS and this will need to be done before any separation of the PSA Crypto implementation. In the short term, as we move C stdlib functionality out of the other projects and into this new project, we will need to support multiple implementations of some functions. Eventually we should move towards a common implementation, and I agree we should look at what security-oriented implementations are already available. I also agree it would make sense for Mbed TLS to not use the toolchain-provided stdlib implementation by default, but only once it uses a default implementation it trusts. Regards Dan. > -----Original Message----- > From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> On Behalf Of > Ronald Cron via mbed-tls > Sent: 09 April 2020 08:47 > To: mbed-tls(a)lists.trustedfirmware.org > Subject: Re: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code > base > > Hi, I think this is related to the more general need for an implementation of > the C standard library for trusted firmware projects. As far as I know TF-A > and TF-M don't use the standard library provided by compilation toolchains. > The rationale is to have complete control over the trusted firmware code. > Currently they both have their own partial implementation of the parts of the > C standard library they need. > > This memory_buffer_alloc.c module in question here is another partial > implementation of the C standard library. Currently TF-A and TF-M don't > use/provide dynamic memory allocations but PSA-FF explicitly mentions that an > SPM implementation may support dynamic memory allocation. Thus it is possible > that TF-M at some point consider providing dynamic memory allocation support. > > All of this to say that a possible way forward may be to remove > memory_buffer_alloc.c from the code base when there is a C standard library > implementation common to trustedfirmware.org projects (is there already a > security oriented open source implementation out there ?). > > In Mbed TLS, it would also make sense to me to, by default, not use C > standard libraries provided by compilation toolchains > (MBEDTLS_PLATFORM_NO_STD_FUNCTIONS defined by default). > > Thanks, Ronald. > > > -----Original Message----- > From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> On Behalf Of > Manuel Pegourie-Gonnard via mbed-tls > Sent: 08 April 2020 12:42 > To: mbed-tls(a)lists.trustedfirmware.org > Cc: nd <nd(a)arm.com> > Subject: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code > base > > Hi all, > > In this new installment of "let's discuss ideas for Mbed TLS 3.0" [1]: > should we remove memory_buffer_alloc.c from the code base? > > [1]: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ > > Currently the crypto library includes a module called memory_buffer_alloc.c, > disabled in the default build (config.h option MBEDTLS_MEMORY_BUFFER_ALLOC_C), > which provides implementations of calloc() and free() based on a user- > provided buffer (which could be static or on the stack), suitable for use in > the rest of the crypto, X.509 and TLS libraries as replacements to the > standard functions. > > In addition to providing replacement calloc() and free(), the module also > offers some facilities for measurement and debugging. > > We're considering dropping this module and removing it from the code base > entirely for the following reasons: > > - Memory allocators are not our core area of expertise. > > - This allocator is pretty basic and has a large allocation overhead. For > example for ECC computations, the overhead can be as large as the actual > memory used. > > - Using this allocator also tends to slow things down, so we don't run many > tests with it enabled. > > - In the future when we split between PSA Crypto on one side and Mbed TLS and > X.509 on the other, it's unclear on which side this allocator should fall. > Which can be taken as a sign that it doesn't really belong here. > > On the other hand, we're hesitating for the following reasons: > > - We know from bug reports and questions that some people are using it. > > - Unlike other modules we'd like to drop, there isn't a strong security > incentive to dropping this allocator, it's merely a matter of how we spend > our maintenance resources. > > What do you think? Should we keep maintaining this allocator as part of Mbed > TLS? Should we drop it and focus on our core instead? If you're using this > allocator, why did you pick it over other alternatives? > > Regards, > Manuel. > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls > IMPORTANT NOTICE: The contents of this email and any attachments are > confidential and may also be privileged. If you are not the intended > recipient, please notify the sender immediately and do not disclose the > contents to any other person, use it for any purpose, or store or copy the > information in any medium. Thank you. > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. -- mbed-tls mailing list mbed-tls(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls

5 years, 4 months

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Re: [mbed-tls] Development environment: minimum tool versions

by Gilles Peskine

On 25/04/2020 23:44, Steffan Karger via mbed-tls wrote: > Hi, > > I maintain OpenVPN-NL (https://openvpn.fox-it.com), which uses mbedtls > as it's crypto library. > > On 24-04-2020 00:25, Gilles Peskine via mbed-tls wrote: >> 1. Is there any interest in the community for making sure that the build >> keeps (or starts) working on RHEL 6? > Yes, we support RHEL6 until it's retirement (30 November 2020). (…) > It would be nice if it's at least possible to build mbedtls on/for these > platforms until they go out of regular support. Preferably with their > default packages compilers. > All right, thanks for the feedback! I'm not going to promise that we'll add RHEL 6 to our CI. (Of course, in TrustedFirmware, it can happen if someone's motivated enough to contribute it and to keep maintaining it.) But let's at least not knowingly break support for CMake 2.8 yet (or GNU make 3.81 or older GCC and Clang but those are less likely to break). I expect that it will remain possible to build the library *for* ancient systems for a very long time, since all it really needs is a basic C runtime. But the tooling to build the library, or at least to do anything more than building the library (tuning the configuration, building and running tests, etc.) is slowly modernizing (the configuration script and the test building script have required Python 3 for a while now). -- Gilles Peskine Mbed TLS developer

5 years, 4 months

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ECDH Computation on STM32 platform

by Abhilash Iyer

Hello, I am trying to do the ECDH shared secret computation using the mbedTLS library. I am referring to multiple examples such as ecdh_curve25519.c<https://github.com/ARMmbed/mbedtls/blob/development/programs/pkey/ecdh_curv…> and ecdh_main.c<https://github.com/SiliconLabs/peripheral_examples/blob/master/series2/se/s…>. In my case, in my application firmware, I already have a device _priv key and I receive a server_public key; both generated using a curve ECP_DP_SECP256R1 in the bootloader itself. So in the application firmware, I would like to do generate a shared secret from here on and preserve it for future use. The following is the steps that I do: 1. Create a new client context, entropy context, ctr_drbg context variables. 2. use mbedtls_"respective"_init() to initalize all the three variables 3. Seed a random number using mbedtls_ctr_drbg_seed() function. 4. load the P256 elliptic curve in client context using mbedtls_ecp_group_load() 5. Then use mbedtls_mpi_lset() to set Qp.Z =1 6. Then read the server pub key using mbedtls_mpi_read_binary(&ctx_cli.Qp.X, server_pub, 65); 7. Now the question is: Should I initialize the ctx_cli with my already generated device_priv key using mbedtls_mpi_read_binary(&ctx_cli.d, device_priv_key, 50) ? 8. Then I use mbedtls_ecdh_compute_shared(&ctx_cli.grp, &ctx_cli.z, &ctx_cli.Qp, &ctx_cli.d, mbedtls_ctr_drbg_random, &ctr_drbg); to compute the shared secret in z. Questions: 1. Do I need to generate a keypair for client context using mbedtls_ecdh_gen_public(&ctx_cli.grp, &ctx_cli.d, &ctx_cli.Q, mbedtls_ctr_drbg_random, &ctrDrbg)? And then set pvtkey as device priv key and pub key as service pub key? 2. I see that ctx_cli.Q has two components, Q.x and Q.y. How do I extract these two values from a public key? Do I need to separately initialize them? Please let me know if the flow is correct. In all the examples, they generate a key pair and just update the public key part (Qp.X) of the key. They do not touch the private key part (d) of the key. Please confirm if I can upload my private key directly in my case. Also if my platform is a little endian, is there a recommended step before using mbedtls_mpi_read_binary_le functions? Thanks so much for your help in advance! Thanks, Abhilash From: Abhilash Iyer Sent: Monday, April 27, 2020 11:25 AM To: mbed-tls(a)lists.trustedfirmware.org Subject: Hello, I am trying to do the ECDH shared secret computation using the mbedTLS library. I am referring to multiple examples such as ecdh_curve25519.c<https://github.com/ARMmbed/mbedtls/blob/development/programs/pkey/ecdh_curv…> and ecdh_main.c<https://github.com/SiliconLabs/peripheral_examples/blob/master/series2/se/s…>. In my case, in my application firmware, I already have a device _priv key and I receive a server_public key; both generated using a curve ECP_DP_SECP256R1 in the bootloader itself. So in the application firmware, I would like to do generate a shared secret from here on and preserve it for future use. The following is the steps that I do: 1. Create a new client context, entropy context, ctr_drbg context variables. 2. use mbedtls_"respective"_init() to initalize all the three variables 3. Seed a random number using mbedtls_ctr_drbg_seed() function. 4. load the P256 elliptic curve in client context using mbedtls_ecp_group_load() 5. Then use mbedtls_mpi_lset() to set Qp.Z =1 6. Then read the server pub key using mbedtls_mpi_read_binary(&ctx_cli.Qp.X, server_pub, 65); 7. Now the question is: Should I initialize the ctx_cli with my already generated device_priv key using mbedtls_mpi_read_binary(&ctx_cli.d, device_priv_key, 50) ? 8. Then I use mbedtls_ecdh_compute_shared(&ctx_cli.grp, &ctx_cli.z, &ctx_cli.Qp, &ctx_cli.d, mbedtls_ctr_drbg_random, &ctr_drbg); to compute the shared secret in z. Questions: 1. Do I need to generate a keypair for client context using mbedtls_ecdh_gen_public(&ctx_cli.grp, &ctx_cli.d, &ctx_cli.Q, mbedtls_ctr_drbg_random, &ctrDrbg)? And then set pvtkey as device priv key and pub key as service pub key? 2. I see that ctx_cli.Q has two components, Q.x and Q.y. How do I extract these two values from a public key? Do I need to separately initialize them? Please let me know if the flow is correct. In all the examples, they generate a key pair and just update the public key part (Qp.X) of the key. They do not touch the private key part (d) of the key. Please confirm if I can upload my private key directly in my case. Also if my platform is a little endian, is there a recommended step before using mbedtls_mpi_read_binary_le functions? Thanks so much for your help in advance! Thanks, Abhilash Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

5 years, 4 months

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Re: [mbed-tls] Random Number Generator module in mbed TLS

by ROSHINI DEVI

Perfect! Thanks everyone for your assistance. On Tue, Apr 28, 2020 at 1:48 PM Janos Follath via mbed-tls < mbed-tls(a)lists.trustedfirmware.org> wrote: > Hi, > > > > Hanno described perfectly how it works and I just would like to add a > single remark. You mentioned that some of your platforms don’t have a > hardware entropy source. In cases like that, depending on your threat model > you might need to use the MBEDTLS_ENTROPY_NV_SEED feature to achieve > security. > > > > (This uses a stored secret value as a seed and on embedded systems without > a hardware entropy source it is more secure against a remote adversary than > trying to collect the entropy from the environment. On systems like that > NV_SEED can have an edge against physical attackers – compared to > attempting to collect entropy from the environment – if the seed is stored > in secure storage/internal flash.) > > > > Regards, > > Janos > > > > *From: *mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf > of Hanno Becker via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> > *Reply to: *Hanno Becker <Hanno.Becker(a)arm.com> > *Date: *Tuesday, 28 April 2020 at 07:55 > *To: *"mbed-tls(a)lists.trustedfirmware.org" < > mbed-tls(a)lists.trustedfirmware.org>, ROSHINI DEVI <roshinilachi(a)gmail.com> > *Subject: *Re: [mbed-tls] Random Number Generator module in mbed TLS > > > > Hi, > > > > Mbed TLS establishes variable-length access to random data in a three step > fashion: > > > > 1) At the bottommost layer, there is a variable number of *entropy > sources *external to the library. > > Such sources are supposed to provide some true randomness, though the > exact amount of > > entropy they contain isn't yet specified (at least to my knowledge). > > > > 2) Mbed TLS' entropy module mixes those entropy sources into a single > source of randomness. > > In contrast to the entropy sources themselves, the idea here is that, > ideally, the data obtained > > from the entropy module has full entropy. This is achieved by (a) > accumulating random data > > from available entropy sources and depending on the amount of entropy each > of them offers, > > and (b) 'mixing' them by a application of hash functions. > > > > 3) Based on true randomness, Mbed TLS' provides two implementations of > pseudo random > > number generators: CTR-DRBG and HMAC-DRBG. Those build on top of an > entropy context > > and expand the underlying randomness as standardized in NIST SP 800-90. > > > > Applications should use the PRNGs from step 3) as their actual source of > randomness, > > and not directly hook into the underlying TRNGs. > > > > Take a look at the example programs such as `ssl_client2` or `ssl_server2` > to see how this > > works practically. Also see > https://tls.mbed.org/kb/how-to/add-a-random-generator. > > > > Now specifically to your question: You should register your STM32 hardware > entropy > > as an entropy source via `mbedtls_entropy_add_source()` but not (need) to > change > > anything else in your code. In particular, steps 2) and 3) above are > entirely independent > > of the exact source of true randomness. > > > > Hope this helps, > > > > Hanno > > > ------------------------------ > > *From:* mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf > of ROSHINI DEVI via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> > *Sent:* Tuesday, April 28, 2020 6:06 AM > *To:* mbed-tls(a)lists.trustedfirmware.org < > mbed-tls(a)lists.trustedfirmware.org> > *Subject:* Re: [mbed-tls] Random Number Generator module in mbed TLS > > > > Hello, > > > > Can anyone confirm this? Its urgent. > > > > Thanks > > > > On Fri, Apr 17, 2020 at 4:50 PM ROSHINI DEVI <roshinilachi(a)gmail.com> > wrote: > > Hello, > > > > Is there any random number library available in mbedTLS? > > Right now, I am using hardware entropy in STM32 boards. > > If hardware platform changes and if there is no hardware entropy present, > then again we need to redefine the API. > > > > Thanks > > IMPORTANT NOTICE: The contents of this email and any attachments are > confidential and may also be privileged. If you are not the intended > recipient, please notify the sender immediately and do not disclose the > contents to any other person, use it for any purpose, or store or copy the > information in any medium. Thank you. > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls >

5 years, 4 months

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Re: [mbed-tls] Random Number Generator module in mbed TLS

by Janos Follath

Hi, Hanno described perfectly how it works and I just would like to add a single remark. You mentioned that some of your platforms don’t have a hardware entropy source. In cases like that, depending on your threat model you might need to use the MBEDTLS_ENTROPY_NV_SEED feature to achieve security. (This uses a stored secret value as a seed and on embedded systems without a hardware entropy source it is more secure against a remote adversary than trying to collect the entropy from the environment. On systems like that NV_SEED can have an edge against physical attackers – compared to attempting to collect entropy from the environment – if the seed is stored in secure storage/internal flash.) Regards, Janos From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Hanno Becker via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Reply to: Hanno Becker <Hanno.Becker(a)arm.com> Date: Tuesday, 28 April 2020 at 07:55 To: "mbed-tls(a)lists.trustedfirmware.org" <mbed-tls(a)lists.trustedfirmware.org>, ROSHINI DEVI <roshinilachi(a)gmail.com> Subject: Re: [mbed-tls] Random Number Generator module in mbed TLS Hi, Mbed TLS establishes variable-length access to random data in a three step fashion: 1) At the bottommost layer, there is a variable number of entropy sources external to the library. Such sources are supposed to provide some true randomness, though the exact amount of entropy they contain isn't yet specified (at least to my knowledge). 2) Mbed TLS' entropy module mixes those entropy sources into a single source of randomness. In contrast to the entropy sources themselves, the idea here is that, ideally, the data obtained from the entropy module has full entropy. This is achieved by (a) accumulating random data from available entropy sources and depending on the amount of entropy each of them offers, and (b) 'mixing' them by a application of hash functions. 3) Based on true randomness, Mbed TLS' provides two implementations of pseudo random number generators: CTR-DRBG and HMAC-DRBG. Those build on top of an entropy context and expand the underlying randomness as standardized in NIST SP 800-90. Applications should use the PRNGs from step 3) as their actual source of randomness, and not directly hook into the underlying TRNGs. Take a look at the example programs such as `ssl_client2` or `ssl_server2` to see how this works practically. Also see https://tls.mbed.org/kb/how-to/add-a-random-generator. Now specifically to your question: You should register your STM32 hardware entropy as an entropy source via `mbedtls_entropy_add_source()` but not (need) to change anything else in your code. In particular, steps 2) and 3) above are entirely independent of the exact source of true randomness. Hope this helps, Hanno ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of ROSHINI DEVI via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: Tuesday, April 28, 2020 6:06 AM To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: Re: [mbed-tls] Random Number Generator module in mbed TLS Hello, Can anyone confirm this? Its urgent. Thanks On Fri, Apr 17, 2020 at 4:50 PM ROSHINI DEVI <roshinilachi(a)gmail.com<mailto:roshinilachi@gmail.com>> wrote: Hello, Is there any random number library available in mbedTLS? Right now, I am using hardware entropy in STM32 boards. If hardware platform changes and if there is no hardware entropy present, then again we need to redefine the API. Thanks IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] Random Number Generator module in mbed TLS

by Hanno Becker

Hi, Mbed TLS establishes variable-length access to random data in a three step fashion: 1) At the bottommost layer, there is a variable number of entropy sources external to the library. Such sources are supposed to provide some true randomness, though the exact amount of entropy they contain isn't yet specified (at least to my knowledge). 2) Mbed TLS' entropy module mixes those entropy sources into a single source of randomness. In contrast to the entropy sources themselves, the idea here is that, ideally, the data obtained from the entropy module has full entropy. This is achieved by (a) accumulating random data from available entropy sources and depending on the amount of entropy each of them offers, and (b) 'mixing' them by a application of hash functions. 3) Based on true randomness, Mbed TLS' provides two implementations of pseudo random number generators: CTR-DRBG and HMAC-DRBG. Those build on top of an entropy context and expand the underlying randomness as standardized in NIST SP 800-90. Applications should use the PRNGs from step 3) as their actual source of randomness, and not directly hook into the underlying TRNGs. Take a look at the example programs such as `ssl_client2` or `ssl_server2` to see how this works practically. Also see https://tls.mbed.org/kb/how-to/add-a-random-generator. Now specifically to your question: You should register your STM32 hardware entropy as an entropy source via `mbedtls_entropy_add_source()` but not (need) to change anything else in your code. In particular, steps 2) and 3) above are entirely independent of the exact source of true randomness. Hope this helps, Hanno ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of ROSHINI DEVI via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: Tuesday, April 28, 2020 6:06 AM To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: Re: [mbed-tls] Random Number Generator module in mbed TLS Hello, Can anyone confirm this? Its urgent. Thanks On Fri, Apr 17, 2020 at 4:50 PM ROSHINI DEVI <roshinilachi(a)gmail.com<mailto:roshinilachi@gmail.com>> wrote: Hello, Is there any random number library available in mbedTLS? Right now, I am using hardware entropy in STM32 boards. If hardware platform changes and if there is no hardware entropy present, then again we need to redefine the API. Thanks IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Random Number Generator module in mbed TLS

by ROSHINI DEVI

Hello, Is there any random number library available in mbedTLS? Right now, I am using hardware entropy in STM32 boards. If hardware platform changes and if there is no hardware entropy present, then again we need to redefine the API. Thanks

5 years, 4 months

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Edwards curve support (#3245): fixing mbedtls_ecp_get_type

by Aurelien Jarno

Hi all, I have submitted PR#3245 in order to add Edwards curves support to Mbed TLS, with the eventual goal to add support for the EdDSA algorithm. There are still a few things to fix that require discussion. Let's start the discussion with the first one. Adding a new curve type requires to add a new entry to the mbedtls_ecp_curve_type enum. The curve type used by a group is returned by the mbedtls_ecp_get_type function. It currently uses the coordinates type of the base point to determine the curve type. Montgomery curves are lacking the y coordinate, and the Short Weierstrass curves use the three x, y and z coordinates. The Edwards arithmetic implementation in this PR uses the projective coordinates. As such it also uses the x, y and z coordinates and this gives no way to differentiate a Short Weierstrass from an Edwards curve. I have currently implemented that by checking if the curves are the Ed25519 or Ed448 ones using the group id [1]. I am not sure it's very clean and it won't scale if more curves are added later. Another alternative would be to add another entry to mbedtls_ecp_group to hold the curve type. What do you think is the best option? Any other idea? Thanks, Aurelien [1] https://github.com/ARMmbed/mbedtls/pull/3245/commits/aa20cf122a1a54cfa23624… -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien(a)aurel32.net http://www.aurel32.net

5 years, 4 months

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Re: [mbed-tls] Development environment: minimum tool versions

by Steffan Karger

Hi, I maintain OpenVPN-NL (https://openvpn.fox-it.com), which uses mbedtls as it's crypto library. On 24-04-2020 00:25, Gilles Peskine via mbed-tls wrote: > 1. Is there any interest in the community for making sure that the build > keeps (or starts) working on RHEL 6? Yes, we support RHEL6 until it's retirement (30 November 2020). > 2. Is there any interest in the community for making sure that the build > keeps working on Ubuntu 16.04? Yes, we support all Ubuntu LTS versions until their standard support ends (April 2021 for 16.04). > 3. Are there any other "old" platforms that we should consider? All Debian and SLES versions that are still in regular maintance (ie, not including any "extended security maintenance" support). It would be nice if it's at least possible to build mbedtls on/for these platforms until they go out of regular support. Preferably with their default packages compilers. SLES/RHEL are the most demanding, with their 10 year support cycle. Thanks, -Steffan

5 years, 4 months

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Re: [mbed-tls] RSA key generation issue

by Gilles Peskine

Hi Nazar, On 24/04/2020 10:22, Nazar Chornenkyy via mbed-tls wrote: > > On the PSoC6 device we are using mbedtls_rsa_gen_key function with a > good hardware TRNG passed FIPS 140-2 verification. > > This function verifies generated random pair and requests new pair if > they don’t follow FIPS 186-4 criteria. > > The number of verification loops is between 1 and 6 in worst case. > > Is it expected behavior? > > The arithmetic of one loop takes a lots of time. > > How can we improve the random number to have always pass FIPS 186-4 in > a one loop? > I'm not sure what you're doing. Are you calling mbedtls_rsa_gen_key() multiple times and rejecting the key if it doesn't pass additional checks? Or are you just calling it once? As far as I know, mbedtls_rsa_gen_key() follows the procedure described in FIPS 186-4 (which is compatible with previous versions of FIPS 186), and no additional checks should be needed. If you're calling it once and observing that it tries multiple values of p and q before finding a suitable one, this is expected behavior. There's no way to "improve" the random numbers to make it faster: the probability that a pair of (probabilistic) primes can work together as an RSA key is less than 1. I don't know the math off the top of my head, but 1–6 tries seems reasonable. Key generation is the slowest of the RSA operations. If that's a problem in your application, consider using elliptic curve cryptography instead. ECC has very fast key generation, faster private key operations (signature, decryption) than RSA, and smaller keys. The main benefit of RSA is that public key operations (verification, encryption) are faster. -- Gilles Peskine Mbed TLS developer IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Development environment: minimum tool versions

by Gilles Peskine

Hello, I'm starting this thread to get input from the community about what versions of compilers and other build tools Mbed TLS should support. We of course strive to remain compatible with the latest versions, so this discussion is about support for older versions. We currently don't really have an official version range for the build dependencies of Mbed TLS: * C compilers (GCC, Clang, Arm Compiler, IAR, Visual Studio) * Build tools (GNU make, CMake) * Scripting tools (shell, Perl, Python) In practice, for the past three years or so, most of our continuous integration has been running on Ubuntu 16.04, so we mostly test with GCC 5.4.0, Clang 3.8, GNU make 4.1, CMake 3.5.1 and Python 3.5. (For shell and Perl, even pretty ancient version should work.) For Arm Compiler (armcc/armclang) and IAR, we use the same version as Mbed OS. On Windows, we currently test Visual Studio 2013, 2015 and 2017, as well as a version of Mingw that's changed more quickly than most of the rest of our CI. We also run some tests on FreeBSD (a bit more recent that the Ubuntu machines). The top-level CMakeLists.txt has conditionals that detect much older versions of CMake, GCC and Clang, but we haven't tested those in ages and we don't really know if, for example, the library still builds with CMake 2.8 and GCC 4.2. As part of the move of the project from Arm to Trusted Firmware, we'll change our CI infrastructure, and this may or may not mean we end up testing with different versions. In https://github.com/ARMmbed/mbedtls/issues/2896 I looked at the software versions in some common "slow updating" operating systems: RHEL/Centos, Ubuntu LTS. 1. Is there any interest in the community for making sure that the build keeps (or starts) working on RHEL 6? 2. Is there any interest in the community for making sure that the build keeps working on Ubuntu 16.04? 3. Are there any other "old" platforms that we should consider? 4. Should we consider older compilers (maybe some platforms are stuck with older versions of GCC)? 5. On Windows, what's the oldest version of Visual Studio we should keep compatibility with? -- Gilles Peskine Mbed TLS developer IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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RSA key generation issue

by Nazar Chornenkyy

Hi I found this email on ARM MBED support forum. Could you help to resolve our issue? On the PSoC6 device we are using mbedtls_rsa_gen_key function with a good hardware TRNG passed FIPS 140-2 verification. This function verifies generated random pair and requests new pair if they don't follow FIPS 186-4 criteria. The number of verification loops is between 1 and 6 in worst case. Is it expected behavior? The arithmetic of one loop takes a lots of time. How can we improve the random number to have always pass FIPS 186-4 in a one loop? Thanks Nazar This message and any attachments may contain confidential information from Cypress or its subsidiaries. If it has been received in error, please advise the sender and immediately delete this message.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move net.c out of the library

by Gilles Peskine

Like with timing (see my message in the timing thread, https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000061.html), I have a strong preference for the library to be usable out of the box on typical platforms. This means keeping the abstractions that are currently in the net_sockets module, or similar abstractions. This doesn't mean keeping the net_sockets module as such: these abstractions could be in platform.c. I lean towards having a platform_posix.c and a platform_windows.c (and any other we care to support), chosen at build time based on the target platform. I'm not sure exactly what they should look like. In particular, if you have an embedded platform that's sort of POSIX-like, but doesn't have every POSIX feature and does a few differently, should you be able to customize platform_posix.c through #defines, or should you copy it and modify it to suit your platform? -- Gilles Peskine Mbed TLS developer On 20/04/2020 11:52, Manuel Pegourie-Gonnard via mbed-tls wrote: > Hi all, > > [ Context: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ ] > > Currently the SSL/TLS library includes a module called net_sockets.c (formerly > net.c), enabled by default in config.h (but disabled by config.py baremetal), > that contains some networking functions based on POSIX or Windows sockets, > including functions suitable for use as I/O callbacks with our SSL/TLS > modules. > > Those functions are used only in example/testing programs, but nowhere in the > library itself. > > In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, > we're considering removing (parts of) this module from the library, and > moving its parts to a variety of other places, such as example programs (or > a library/file shared by them, like the current query_config mechanism). > > Reasons for removing this module from the library include: > > - overall the module is less portable and perhaps of lesser quality than the > rest of the library > - it's currently entirely untested on Windows (despite being very > platform-specific) > - there are often confusions about whether the module is meant to be a > general-purpose networking library, or just provide basic support for our > example and test, as well a simple prototypes > - it's not our core area of expertise, let's do one thing and to it well > > Reasons for keeping (parts of) it in the library include: > > - having mbedtls_net_recv{,_timeout}() and mbedtls_net_send() available right > in the library makes it easier to test and develop prototype > - this module is listed as a component in our high-level design document [2], > so perhaps removing it from the library can be seen as a bigger change? > > [2]: https://tls.mbed.org/high-level-design > > What do you think? Should we remove the entire module from the library, keep > it all, or just keep some parts? In that case, which parts and where? > > Regards, > Manuel. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move timing.c out of the library

by Gilles Peskine

I have a strong preference for the library, the tests and companion programs to build out of the box on officially supported platforms. On platforms that don't work out of the box, users should be able to drop in platform support code in the form of #defines or extra modules to link with. Ok, we don't have an official list of supported platforms. But inasmuch as we do have officially supported platforms, they include Linux and other modern Unix-like or POSIX environments, Windows, and Mbed OS. Mbed OS is a special case because Mbed TLS is part of the build tree there, so the mbedtls tree doesn't have to contain Mbed OS support. This doesn't mean that the library should have a timing module. I think the timing wrappers that the library needs, i.e. mbedtls_timing_{get,set}_delay, should be in platform.c. For platform features that are only used by test or sample programs, I think we should have a separate platform support file, and separate #defines so that you can build the library even if you can't build all the programs. For example, it makes sense to build DTLS support without having the timing functions used by the benchmark program. -- Gilles Peskine Mbed TLS developer On 21/04/2020 10:46, Manuel Pegourie-Gonnard via mbed-tls wrote: > Hi all, > > So personally I'm quite strongly inclined to remove timing.c from the > library, and move most of its content elsewhere, with one possible > exception: > >> - mbedtls_timing_set_delay() and mbedtls_timing_get_delay() are an example >> implementation (only for Unix and Windows) of timer callbacks for DTLS, only >> used in programs/ssl/*.c > Since timer callbacks are a hard requirement for using DTLS, and it seems > quite desirable to be able to support DTLS out of the box at least on > some platforms, I was thinking this pair of function (and the associated > context type) could be kept in the library, in a new module that would > be called something like ssl_dtls_timer.c. > > This would be somewhat similar to ssl_cookies.c, ssl_tickets.c and > ssl_cache.c: they all provide implementations of callbacks that can be > used with the main SSL/(D)TLS module, but users are obviously free to > compile them out and use their own implementation if the one we provide > does not meet their needs. > > As it happens, all three of these support modules work best if > MBEDTLS_HAVE_TIME is defined, but can work without it. > > For the new ssl_dtls_timer.c I'm suggesting, the situation would be > different: the module could have a hard dependency on MBEDTLS_HAVE_TIME, > but work better on selected platforms (say, C11, POSIX and > Windows) where we know how to access sub-second timing information. (Or > alternatively, have a hard dependency on C11-or-Posix-or-Windows.) > > For the record, mbedtls_ssl_conf_handshake_timeout() accepts timeout > values in milliseconds, but recommended values for use over the general > internet start at 1 second: > https://tools.ietf.org/html/rfc6347#section-4.2.4.1 > So it might make sense to provide this module even when we only have > second resolution - we'd just have to work out how the timer function > would behave when passed sub-second values. (My first thought it > rounding up to the next second would be quite OK.) > > What do you'all think? Personnally, I don't have a strong opinion > between the three following options, though I have a slight preference > for the first one: > > 1. Provide ssl_dtls_timer.c in the library with hard dep on HAVE_TIME > and enhanced features with C11/Posix/Windows. > 2. Provide ssl_dtls_timer.c in the library with hard dep on > C11/Posix/Windows. > 3. Move it all out of the library and let the thing live somewhere under > programs/ as it's only used by example/testing programs. > > Note though that we could also choose to go with option 3 for Mbed TLS > 3.0, see how it goes, and later switch to option 2 or 1 if we want, as > adding modules can be done at any time. (In the same vein, we could > start with 2 and switch to 1 at any time as well.) > > Regards, > Manuel. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move timing.c out of the library

by Manuel Pegourie-Gonnard

Hi, > [I'm assuming didn't mean to reply on the list and not just to me, so I'm replying on the list.] Oops, I misinterpreted the information presented by my mail client, you did reply on the list. Sorry for the noise (and for breaking the thread by not replying to the correct email.) Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move net.c out of the library

by Manuel Pegourie-Gonnard

Hi again, In the first email of the thread I tried giving a fair exposition of the question, now I'm going to give my personal opinion. Similarly to what I suggested for timing.c, I'm inclined to remove net.c as such, move most of its content (net_bind(), net_accept(), etc.) out of the library (most probably into a new file in programs/ssl, shared by SSL examples), and keep in the library only the 3 functions that can be used as SSL callbacks (and a supporting context type), but in a new module named for example ssl_io_sockets.c. This would also be similar to the other SSL modules that provide a reference/example implementation of some SSL callback but can easily be disabled (or jsut disregarded) in favour of a custom implementation for custom needs or unsupported platforms. Just like the current net_sockets.c, this new reduced module would probably only be supported on platforms with sockets, which is Posix platforms and Windows. Advantages include: - Reduce the amount of code and API surface in the library. Things like binding and accepting are hardly related to (D)TLS so there is little justification for having them in the library. Also, things in the library are bound by API stability rules which are sometimes a constraint. - It would clarify that we're not providing a general-purpose socket abstraction, as general socket management would be out of the library, and only the bits for plugging a socket into our SSL layer would be in the library. - (By the way currently net_sockets.h includes ssl.h, so it's already quite specific to our SSL module rather than generic, but moving the remaining bits of it into the SSL namespace would make that clearer.) - User would still have the convenience (on supported platforms) of ready-for-use callbacks. If you have an application already working with sockets without TLS, then we provide all the bits needed to turn that into an application using TLS on top of those sockets. I think that would be a good compromise between convenience for users, and reduced surface for the library. Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move certs.c out of the library

by Hanno Becker

Hi, I support this. Could certs.c live in `tests/data_files`? We should also make sure this file is automatically synced with the actual CRT and key files in that directory. There is a script which does that, but IIRC it's not called as part of the CI, which lead to certs.c and the data files get out of sync multiple times in the past. Best Hanno ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Manuel Pegourie-Gonnard via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: Monday, April 20, 2020 10:49 AM To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Cc: nd <nd(a)arm.com> Subject: [mbed-tls] 3.0 plans - move certs.c out of the library Hi all, In this new installment of "let's discuss ideas for Mbed TLS 3.0" [1]: should we move certs.c out of the library? [1]: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ Currently the X.509 library includes test certificates and keys, which are enabled by default in config.h - `MBEDTLS_CERTS_C`. These are used in the following places: - in library/x509.c in mbedtls_x509_self_test() - in tests/suites/test_suite_ssl.function - in programs/fuzz and programs/ssl In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, we'd like to remove certs.h and the certificates it contains from the library (except perhaps one static cert for mbedtls_x509_self_test()). Tests and example programs that need built-in certificates could still get them using any mechanism, included a file certs.c similar to the current one - but this file would no longer live in library or be included when building libmbedx509. Reasons include: - Including test certificates and keys in the library provides little value, as users will want to use their own certificates and keys anyway. - Shipping private keys as part of the library is bad practice, even under the `mbedtls_test_` sub-namespace. There's a slight risk that some users could use them for prototyping and then inadvertently keep using unsafe private keys in production. If you disagree or have concerns, please speak up! Also, if want to suggest ideas for where the replacement to library/certs.c should live or how it could be maintained, now's a good time as well! Regards, Manuel. -- mbed-tls mailing list mbed-tls(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move timing.c out of the library

by Manuel Pegourie-Gonnard

Hi all, So personally I'm quite strongly inclined to remove timing.c from the library, and move most of its content elsewhere, with one possible exception: > - mbedtls_timing_set_delay() and mbedtls_timing_get_delay() are an example > implementation (only for Unix and Windows) of timer callbacks for DTLS, only > used in programs/ssl/*.c Since timer callbacks are a hard requirement for using DTLS, and it seems quite desirable to be able to support DTLS out of the box at least on some platforms, I was thinking this pair of function (and the associated context type) could be kept in the library, in a new module that would be called something like ssl_dtls_timer.c. This would be somewhat similar to ssl_cookies.c, ssl_tickets.c and ssl_cache.c: they all provide implementations of callbacks that can be used with the main SSL/(D)TLS module, but users are obviously free to compile them out and use their own implementation if the one we provide does not meet their needs. As it happens, all three of these support modules work best if MBEDTLS_HAVE_TIME is defined, but can work without it. For the new ssl_dtls_timer.c I'm suggesting, the situation would be different: the module could have a hard dependency on MBEDTLS_HAVE_TIME, but work better on selected platforms (say, C11, POSIX and Windows) where we know how to access sub-second timing information. (Or alternatively, have a hard dependency on C11-or-Posix-or-Windows.) For the record, mbedtls_ssl_conf_handshake_timeout() accepts timeout values in milliseconds, but recommended values for use over the general internet start at 1 second: https://tools.ietf.org/html/rfc6347#section-4.2.4.1 So it might make sense to provide this module even when we only have second resolution - we'd just have to work out how the timer function would behave when passed sub-second values. (My first thought it rounding up to the next second would be quite OK.) What do you'all think? Personnally, I don't have a strong opinion between the three following options, though I have a slight preference for the first one: 1. Provide ssl_dtls_timer.c in the library with hard dep on HAVE_TIME and enhanced features with C11/Posix/Windows. 2. Provide ssl_dtls_timer.c in the library with hard dep on C11/Posix/Windows. 3. Move it all out of the library and let the thing live somewhere under programs/ as it's only used by example/testing programs. Note though that we could also choose to go with option 3 for Mbed TLS 3.0, see how it goes, and later switch to option 2 or 1 if we want, as adding modules can be done at any time. (In the same vein, we could start with 2 and switch to 1 at any time as well.) Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move timing.c out of the library

by Manuel Pegourie-Gonnard

Hi Torsten, [I'm assuming didn't mean to reply on the list and not just to me, so I'm replying on the list.] > On 20/04/2020 11:51, Manuel Pegourie-Gonnard via mbed-tls wrote: >> For reference, this module includes the following functions, which are used >> in the following places: >> >> - mbedtls_timing_hardclock() implements cycle counting (on selected >> architectures, not including M-class), used only in >> programs/test/benchmark.c > > I used mbedtls_timing_hardclock() for my own benchmarking experiments on > Linux and Windows, but couldn't get it to run on the target machine. So > I've use my own ms counter instead. So, it could be easily removed as > part of the library. > Good to know, thanks for sharing this data point. > Question: How do you want to do the benchmarking instead? With the same > code, but outside the library? > Yes, I was thinking that the functions that are only used in benchmark.c could be defined in benchmark.c, and the functions that are only used in udp_proxy.c could be defined in udp_proxy.c. (Or actually for the latter, we might want to start using them in ssl_client2.c and ssl_server2.c as well, as including millisecond timestamps in the debug output would be usefull to debug some issues. In that case, we'll probably put those functions in a new file, used by udp_proxy, ssl_client2 and ssl_server2 (just like query_config.c is currently used by ssl_client2, ssl_server2 and query_compile_time_config).) Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] Some thoughts towards mbed TLS 3.0

by Manuel Pegourie-Gonnard

Hi Torsten, > this will be a long mail. Sorry for that. > On the contrary, thank you so much for this extensive and well though-out feedback, that's very helpful! I'll try to complement Gilles's reply, and skip the points he already answered unless I have something to add, as I'm generally in full agreement with what he wrote. > 3. For certification and evaluation purposes I need some test vectors > for each crypto function on target. While I know about the > comprehensive self-test program I'm now talking about built-in > functions like mbedtls_sha512_self_test(), etc to be enabled with > #define MBEDTLS_SELF_TEST. > > These self-tests are very different in coverage. For SHA-384 and > SHA-512 they are fine, for HMAC-SHA-384 and HMAC-SHA-512 I couldn't > find any as well as for HKDF-HMAC-SHA-256 (in RFC 5869) or > HKDF-HMAC-SHA-384/512 (official test vectors difficult to find). > AES-CTR and AES-XTS are only tested with key length 128 bit, not with > 256 bit. AES-CCM is not tested with 256 bit and even for 128 bit, > the test vector from the standard NIST SP 800-38C with long > additional data is not used. > The builtin self-test for GCM is the best I've seen with mbedtls: > all three key lengths are tested as well as the IUF-interface and > the comfort function. Bravo! > Indeed so far we don't have clear guidelines on self-test functions, and we should try to have more consistency here. Since this is incremental, backwards-compatible improvements, it can be done at any time (unlike some API improvements that can only be done when preparing major versions). Contributions in this area are certainly welcome! > 7. While at Elliptic Curve Cryptography: I assume that some of you > know that projectives coordinates as outer interface to ECC are > dangerous, see David Naccache, Nigel P. Smart, Jacques Stern: > Projective Coordinates Leak, Eurocrypt 2004, pp. 257–267. Yes, and as it happens this was revisited recently by researchers, and brought back to our attention: https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advi… > you have Jacobian coordinates, i.e. projective coordinates, as outer > interface. In the comment, its is noted that only the affine part is > used, but can this be assured? In all circumstances? > In practice, I'm pretty confident this is the case, because both ecp_normalize_jac() and ecp_normalize_mxz() set Z to 1, these functions are always called before returning data, and if we forgot to call those functions, we'd get incorrect X and Y coordinates and fail unit test and interop tests. But as a matter of principle, I agree that exposing Jacobian coordinates in the API was a poor decision. Fortunately, we already intended to start phasing out the existing ECP interface in 3.0 (to which extend exactly is still to be discussed), and in the future is should be fully removed in favour of the PSA Crypto API, which doesn't have this problem. > 8. In my personal opinion the definition > [...] > mbedtls_ecp_keypair; > > is dangerous. Why not differentiate between private and public key > and domain parameters? I agree, and I think it's a generally accepted opinion in the crypto implementation community that private and public keys should be clearly distinguished from one another, for example by using distinct types (in typed languages). This is by the way a long-standing problem that existed in the RSA module from the start, and when ECC was added it followed a similar pattern. Again, I think the transition of the PSA Crypto API is going to be the answer here, as it will provide much cleaner key management. > 9. Regarding ECC examples: I found it very difficult that there isn't > a single example with known test vectors as in the relevant crypto > standards, i.e. FIPS 186-4 and ANSI X9.62-2005, with raw public > keys. What I mean are (defined) curves, public key value Q=(Qx,Qy) > and known signature values r and s. In the example ecdsa.c you > generate your own key pair and read/write the signature in > serialized form. In the example programs/pkey/pk_sign.c and > pk_verify.c you use a higher interface pk.h and keys in PEM format. > > So, it took me a while for a program to verify (all) known answer > tests in the standards (old standards as ANSI X9.62 1998 have more > detailed known answer tests). One needs this interface with raw > public keys for example for CAVP tests, see The FIPS 186-4 Elliptic > Curve Digital Signature Algorithm Validation System (ECDSA2VS). > > 11. In the moment, there is no single known answer tests for ECDSA > (which could be activated with #define MBEDTLS_SELF_TEST). I > wouldn't say that you need an example for every curve and hash > combination, as it is done in ECDSA2VS CAVP, but one example for > one of the NIST curves and one for Curve25519 and - if I have a > wish free - one for Brainpool would be fine. And this would solve > #9 above. > I might be misunderstanding, but isn't the function ecdsa_prim_test_vectors() in tests/suites/test_suite_ecdsa.function close to what you're looking for? I mean, except for the fact that it's not in the self-test function, and that it's using data from RFCs rather than from NIST or ANSI? But I agree this is a bit messy and could be made cleaner. Also, if you ever feel like contributing your dream self-test function for ECDSA as PR, this will be a very welcome contribution! > 13. Feature request: Since it was irrelevant for my task (only > verification, no generation) I didn't have a detailed look a your > ECC side-channel countermeasures. But obviously you use the same > protected code for scalar multiplication in verify and sign, > right? Wouldn't it be possible to use Shamir's trick in > verification with fast unprotected multi-scalar multiplication. In > the moment, mbedtls_ecdsa_verify is a factor 4-5 slower than > mbedtls_ecdsa_sign, while OpenSSLs verify is faster than sign. > Yes, this was done to save both on code size and developer time, but I agree it's suboptimal for performance. As Gilles wrote, as a general rule we tend to favour code size and security/maintainability over performance, but in that instance if we provide an option for a verify-only ECDSA build (which I agree we should), then we're likely to reach smaller code size by having a standalone unprotected implementation of multi-scalar multiplication, so that would probably be a great option: better performance _and_ smaller code. Unfortunately we're already quite busy with other things, so this kind of optimisation will probably have to wait for a bit more, but we're taking good note of the suggestion and will try to implement it in the future. Again, thanks for this comprehensive and useful feedback. Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans - move timing.c out of the library

by Torsten Schuetze

On 20/04/2020 11:51, Manuel Pegourie-Gonnard via mbed-tls wrote: > [ Context: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ ] > > Currently the crypto library includes a module called timing.c, enabled by > default in config.h (but disabled by config.py baremetal), containing various > functions related to timing (not to be confused with the time abstration > present in the platorm module). > > In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, > we're considering removing (parts of) this module from the library, and > moving its parts to a variety of other places, such as example programs (or > a library/file shared by them, like the current query_config mechanism). > > For reference, this module includes the following functions, which are used in > the following places: > > - mbedtls_timing_hardclock() implements cycle counting (on selected > architectures, not including M-class), used only in > programs/test/benchmark.c I used mbedtls_timing_hardclock() for my own benchmarking experiments on Linux and Windows, but couldn't get it to run on the target machine. So I've use my own ms counter instead. So, it could be easily removed as part of the library. Question: How do you want to do the benchmarking instead? With the same code, but outside the library? Torsten

5 years, 4 months

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3.0 plans - move net.c out of the library

by Manuel Pegourie-Gonnard

Hi all, [ Context: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ ] Currently the SSL/TLS library includes a module called net_sockets.c (formerly net.c), enabled by default in config.h (but disabled by config.py baremetal), that contains some networking functions based on POSIX or Windows sockets, including functions suitable for use as I/O callbacks with our SSL/TLS modules. Those functions are used only in example/testing programs, but nowhere in the library itself. In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, we're considering removing (parts of) this module from the library, and moving its parts to a variety of other places, such as example programs (or a library/file shared by them, like the current query_config mechanism). Reasons for removing this module from the library include: - overall the module is less portable and perhaps of lesser quality than the rest of the library - it's currently entirely untested on Windows (despite being very platform-specific) - there are often confusions about whether the module is meant to be a general-purpose networking library, or just provide basic support for our example and test, as well a simple prototypes - it's not our core area of expertise, let's do one thing and to it well Reasons for keeping (parts of) it in the library include: - having mbedtls_net_recv{,_timeout}() and mbedtls_net_send() available right in the library makes it easier to test and develop prototype - this module is listed as a component in our high-level design document [2], so perhaps removing it from the library can be seen as a bigger change? [2]: https://tls.mbed.org/high-level-design What do you think? Should we remove the entire module from the library, keep it all, or just keep some parts? In that case, which parts and where? Regards, Manuel.

5 years, 4 months

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3.0 plans - move timing.c out of the library

by Manuel Pegourie-Gonnard

[ Context: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ ] Currently the crypto library includes a module called timing.c, enabled by default in config.h (but disabled by config.py baremetal), containing various functions related to timing (not to be confused with the time abstration present in the platorm module). In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, we're considering removing (parts of) this module from the library, and moving its parts to a variety of other places, such as example programs (or a library/file shared by them, like the current query_config mechanism). For reference, this module includes the following functions, which are used in the following places: - mbedtls_timing_hardclock() implements cycle counting (on selected architectures, not including M-class), used only in programs/test/benchmark.c - mbedtls_timing_get_timer() is a millisecond counter (only for Unix and Windows), used only in programs/test/udp_proxy.c - mbedtls_set_alarm() is an abstraction of alarm() (only for Unix and Windows), used only in programs/test/benchmark.c - mbedtls_timing_set_delay() and mbedtls_timing_get_delay() are an example implementation (only for Unix and Windows) of timer callbacks for DTLS, only used in programs/ssl/*.c Reasons for removing this module from the library include: - overall the module is less portable and of lesser quality than the rest of the library - it's also very hard to test and we've lost a lot of time and energy to that, with very limited success - it doesn't really belong in libmbedcrypto - it's not our core area of expertise, let's do one thing and to it well Reasons for keeping (parts of) it in the library include: - for mbedtls_timing_set_delay() and mbedtls_timing_get_delay(): they're convenient to have for DTLS examples and prototyping, we could keep them in some place in libmbedtls (not libmbedcrypto). What do you think? Should we remove the entire module from the library, or keep some parts? In that case, which parts and where should they live? Regards, Manuel.

5 years, 4 months

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3.0 plans - move certs.c out of the library

by Manuel Pegourie-Gonnard

Hi all, In this new installment of "let's discuss ideas for Mbed TLS 3.0" [1]: should we move certs.c out of the library? [1]: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ Currently the X.509 library includes test certificates and keys, which are enabled by default in config.h - `MBEDTLS_CERTS_C`. These are used in the following places: - in library/x509.c in mbedtls_x509_self_test() - in tests/suites/test_suite_ssl.function - in programs/fuzz and programs/ssl In Mbed TLS 3.0, as part of our effort to clean up and minimize our API, we'd like to remove certs.h and the certificates it contains from the library (except perhaps one static cert for mbedtls_x509_self_test()). Tests and example programs that need built-in certificates could still get them using any mechanism, included a file certs.c similar to the current one - but this file would no longer live in library or be included when building libmbedx509. Reasons include: - Including test certificates and keys in the library provides little value, as users will want to use their own certificates and keys anyway. - Shipping private keys as part of the library is bad practice, even under the `mbedtls_test_` sub-namespace. There's a slight risk that some users could use them for prototyping and then inadvertently keep using unsafe private keys in production. If you disagree or have concerns, please speak up! Also, if want to suggest ideas for where the replacement to library/certs.c should live or how it could be maintained, now's a good time as well! Regards, Manuel.

5 years, 4 months

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Session resumption + PSKs in Mbed TLS 3.X

by Hanno Becker

Hi all, I would like to bring up the following: (How) Shall the APIs for PSKs and TLS session resumption be modified in Mbed TLS 3.0? The motivation for this question is the consolidation of PSKs, ticket-based resumption and session-id-based resumption in TLS 1.3. Now, while there will be no TLS 1.3 support in Mbed TLS 3.0 as it stands, I think it would be beneficial to make the API amenable to TLS 1.3 as much as possible already now. Finding the right API here is non-trivial, and I'll describe first how the current API works and how TLS 1.2 and 1.3 differ, before making suggestions on how the Mbed TLS 3 API might look like. The mail is therefore quite long, but I hope you'll bear with me. # Session Resumption in Mbed TLS 2.X Recall how resumption works in Mbed TLS 2.X on the client: 1. Establish a connection as usual 2. Store established session for later re-use `mbedtls_ssl_session_save()` saves connection parameters relevant for session resumption in an instance of `mbedtls_ssl_session`. Optional: 2.1: Serialize session for offline storage 2.2: Deserialize session 3. Loading a stored session `mbedtls_ssl_session_load()` is called on the stored session after initialization and before running the handshake via `mbedtls_ssl_handshake()`. 4. Connect using stored session Run `mbedtls_ssl_handshake()` as usual. To my knowledge, the following is transparent to the user: * The means by which resumption is achieved, which can be either id- or ticket-based. * Whether the session was resumed or not - there is a silent fallback to a full handshake when session resumption is rejected by the server. On the server, ticket- and id-based resumption are configured independently as follows: - ID-based resumption is controlled via `mbedtls_ssl_conf_session_cache()` - Ticket-based resumption is controlled via `mbedtls_ssl_conf_session_tickets_cb()`. # PSKs in Mbed TLS 2.X Coming to PSKs: First, recall that, under the hood, resumed connections establish a master secret purely on the basis of a previous master secret, without resorting to asymmetric crypto. The same is true for PSK-based connections, and this observation is embodied in TLS 1.3 which, as mentioned, consolidates resumption and PSKs. In TLS 1.2, though, PSKs and session resumption are different, and consequently Mbed TLS handles them through a separate API `mbedtls_ssl_conf_psk()`, which takes the PSK identifier and the PSK itself. Side-question: Should this apply to the SSL configuration or the SSL context? It seems to me that somebody might want to run multiple PSK-based connections with different PSKs, but same configuration otherwise. At the moment, this would require a configuration per connection. Maybe this decision of what belongs at the level of the config could be thoroughly discussed independently? # PSKs in TLS 1.3 In TLS 1.3, all kinds of resumptions are hanlded ander the umbrella of PSKs: The client offers PSK identities in its ClientHello, the server picks one or leaves it, and the master secret for the connection is derived from the PSK associated with the PSK identity. Underlying this is some form of translation `PSK-Identity -> PSK` on the server which allows to derive the PSK from the PSK identity. How this mapping is realized is entirely implementation-specific, but it can take at least the following forms, giving back all forms of session resumption: - 'PSK Identity -> PSK' via database lookup: This subsumes classical PSKs and ID-based resumption, since the data necessary to resume a session is stored on the server. - 'PSK Identity -> PSK' via AEAD: The PSK can be encoded in the PSK identity itself by using some authenticated encryption of the PSK as the PSK identity, the key for which resides on the server. This subsumes Ticket-based resumption. There are the following noteworthy differences, though: 1. In TLS 1.2, the server provides a 'PSK identity hint' and the client picks a particular PSK identity. In TLS 1.3, the client offers a _list_ of PSKs, and the server picks one or none. 2. In TLS 1.2, the server can issue only a single session ticket. In TLS 1.3, the server can issue as many session tickets as he wishes, and the client can use any of those for later session resumption. This has the following consequences for the API: 1. The PSK-configuration API must allow the configuration of multiple PSKs on the client. 2. There must be a means to export more than one session ticket for later resumption. # API considerations for Mbed TLS 3.X ## Part 1: Load/Save API In essence, keep the flow of `mbedtls_ssl_session_load/save()`, but make the following adjustments. Whether the target structure remains `mbedtls_ssl_session` and how it looks like internally isn't relevant at this point and is up to discussion. 1. It must be possible 'save' a session multiple times, which in TLS 1.3 amounts to exporting the tickets issued by the server one-by-one. This can be realized in a variety of ways, for example: - Allow calling `mbedtls_ssl_session_save()` multiple times, and modify its semantics from the idempotent nature of Mbed TLS 2.X to iterating through the available tickets, and returning an error when no more tickets are available. This has the benefit that it likely requires no code change for users migrating from Mbed TLS 2.X, since a change is needed only when an application stores a single session multiple times, which could be done by calling `mbedtls_ssl_session_save()` multiple times before, while now one would need to call it once and manually replicate the obtained session structure. On the negative side, this wastes memory for applications not interested in session resumption, or those that only need a single ticket. We don't want the server to be able to flood the client with arbitrarily many tickets. - Allow registering a callback that's triggered whenever a new ticket arrives. The drawback of this is that it is larger deviation from the Mbed TLS 2.X API. On the positive side, applications that don't need tickets, or only need a limited number of such, can simply drop further tickets and thereby prevent allocating RAM for them. 2. It must be possible to 'load' multiple sessions, meaning that the client should offer any of them to the server for resumption. ## Part 2: Consolidation with PSK Make it possible to setup an `mbedtls_ssl_session` (or whatever it will be called) structure manually from an externally PSK provisioned PSK, and allow loading this session for resumption as above, via one of potentially many calls to `mbedtls_ssl_session_load()`. There are multiple variants to this, for example: 1. Make `mbedtls_ssl_session` transparent so users can build it manually by filling the respective fields. 2. Provide a helper API to build a session from a PSK. The old API `mbedtls_ssl_conf_psk()` can then be _derived_ from this for convenience, building a session from the provided PSK and loading it, in a single API. Before going into further details and making the mail even longer: What do you think of this approach? Do you see alternatives? Best, Hanno IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] Some thoughts towards mbed TLS 3.0

by Gilles Peskine

Wow! First, thanks for this extensive feedback! That's very helpful, and appreciated. I'm going to reply to a few points. On a general note, you can see headlines for the main topics we're currently planning to work on in the Mbed TLS roadmap at https://developer.trustedfirmware.org/w/mbed-tls/roadmap/ . Please note that everything I write is based on current plans, which may change through the TrustedFirmware planning process or if real life shows that a current plan is not doable. Over time, we're transitioning the API for the crypto part of the library from the current mbedtls_xxx functions to psa_xxx, which have a somewhat different philosophy: less exposure of internals, more protection against misuse, no reliance on malloc. Mbed TLS 3.0 will start the transition. On 14/04/2020 21:10, Torsten Schuetze via mbed-tls wrote 1. I really missed an Initialize, Update, Finalize (IUF) interface for CCM. For GCM, we have mbedtls_gcm_init(), mbedtls_gcm_setkey(), mbedtls_gcm_starts(), mbedtls_gcm_update() iterated, mbedtls_gcm_finish(), mbedtls_gcm_free() or the comfort functions mbedtls_gcm_crypt_and_tag() and mbedtls_gcm_auth_decrypt(). For CCM, only mbedtls_ccm_init(), mbedtls_ccm_setkey(), mbedtls_ccm_encrypt_and_tag() or mbedtls_ccm_auth_decrypt() and mbedtls_ccm_free(). With this interface it was only possible to encrypt and tag 128 kByte on my target system, while with GCM I could encrypt much larger files. see Github issue #662 and my comment there In Mbed TLS 3.0, mbedtls_ccm_xxx() will not be a public interface anymore. We are planning to add support for multipart CCM in the psa_aead_xxx() interface (the prototypes are already in psa/crypto.h but their implementation is planned for some time in the next few months). We are not currently planning to add support for multipart CCM through mbedtls_cipher_xxx(), which in Mbed TLS 3 will be legacy functions. However, we would probably accept such support if it was contributed externally. 2. The next step, of course, is to integrate this into the higher mbedtls_cipher layer. Regarding higher, abstract layers: I often didn't understand which interface I was supposed to use. In general, I like to use the lowest available interface, for example, #include "mbedtls/sha512.h" when I want to use sha512. However, if I need HMAC-SHA-512 or HKDF-HMAC-SHA-512 then I have to use the interface in md.h. For hash functions this is fine. Almost all hash functions are supported via md.h. (I missed SHA-512/256 which is sometimes preferable to SHA-256 on 64bit systems). But with cipher.h, I can only access Chacha20Poly1305 and AES-GCM, not AES-CCM. In Mbed TLS 3, there will generally be a single public layer. Exposing lower layers helps with code size on resource-constrained devices, but it also has downsides, including locking down the APIs. 4. That I couldn't configure AES-256 only, i.e. without AES-128 and AES-192, was to be expected (and the code overhead is not that much). But in modern modes of operations nobody needs AES decryption, only the forward direction. Sometimes modern publications as Schwabe/Stoffelen "All the AES you need on Cortex-M3 and M4" provide only the forward direction. So, it would be fine if one could configure an AES (ECB) encryption only without decryption. Of course, this is only possible if we don't use CBC mode, etc. This wouldn't only save the AES decryption code but also the rather large T-tables for decryption. For information, there is a branch of Mbed TLS called "baremetal", forked from Mbed TLS 2.16, which you can find on GitHub: https://github.com/ARMmbed/mbedtls/blob/baremetal . This branch is optimized for small code size, sometimes at the expense of speed and often at the expense of features. It has build options MBEDTLS_AES_ONLY_ENCRYPT and MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH. However I would not recommend using it in production because Arm (who still maintain this branch even after Mbed TLS itself has moved to TrustedFirmware) does not make any promise of stability. A feature that you rely on may be removed without notice. I mention this branch because eventually, we do plan to port the improvements that don't sacrifice features to the Mbed TLS development branch. I can't give a timeline for this however. With the current Mbed TLS, if you don't use CBC, I think you can save some code in aes.o by defining MBEDTLS_AES_DECRYPT_ALT and MBEDTLS_AES_SETKEY_DEC_ALT and providing functions mbedtls_aes_setkey_dec() and mbedtls_internal_aes_decrypt() that do nothing. 5. Regarding AES or better the AES context-type definition [snip] 6. In general, the contexts of mbedTLS are rather full of implementation specific details. Most extreme is mbedtls_ecp_group in ecp.h. Wouldn't it be clearer if one separates the standard things (domain parameters in this case) from implementation specific details? As a general design principle, context types in Mbed TLS 3 will be opaque. This will let us, for example, redesign mbedtls_aes_context and mbedtls_cipher_context. 9. Regarding ECC examples: I found it very difficult that there isn't a single example with known test vectors as in the relevant crypto standards, i.e. FIPS 186-4 and ANSI X9.62-2005, with raw public keys. What I mean are (defined) curves, public key value Q=(Qx,Qy) and known signature values r and s. In the example ecdsa.c you generate your own key pair and read/write the signature in serialized form. In the example programs/pkey/pk_sign.c and pk_verify.c you use a higher interface pk.h and keys in PEM format. So, it took me a while for a program to verify (all) known answer tests in the standards (old standards as ANSI X9.62 1998 have more detailed known answer tests). One needs this interface with raw public keys for example for CAVP tests, see The FIPS 186-4 Elliptic Curve Digital Signature Algorithm Validation System (ECDSA2VS). 11. In the moment, there is no single known answer tests for ECDSA (which could be activated with #define MBEDTLS_SELF_TEST). I wouldn't say that you need an example for every curve and hash combination, as it is done in ECDSA2VS CAVP, but one example for one of the NIST curves and one for Curve25519 and - if I have a wish free - one for Brainpool would be fine. And this would solve #9 above. I don't get the point here. ECDSA is randomized, so you can't have a known answer test. The test suite does have known answer tests for deterministic ECDSA. 10. While debugging mbedtls_ecdsa_verify() in my example program, I found out, that the ECDSA, ECC and MPI operations are very, let's say, nested. So, IMHO there is a lot of function call overhead and special cases. It would be interesting to see what's the performance impact of a clean, straight-forward mbedtls_ecdsa_verify without restartable code, etc. to the current one. As far as I remember, the refactoring done to add the restartable code had no measurable impact on performance. What does have a significant impact on performance is that the bignum module uses malloc all the time. We would like to completely rewrite bignum operations at some point during the 3.x series, not only for performance but also because its design makes it hard not to leak information through side channels. 12. Just a minor issue: I only needed ECDSA signature verification, therefore I only included MBEDTLS_ASN1_PARSE_C. But it is not possible to compile without MBEDTLS_ASN1_WRITE_C needed for ECDSA signature generation. I'm not sure if I've written it down anywhere, but I'd like to remove the dependency of ECDSA on ASN1 altogether. Parsing and writing a SEQUENCE of two INTEGERs can be done with ad hoc code. Likewise for what little ASN1 the RSA module uses. And then asn1*.o can move out of libmbedcrypto and libpsacrypto, and into libmbedx509 where it belongs. Having only signature verification would be useful, indeed. That may happen with the bignum rewrite I mentioned above, if signature verification ends up using some faster non-constant-time code (this is also relevant for #13). 14. Design question: In the moment, both GCM and CCM use their own implementation of CTR encryption which is very simple. But then we have mbedtls_aes_crypt_ctr() in aes.h which is very simple, too. Let's assume at one day we have a performance optimized CTR encryption (for example from Schwabe & Stoffelen) with all fancy stuff like counter-mode caching etc. Then this would have to be replaced at three places at minimum. While isn't the code at this point more modularized? Is this a dedicated design decision? Having a single implementation of CTR is on the PSA roadmap because if there's a hardware accelerator that does it, we want to use it everywhere it's relevant. In Mbed TLS (or more precisely in its ancestor PolarSSL, if not _its_ ancestor XySSL), there was a conscious design decision to make each .c file as independent from the others as possible, which explains why camellia_ctr is completely independent from aes_ctr. But I don't know why ccm and gcm reimplement ctr. Why do I find at so many places for( i = 0; i < 16; i++ ) y[i] ^= b[i]; instead of a fast 128-bit XOR macro with 32bit aligned data? As a programmer who doesn't write compilers, I think this is the right way to xor 16 bytes, and it's the compiler's job to optimize it to word or vector operations if possible. Admittedly this does mean the compiler has to know that the data is well-aligned, which can be hard to guarantee and easy to forget. So, that's it for the moment. I hope I could give some hints for the further development of mbedTLS. Feel free to discuss any of the above points. It's clear to me that we cannot have both: clear and simple to understand code and performance records. Right. Also maintainable code and minimal code size, because minimal code size comes from letting the application developer #ifdef out everything that they don't care about, but this is a nightmare to test. It's one of the topics we're thinking about for Mbed TLS 3 and beyond. In general, Mbed TLS is primarily targeted at embedded systems, and is likely to privilege 1. security (including side channel resistance) and 2. code size. This doesn't mean that we don't care about performance, just that it isn't our top priority. That being said, we also do have some code that's optimized for performance (without compromising security) and not code size: the library already includes X25519 from Project Everest (https://project-everest.github.io/) (turn it on with MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED). This is code that's formally proven not only for functional correctness, but also for side channel resistance; the implementation has aggressive inlining which makes it very fast, but obviously also large in terms of code size. Hopefully other algorithms will follow soon. Ciao, Torsten Once again, thanks for the detailed feedback, and I hope we can improve Mbed TLS for everyone! -- Gilles Peskine Mbed TLS developer IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code base

by Gilles Peskine

>From the perspective of an application developer whose platform doesn't have a native malloc, the advantage for Mbed TLS to include its own malloc is one less dependency to integrate (so one less source of potential incompatibilities, one less component to integrate into the build, one less set of parameters to configure, one less feed of security updates to keep up with, etc.). I expect that choosing the Mbed TLS allocator would give poorer performance and higher RAM consumption than choosing the best allocator that exists out there. But it gives better time to market, and potentially a better security posture (the highest-performance allocator may or may not turn out to be actively maintained). -- Gilles Peskine Mbed TLS developer On 16/04/2020 14:19, Janos Follath via mbed-tls wrote: > Hi, > > Thank you for sharing your view, it makes perfect sense. > > You mention that you would consider keeping the module internally for the sake of baremetal applications. How would this serve the user better than choosing a third party malloc implementation? (Assuming that there are better implementation out there than ours, which I haven't confirmed, but it is not hard to imagine that such exists.) > > Regards, > Janos > > > On 15/04/2020, 21:11, "mbed-tls on behalf of Gilles Peskine via mbed-tls" <mbed-tls-bounces(a)lists.trustedfirmware.org on behalf of mbed-tls(a)lists.trustedfirmware.org> wrote: > > On 09/04/2020 13:17, Janos Follath via mbed-tls wrote: > > Hi, > > > > Based on what I read on this thread it seems an accepted point of view that the toolchain provided C standard library implementations are less trusted than the toolchains themselves. Can somebody please help me understand the reasoning behind this distinction? > > Well, I disagree with this statement. I trust the toolchain to implement > the C standard library correctly, and with good performance for the > target platform. I do not want to provide my own implementation of > standard functions. > > I only trust the toolchain to be functionally correct. I don't know > about its security. I certainly can't rely on the toolchain to have > security characteristics that are not guaranteed by the language > definition. For example, I do trust memset_s() to zero out sensitive > memory if the toolchain provides it, but I don't trust memset() for this > task. > > On the topic at hand, my personal opinion of memory_buffer_alloc is that > it doesn't belong in Mbed TLS. I hope that when PSA crypto is a > standalone product, it won't use malloc internally, and so it certainly > won't provide a malloc implementation. I wouldn't necessarily say the > same thing of Mbed TLS 4.0: it's difficult to design an X.509 interface > that doesn't use malloc. But if we can do it, I think we should. > > I recognize that there are many bare-metal applications that don't use > malloc themselves, but use Mbed TLS. For their sake, it does make some > sense for Mbed TLS to have its own malloc implementation. But the focus > is for internal use, not on serving as a general-purpose allocator for > applications that also use malloc for non-mbedtls-related purposes. > > -- > Gilles Peskine > Mbed TLS developer > > > IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. > -- > mbed-tls mailing list > mbed-tls(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls > > IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans: remove memory_buffer_alloc.c from the code base

by Janos Follath

Hi, Thank you for sharing your view, it makes perfect sense. You mention that you would consider keeping the module internally for the sake of baremetal applications. How would this serve the user better than choosing a third party malloc implementation? (Assuming that there are better implementation out there than ours, which I haven't confirmed, but it is not hard to imagine that such exists.) Regards, Janos On 15/04/2020, 21:11, "mbed-tls on behalf of Gilles Peskine via mbed-tls" <mbed-tls-bounces(a)lists.trustedfirmware.org on behalf of mbed-tls(a)lists.trustedfirmware.org> wrote: On 09/04/2020 13:17, Janos Follath via mbed-tls wrote: > Hi, > > Based on what I read on this thread it seems an accepted point of view that the toolchain provided C standard library implementations are less trusted than the toolchains themselves. Can somebody please help me understand the reasoning behind this distinction? Well, I disagree with this statement. I trust the toolchain to implement the C standard library correctly, and with good performance for the target platform. I do not want to provide my own implementation of standard functions. I only trust the toolchain to be functionally correct. I don't know about its security. I certainly can't rely on the toolchain to have security characteristics that are not guaranteed by the language definition. For example, I do trust memset_s() to zero out sensitive memory if the toolchain provides it, but I don't trust memset() for this task. On the topic at hand, my personal opinion of memory_buffer_alloc is that it doesn't belong in Mbed TLS. I hope that when PSA crypto is a standalone product, it won't use malloc internally, and so it certainly won't provide a malloc implementation. I wouldn't necessarily say the same thing of Mbed TLS 4.0: it's difficult to design an X.509 interface that doesn't use malloc. But if we can do it, I think we should. I recognize that there are many bare-metal applications that don't use malloc themselves, but use Mbed TLS. For their sake, it does make some sense for Mbed TLS to have its own malloc implementation. But the focus is for internal use, not on serving as a general-purpose allocator for applications that also use malloc for non-mbedtls-related purposes. -- Gilles Peskine Mbed TLS developer IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. -- mbed-tls mailing list mbed-tls(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls

5 years, 4 months

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Re: [mbed-tls] 3.0 plans: remove pkcs11.c from the code base

by Manuel Pegourie-Gonnard

Hi Gilles, Thanks for this precision, as well as the reminder of the existing github issue. With no opposition here in a week, and none on github for nearly 3 months either, plus no opposition when we marked it as deprecated in 2.21 in February, I'm also moving this to the "Accepted" section on the wiki discussion tracking page: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ - but again, it's still time to voice concerns until we've actually removed it from the code base. Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans: remove havege.c from the code base

by Manuel Pegourie-Gonnard

Hi Gilles, Thanks for your feedback and for providing a link to the existing issue, which I completely forgot about - I'll reference that in the wiki as well. Since it's been a week, with one agreement and no opposition, I'm also moving this to the "Accepted" section in the summary wiki page: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ - though again, it you have concerns it's still time to voice them. Regards, Manuel.

5 years, 4 months

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Re: [mbed-tls] 3.0 plans: remove old TLS options from the code base entirely

by Manuel Pegourie-Gonnard

Hi all, Since this list of old options was probably not controversial in the first place and there has been no opposition in more than a week (a time that was sufficient for other thread in the same series to get several reactions), I'm moving this from "Under discussion" to "Accepted" in the summary wiki page: https://developer.trustedfirmware.org/w/mbed-tls/tech-plans-3.0/ This is not meant to shut down discussion and if you disagree or have concerns it's still time to voice them - this is just to simplify tracking of the discussions. Best regards, Manuel.

5 years, 4 months

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