- mbed-tls - lists.trustedfirmware.org

Re: [mbed-tls] Support for ECDH key generation with Curve25519

by Gilles Peskine

Hi Brian, It's not clear to me what you're trying to do. Mbed TLS supports Curve25519 arithmetic for X25519, accessible through the mbedtls_ecdh_xxx interface. If you want to use Curve25519 for some other purpose, this may or may not be supported via direct access to the mbedtls_ecp_xxx interface. The curve arithmetic code only supports predefined groups, it does not support changing the generator without patching the library. For Curve25519, the generator is the point (X,Z)=(9,1). Isn't this the generator you want? Best regards, -- Gilles Peskine Mbed TLS developer On 30/04/2021 17:39, Brian via mbed-tls wrote: > Hi all, > I'm trying to set the generator g to a value of 9 for the Curve25519 with mbedtls_ecp_gen_key function. However I cannot find any way to accomplish that. > Could anyone help me? > Thank you, have a nice day,Brian

5 years, 3 months

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URGENT PLEASE

by Younes Boulahya

<mbed-tls(a)lists.trustedfirmware.org>I am using STM32F303RCT6 and W5500, I want to upgrade to HTTPS and SFTP, but I can't find any working example that I can use, can you provide me a simple one PLEASE, of both HTTPS and SFTP. I attach my current c code, thank you so much 🌷

5 years, 3 months

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Support for ECDH key generation with Curve25519

by brian_d＠tutanota.com

Hi all, I'm trying to set the generator g to a value of 9 for the Curve25519 with mbedtls_ecp_gen_key function. However I cannot find any way to accomplish that. Could anyone help me? Thank you, have a nice day,Brian

5 years, 3 months

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Problems during certificate verifing

by stefano664

Good morning, I'm testing a routine that verify the validity of an intermediate certificate, against my root certificate. Both certificates are generated on my machine. The code to do this is here: https://wtools.io/paste-code/b4OL I can do the verify with openSSL and works fine. When I pass certificates tombedTLS it returns these errors: The certificate is signed with an unacceptable hash. The certificate is signed with an unacceptable PK alg (eg RSA vs ECDSA). The certificate is signed with an unacceptable key (eg bad curve, RSA too short). Can someone help me to find the mistakes? Thanks for your help. ROOT CERTIFICATE: -----BEGIN CERTIFICATE----- MIIB8TCCAXagAwIBAgIBATAMBggqhkjOPQQDAgUAMDkxCzAJBgNVBAMMAkNBMR0w GwYDVQQKDBRDb21lbGl0IEdyb3VwIFMucC5BLjELMAkGA1UEBhMCSVQwHhcNMDEw MTAxMDAwMDAwWhcNMzAxMjMxMjM1OTU5WjA5MQswCQYDVQQDDAJDQTEdMBsGA1UE CgwUQ29tZWxpdCBHcm91cCBTLnAuQS4xCzAJBgNVBAYTAklUMHYwEAYHKoZIzj0C AQYFK4EEACIDYgAE/u9D/9E9S8kmJ5W75GwaZxUuXYuCYfszCsjNEuylVMj8N1r6 Ce+FJ3eSKQGgh2/H2Pd5Ck7TENQSuVBZIVsUcUv5q/MGGJWUNLCSZm2b5kadVKXQ 6Cn6t7RDFQ0IvRoLo1AwTjAMBgNVHRMEBTADAQH/MB8GA1UdIwQYMBaAFOzrPv2f Rkotop0JzDEg/9CtjcRjMB0GA1UdDgQWBBTs6z79n0ZKLaKdCcwxIP/QrY3EYzAM BggqhkjOPQQDAgUAA2cAMGQCMAxEjQOUP2hC3yhGIkz04Y9fFR6WWH8kUqQEutfb 57Q9ADRFsmAVtJgOZEsVhnZ6ugIwcRK7dngvNozV9Uu4ifhDCLF7qQhAH4XyQ/WI GgKtCIBIps/H+JQNqjpwsVs8zlER -----END CERTIFICATE----- INTERMEDIATE CERTIFICATE: -----BEGIN CERTIFICATE----- MIIDDDCCAo+gAwIBAgIBATAMBggqhkjOPQQDAgUAMDkxCzAJBgNVBAMMAkNBMR0w GwYDVQQKDBRDb21lbGl0IEdyb3VwIFMucC5BLjELMAkGA1UEBhMCSVQwHhcNMDEw MTAxMDAwMDAwWhcNMzAxMjMxMjM1OTU5WjCBozE+MDwGA1UEAww1Q29tZWxpdCBD bG91ZCBBcyBEZXYgS2ZHWUFjWHg5U3NvMnlic3plcDRQTjZjR295R1BMaTAxJjAk BgNVBAsMHUNvbWVsaXQgR3JvdXAgU3BhIC0gQ2xvdWQgTGFiMRowGAYDVQQKDBFD b21lbGl0IEdyb3VwIFNwYTEQMA4GA1UECAwHQmVyZ2FtbzELMAkGA1UEBhMCSVQw ggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCfGrKbFRgC5o8REbcYdRzW FXS772+CC15nXCJR67gWL1wmKzrCekkFNlOnQrsPhe4iYnkhLuBYNWaVvSaHt9dS X/ZBbJ3bRnGAarw7QnirLZJFYSRRBhMw6xi91nt8kIvcA6kACFcooaRmg/jQzCyb eXO1skJhDv13TxwDB8UTtRkfOTFl23FekMPWmJpqU1YxjAAYRtcY4jGAtV4D7T3V 3WjZ0eaIjl9n2g9/slG6p3ZSjONIRmyTiBRQNynKCxy1Q9Px1ohDCcS2SsK0smy6 0EzCghEz8QjAWs7U9Ilh3OTCdCpV9clp1DQrjbDZky1rMEd7mRmTp8Fmd2c3ld0F AgMBAAGjUDBOMB0GA1UdDgQWBBT3OOc7ZPbeOBTkeYPBFQcQTLhECDAfBgNVHSME GDAWgBTs6z79n0ZKLaKdCcwxIP/QrY3EYzAMBgNVHRMEBTADAQH/MAwGCCqGSM49 BAMCBQADaQAwZgIxAJvrL0kIeB4mvRJT1MRA0Kc/mw5ZVVv0ErOQqLhQShECw6+K s5DL9V/tHf72iCCivAIxANfBJ2IMLzSZCOrSmr9fOCQktM6mFC5PyAuZX+3OGPfU UuJwph7GaoWW+fw1IxQm2Q== -----END CERTIFICATE----- Thanks a lot, Stefano

5 years, 3 months

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Mbed TLS 3.0 branch transition

by Dave Rodgman

Hi, Today we are switching our branches around, so that the development branch focuses on Mbed TLS 3.0, to be released mid-year. This will include API-breaking changes. 2.x development work will continue on the development_2.x branch. After merging development_3.0 onto development, the development_3.0 branch will be removed. There is no change to the process for submitting PRs: new PRs should continue to target development, with backports to 2.x and 2.16 as needed. (The exception would be a bug-fix that only affects older branches, which would only need ports to the affected branches and not to development). As part of the 3.0 work, we are looking at various things that can be removed from the library. For some of these, we’ve notified the mailing list – please let us know in the next week if you have a good reason for retaining the feature in question. - Remove support for TLS 1.0, TLS 1.1 and DTLS 1.0 https://github.com/ARMmbed/mbedtls/issues/4286 - Remove support for the "Truncated HMAC" (D)TLS extension https://github.com/ARMmbed/mbedtls/issues/4341 - Remove support for 3DES ciphersuites in (D)TLS https://github.com/ARMmbed/mbedtls/issues/4367 - Remove support for RC4, Blowfish, XTEA, MD2 and MD4 https://github.com/ARMmbed/mbedtls/issues/4084 - Remove support for pre-v3 X.509 certificates with extensions https://github.com/ARMmbed/mbedtls/issues/4386 - Remove the RSA key mutex https://github.com/ARMmbed/mbedtls/issues/4124 - Remove MBEDTLS_CHECK_PARAMS https://github.com/ARMmbed/mbedtls/issues/4313 - 3.0 and 2.x :- Minimum development environment: is it OK to require Python >= 3.6 and/or CMake >= 3.5.2? https://lists.trustedfirmware.org/pipermail/mbed-tls/2021-March/000319.html Dave Rodgman

5 years, 3 months

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Removal of generated source and build files from the development branch

by Gilles Peskine

Hello, A number of files in the Mbed TLS source tree are automatically generated from other files, with a content that does not depend on the platform or configuration. We are considering removing the generated files from the development branch in Git, at least during the work towards Mbed TLS 3.0. This would affect at least the development branch until the 3.0 release, and may affect the development_2.x branch and the development branch after the 3.0 release. Long-time support branches and official releases will continue to have these source files in the Git tree. The reason to remove the generated files is to facilitate development, especially with the restructuring that is happening as we prepare a new major version of the library. This is an experimental change; depending on how effective it is, we may or may not wish to restore the generated files on the development branch when 3.0 stabilizes. It's also still possible that we will not go ahead with this change, depending on the impact on our CI and on the feedback we receive. The affected files are: * Two library source files: library/error.c and library/version_features.c. * Parts of some test programs: programs/test/query_config.c and programs/psa/psa_constant_names_generated.c. * The Visual Studio project files. * Some unit test data files. What does this change for you? **If you were using a long-time support branch or an official release**: no change. **If you were using the supplied GNU Makefile**: there should be no effective change. **If you were using CMake, Visual Studio or custom build scripts** on the development branch: Perl (>=5.8) will be required to generate some library sources and to generate the Visual Studio project files. Python (>=3.4) was already required to run config.py and to build the unit tests. Note that the generated files are independent of the Mbed TLS configuration, so if your deployment has a pre-configuration step, you can generate the files at this step: no new tool is required after the library is configured. The ongoing work (not complete yet as I write) is at https://github.com/ARMmbed/mbedtls/pull/4395 if you want to see what this change means concretely. We are aware that the additional dependencies are a burden in some environments, which is why we will definitely not change anything to releases or to current and future long-time support branches. If you are building Mbed TLS from the development branch and this change affects you, please let us know what constraints apply to your environment. Best regards, -- Gilles Peskine Mbed TLS developer

5 years, 3 months

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Re: [mbed-tls] Uninitialized variable in rsa_prepare_blinding

by Gilles Peskine

Hello, The macro MBEDTLS_MPI_CHK sets ret, so this particular case is safe. That being said, we do have a hygiene rule to initialize ret variables, to avoid accidentally having uninitialized variables in edge cases. I'll file an issue to fix those. Thanks for reaching out! -- Gilles Peskine Mbed TLS developer On 21/04/2021 17:33, momo 19 via mbed-tls wrote: > Hello, > > I would like to report a possible bug in rsa_prepare_blinding function > in rsa.c > (https://github.com/ARMmbed/mbedtls/blob/v2.26.0/library/rsa.c > <https://github.com/ARMmbed/mbedtls/blob/v2.26.0/library/rsa.c>). I am > not sure if it is a real issue, but I think that there is a > possibility to use uninitialized variable ret: > > static int rsa_prepare_blinding( mbedtls_rsa_context *ctx, > int (*f_rng)(void *, unsigned char *, size_t), void > *p_rng ) > { > int ret, count = 0; <--- uninitialized variable ret > mbedtls_mpi R; > > mbedtls_mpi_init( &R ); > > if( ctx->Vf.p != NULL ) > { > /* We already have blinding values, just update them by > squaring */ > MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, > &ctx->Vi ) ); > MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, > &ctx->N ) ); > MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, > &ctx->Vf ) ); > MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, > &ctx->N ) ); > > goto cleanup; <--- going to cleanup without setting a value of ret > } > > (Skipping lines for readability) > > cleanup: > mbedtls_mpi_free( &R ); > > return( ret ); <--- returning uninitialized variable ret > } > > Best regards, > grapix121 > >

5 years, 3 months

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Uninitialized variable in rsa_prepare_blinding

by momo 19

Hello, I would like to report a possible bug in rsa_prepare_blinding function in rsa.c (https://github.com/ARMmbed/mbedtls/blob/v2.26.0/library/rsa.c). I am not sure if it is a real issue, but I think that there is a possibility to use uninitialized variable ret: static int rsa_prepare_blinding( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret, count = 0; <--- uninitialized variable ret mbedtls_mpi R; mbedtls_mpi_init( &R ); if( ctx->Vf.p != NULL ) { /* We already have blinding values, just update them by squaring */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) ); goto cleanup; <--- going to cleanup without setting a value of ret } (Skipping lines for readability) cleanup: mbedtls_mpi_free( &R ); return( ret ); <--- returning uninitialized variable ret } Best regards, grapix121

5 years, 3 months

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Re: [mbed-tls] Signing messages with ECDSA

by stefano664

Excuse me, I replied to your e-mail without note that I'm replying to your address instead of mailing-list address. Now I'll do some other tests, starting from a blank project. I can't send a fully compilable FW because my target is an ESP32 with an OPTIGA crypto chip connected,. than it is necessary to have my hardware to run it. But attached I put my mbedtls configuration. Thank you, Stefano Il giorno mer 21 apr 2021 alle ore 14:36 Gilles Peskine < gilles.peskine(a)arm.com> ha scritto: > I adjusted your code to compile and added the missing definitions and > declarations, and this version works for me. I've attached my code. Here's > the output I get (Mbed TLS , default configuration): > > Message: PLUTOxPLUTOxPLUTOxPLUTOxPLUTOxxx > Private key: -----BEGIN EC PRIVATE KEY----- > MIGkAgEBBDCv5Vq0yRsOKLkkaI0lR32vByL9MB+4O0f+bhVErb8Fd0W1XFhN1897 > iAtnV/DeXDygBwYFK4EEACKhZANiAARgYE9uzG+nXYDoydWyDE6wrlgxiRKqm6kg > si00tFa0KD//vCemOAoYAmmbtFd9RvE6tNOw+Ze5eRtVvosmvYl5IoWx4Jda+Wv9 > ftRXkUk3nRzcAmXnG7bGmgwNC2iC73s= > -----END EC PRIVATE KEY----- > > Hash: yrmtrgMb4WzvHD5XWwb00yAE13RCi934x2ySjcWup5g= > Signature: MGQCMD8pezXqUF6v01b0WQiIUZWuuvxPR1tT15YnN9atogKR2pBPizBYbbhjAIz+ftm78AIwDogKWZVxDk5r6I38oIn0JALO7h8EcTCwjUsulYS5BRl8iyITAC42Xx+HlRPofwbr > Public key: -----BEGIN PUBLIC KEY----- > MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEYGBPbsxvp12A6MnVsgxOsK5YMYkSqpup > ILItNLRWtCg//7wnpjgKGAJpm7RXfUbxOrTTsPmXuXkbVb6LJr2JeSKFseCXWvlr > /X7UV5FJN50c3AJl5xu2xpoMDQtogu97 > -----END PUBLIC KEY----- > > > I don't think I can be of any more help unless you post code to reproduce > the problem that can be compiled and run a popular platform (preferably > Linux) without modifications, and also your library configuration > (mbedtls/config.h). Preferably post those on the mailing list, because I > personally have limited time and I'm not sure when I'll next be able to > take a look. > > Best regards, > > -- > Gilles Peskine > Mbed TLS developer > > > On 21/04/2021 14:14, stefano664 wrote: > > I'm sure that the problem isn't here. > > 1) mbedtls_base64_encode is used only to generate human readable data in > this case, and to print it. The chain have the same behaviour without these. > > 2) I changed len_b64 and olen type to size_t and removed casting. I have > the same result and verify fails... > > Here the new code: https://wtools.io/paste-code/b4Hy > > Here the new output: https://wtools.io/paste-code/b4H0 > > Do you have some other idea? > Thanks a lot for your help! > > Stefano > > > Il giorno mer 21 apr 2021 alle ore 13:36 Gilles Peskine < > gilles.peskine(a)arm.com> ha scritto: > >> Ok, I found the problem: >> >> mbedtls_base64_encode(hash_b64, sizeof(hash_b64), (size_t *) &len_b64, hash, 32); >> >> >> &len_b64 is a pointer to uint16_t. Casting the pointer to size_t* doesn't >> give you a pointer to a size_t object, it gives you an invalid pointer >> since it isn't pointing to a size_t object. When mbedtls_base64_encode >> writes through that pointer, it overwrites whatever is next on the stack. >> Other calls with a size_t* cast have the same problem. Depending on exactly >> how your compiler lays out the stack, this might part of the message, or >> part of the pk structure, or part of the result... >> >> I found this problem because I massaged your code until it ran on Linux, >> and it crashed during mbedtls_pk_sign because the pk structure had been >> corrupted. Other potential ways to find such problems include static >> analysis (Coverity is good but very expensive), AddressSanitizer (if you >> can build your code on a platform that has enough space), and of course >> code review (any cast is suspicious: most of the times, when a compiler >> complains about something, a cast will silence the compiler but not >> actually fix the problem). >> >> Best regards, >> >> -- >> Gilles Peskine >> Mbed TLS developer >> >> On 21/04/2021 09:43, stefano664 wrote: >> >> Hi Gilles, >> thanks for your reply. >> >> The posted code is without error checks to be smaller. The complete code >> is here: >> >> https://wtools.io/paste-code/b4Hi >> >> All error checks pass true than all functions seems ok. >> >> In this version I added also the verify, that fail. >> >> Here you can find the output with all prints, messages and datas: >> >> https://wtools.io/paste-code/b4Hj >> >> As you can see my signature is 71 byte wide, a bit too little even after >> zeroes removing. The same made with openSSL is 104 byte wide. >> I've checked my keys, and I confirm it is 384 bit. You can check, it is >> printed during process. >> >> Thanks a lot for your help! >> >> Best regards, >> Stefano >> >> >> Il giorno mar 20 apr 2021 alle ore 21:48 Gilles Peskine via mbed-tls < >> mbed-tls(a)lists.trustedfirmware.org> ha scritto: >> >>> Hi Stefano, >>> >>> Assuming that the key is in PEM format and that the buffers (hash, tmp) >>> are large enough, I don't see anything wrong in the part of the code you >>> posted. >>> >>> You posted code without error checking. Can you confirm that all >>> functions return 0? >>> >>> mbedtls_pk_sign produces ECDSA signatures in ASN.1 format. The size of >>> the signature can be up to 104 bytes, and is often a few bytes shorter >>> because it consists of numbers in which leading zeros are omitted. Make >>> sure the tmp buffer is large enough. You can use >>> MBEDTLS_ECDSA_MAX_SIG_LEN(384) or MBEDTLS_ECDSA_MAX_LEN (from >>> mbedtls/ecdsa.h) as the signature buffer size. >>> >>> 72 bytes is the maximum size of a signature for a 256-bit key, reached >>> about 25% of the time. Are you sure you're signing with the key you >>> intended? >>> >>> People may be able to help more if you post complete code that we can >>> run on our machine. >>> >>> Best regards, >>> >>> -- >>> Gilles Peskine >>> Mbed TLS developer >>> >>> On 20/04/2021 16:49, stefano664 via mbed-tls wrote: >>> > Hi all, >>> > I have some problems with mbedTLS during ECDSA signing process. >>> > >>> > I followed the example supplied with the source code and write this >>> code: >>> > >>> > mbedtls_pk_init(&pk); >>> > mbedtls_pk_parse_key(&pk, (const unsigned char *) >>> > flash.flash_ver0.ecc_priv_key, strlen(flash.flash_ver0.ecc_priv_key) + >>> > 1, (const unsigned char *)CA_DEF_ISSUER_PWD, CA_DEF_ISSUER_PWD_LEN); >>> > mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), msg, msg_len, >>> > hash); >>> > mbedtls_pk_sign(&pk, MBEDTLS_MD_SHA256, hash, 0, tmp, (size_t *)&len, >>> > mbedtls_ctr_drbg_random, &ctr_drbg); >>> > >>> > The private key is an ECC key with 384 bit. I have two issue: >>> > >>> > 1) In tmp variable I found the signature, but it is 72 byte, instead >>> > of 96 (384*2/87); >>> > 2) On this signature I try to make a verify, but fails. >>> > >>> > Where I'm wrong? >>> > >>> > Best regards, >>> > Stefano >>> > >>> >>> -- >>> 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. >> > > 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, 3 months

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3.0 proposal: remove support for pre-v3 X.509 certificate with extensions

by Manuel Pegourie-Gonnard

Hi all, Version 3 of X.509 was published in 1997 and introduced extensions. However, in the years that followed, some implementations did generate certificates with extensions and a declared version less than 3. Such certs were never compliant and are rejected by default, however we have a compile-time option to no reject them for that reason: MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3 Since this is 2021 and pre-v3 certificates are unlikely to still be used, we'd like to remove this option in Mbed TLS 3.0. (It would remain in 2.16 and the upcoming 2.x LTS branch.) As usual, more details can be found in the github issue: https://github.com/ARMmbed/mbedtls/issues/4386 If you need this option to still be available in Mbed TLS 3.0, please speak up now, here on on github! Regards, Manuel.

5 years, 3 months

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Re: [mbed-tls] SSL session cache API in Mbed TLS 3.0

by Jérémy Audiger

Hi Hanno, Regarding your first point, I'm not against having the structure mbedtls_ssl_session as opaque on the application side, at least, it ensures the application is not modifying something that it shouldn't. Having said that, on my side, I access three fields of this structure: * sslContext.state * sslContext.own_cid_len * sslContext.own_cid The first one is used to retrieve the current state, mainly MBEDTLS_SSL_HANDSHAKE_OVER, MBEDTLS_SSL_SERVER_HELLO_VERIFY_REQUEST_SENT. Finally, the match between an incoming LwM2M Client encrypted message using CID and the structure mbedtls_ssl_session is done by accessing own_cid / own_cid_len. But I think this one could be done using mbedtls_ssl_get_peer_cid(). Regards, Jérémy ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Hanno Becker via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: Friday, April 16, 2021 06:37 To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: [mbed-tls] SSL session cache API in Mbed TLS 3.0 Hi Mbed TLS enthusiasts, For Mbed TLS 3.0, we're considering to modify the API around SSL sessions and server-side SSL session caches as follows: 1) The mbedtls_ssl_session structure becomes opaque, that is, its layout, fields, size is not part of the API and thus not subject to any stability promises. Instances of mbedtls_ssl_session may only be accessed through public function API. At the time of writing, this is mainly mbedtls_ssl_session_load()/save() for session serialization and deserialization. In particular, user code requiring access to specific fields of mbedtls_ssl_session won't be portable without further adjustments, e.g. the addition of getter functions. If you access fields of mbedtls_ssl_session in your code and would like to retain the ability to do so, now is the time to speak up and let us know about your use case. 2) The SSL session cache API gets modified as proposed in https://github.com/ARMmbed/mbedtls/issues/4333#issuecomment-820297322: int mbedtls_ssl_cache_get( void *data, unsigned char const *session_id, size_t session_id_len, mbedtls_ssl_session *dst_session ); int mbedtls_ssl_cache_set( void *data, unsigned char const *session_id, size_t session_id_len, mbedtls_ssl_session const *session ); In words: The session ID becomes an explicit parameter. This modification is necessary because the present session cache API requires custom implementations to peek into the mbedtls_ssl_session structure, at least to inspect the session ID. With the session ID being added as an explicit parameter, this is no longer necessary. We propose that custom session cache implementations treat mbedtls_ssl_session instances opaquely and only use them through the serialization and deserialization API mbedtls_ssl_session_load()/save(). The reason why the proposed API does not operate on serialized data directly is that this would enforce unnecessary copies. If you are using a custom SSL server-side session cache implementation which accesses fields other than the session ID and which can not be implemented based on session serialization, now is the time to speak up and let us know about your use case. Kind regards, Hanno

5 years, 3 months

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Re: [mbed-tls] Signing messages with ECDSA

by Gilles Peskine

Hi Stefano, Assuming that the key is in PEM format and that the buffers (hash, tmp) are large enough, I don't see anything wrong in the part of the code you posted. You posted code without error checking. Can you confirm that all functions return 0? mbedtls_pk_sign produces ECDSA signatures in ASN.1 format. The size of the signature can be up to 104 bytes, and is often a few bytes shorter because it consists of numbers in which leading zeros are omitted. Make sure the tmp buffer is large enough. You can use MBEDTLS_ECDSA_MAX_SIG_LEN(384) or MBEDTLS_ECDSA_MAX_LEN (from mbedtls/ecdsa.h) as the signature buffer size. 72 bytes is the maximum size of a signature for a 256-bit key, reached about 25% of the time. Are you sure you're signing with the key you intended? People may be able to help more if you post complete code that we can run on our machine. Best regards, -- Gilles Peskine Mbed TLS developer On 20/04/2021 16:49, stefano664 via mbed-tls wrote: > Hi all, > I have some problems with mbedTLS during ECDSA signing process. > > I followed the example supplied with the source code and write this code: > > mbedtls_pk_init(&pk); > mbedtls_pk_parse_key(&pk, (const unsigned char *) > flash.flash_ver0.ecc_priv_key, strlen(flash.flash_ver0.ecc_priv_key) + > 1, (const unsigned char *)CA_DEF_ISSUER_PWD, CA_DEF_ISSUER_PWD_LEN); > mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), msg, msg_len, > hash); > mbedtls_pk_sign(&pk, MBEDTLS_MD_SHA256, hash, 0, tmp, (size_t *)&len, > mbedtls_ctr_drbg_random, &ctr_drbg); > > The private key is an ECC key with 384 bit. I have two issue: > > 1) In tmp variable I found the signature, but it is 72 byte, instead > of 96 (384*2/87); > 2) On this signature I try to make a verify, but fails. > > Where I'm wrong? > > Best regards, > Stefano >

5 years, 3 months

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Signing messages with ECDSA

by stefano664

Hi all, I have some problems with mbedTLS during ECDSA signing process. I followed the example supplied with the source code and write this code: mbedtls_pk_init(&pk); mbedtls_pk_parse_key(&pk, (const unsigned char *) flash.flash_ver0.ecc_priv_key, strlen(flash.flash_ver0.ecc_priv_key) + 1, (const unsigned char *)CA_DEF_ISSUER_PWD, CA_DEF_ISSUER_PWD_LEN); mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), msg, msg_len, hash); mbedtls_pk_sign(&pk, MBEDTLS_MD_SHA256, hash, 0, tmp, (size_t *)&len, mbedtls_ctr_drbg_random, &ctr_drbg); The private key is an ECC key with 384 bit. I have two issue: 1) In tmp variable I found the signature, but it is 72 byte, instead of 96 (384*2/87); 2) On this signature I try to make a verify, but fails. Where I'm wrong? Best regards, Stefano

5 years, 3 months

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Re: [mbed-tls] TLS serialization

by Manuel Pegourie-Gonnard

Hi Jérémy, Thanks for your question! Indeed, the context (de)serialization feature only support DTLS so far. We've added an enhancement request to our backlog to extend it to TLS: https://github.com/ARMmbed/mbedtls/issues/4340 However, it may take some time before we get to it, as we're currently focused on preparing Mbed TLS 3.0. Also, this enhancement may very well turn out to be more complex that it might look initially: TLS is a reliable stream protocol (as opposed to DTLS which is an unreliable datagram protocol) and there will probably be some precautions to take and corner case to handle in order to make sure the full stream is preserved. If you or anyone else wants to open a PR for that, that would obviously help - though again, I'm afraid we'll have little review bandwidth until the end of June. (More generally, it's always a good idea to coordinate on the list before raising a large or complex PR.) Regards, Manuel. ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Jérémy Audiger via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: 12 April 2021 18:39 To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: [mbed-tls] TLS serialization Hi everyone, I'm currently trying to add the ability to serialize / deserialize a TLS security session using these APIs: * mbedtls_ssl_context_load() * mbedtls_ssl_context_save() I'm on TLS Server-side (so not talking about TLS Client here). After digging through the mailing list, I discovered this previous topic: https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000012.html and this Github repository: https://github.com/dimakuv/mbedtls-psk-example The scenario is the same here: using PSK with ciphersuite MBEDTLS_TLS_PSK_WITH_AES_128_CCM_8 Once the handshake is done, I'm able to serialize the TLS session with the patch attached to this email. After that I'm able to decrypt one incoming packet and encrypt one ongoing packet. So, almost everything is fine. But, when the TLS Server is receiving another message from the TLS Client (message sent in two fragments), the Server is able to decrypt the first fragment but not the second one, getting this error: ssl_msg.c:5475: 0x7f9aa803d288: => read ssl_msg.c:4029: 0x7f9aa803d288: => read record ssl_msg.c:2012: 0x7f9aa803d288: => fetch input ssl_msg.c:2167: 0x7f9aa803d288: in_left: 0, nb_want: 5 ssl_msg.c:2192: 0x7f9aa803d288: in_left: 0, nb_want: 5 ssl_msg.c:2195: 0x7f9aa803d288: ssl->f_recv(_timeout)() returned 5 (-0xfffffffb) ssl_msg.c:2215: 0x7f9aa803d288: <= fetch input ssl_msg.c:3763: 0x7f9aa803d288: dumping 'input record header' (5 bytes) ssl_msg.c:3763: 0x7f9aa803d288: 0000: 17 03 03 00 41 ....A ssl_msg.c:3765: 0x7f9aa803d288: input record: msgtype = 23, version = [3:3], msglen = 65 ssl_msg.c:2012: 0x7f9aa803d288: => fetch input ssl_msg.c:2167: 0x7f9aa803d288: in_left: 5, nb_want: 70 ssl_msg.c:2192: 0x7f9aa803d288: in_left: 5, nb_want: 70 ssl_msg.c:2195: 0x7f9aa803d288: ssl->f_recv(_timeout)() returned 65 (-0xffffffbf) ssl_msg.c:2215: 0x7f9aa803d288: <= fetch input ssl_msg.c:3874: 0x7f9aa803d288: dumping 'input record from network' (70 bytes) ssl_msg.c:3874: 0x7f9aa803d288: 0000: 17 03 03 00 41 00 00 00 00 00 00 00 03 27 9d 1a ....A........'.. ssl_msg.c:3874: 0x7f9aa803d288: 0010: 50 14 ff e1 14 8c b0 f5 de 06 1c f0 43 5c a0 91 P...........C\.. ssl_msg.c:3874: 0x7f9aa803d288: 0020: 46 23 3e 42 86 ed 3a 48 38 3d e8 b4 05 09 50 ac F#>B..:H8=....P. ssl_msg.c:3874: 0x7f9aa803d288: 0030: 94 6b 9c fb c6 22 7b 46 62 e0 af 08 ab 60 50 3c .k..."{Fb....`P< ssl_msg.c:3874: 0x7f9aa803d288: 0040: 6d c6 c8 7c cb 2c m..|., ssl_msg.c:1301: 0x7f9aa803d288: => decrypt buf ssl_msg.c:1414: 0x7f9aa803d288: dumping 'additional data used for AEAD' (13 bytes) ssl_msg.c:1414: 0x7f9aa803d288: 0000: 00 00 00 00 00 00 00 02 17 03 03 00 31 ............1 ssl_msg.c:1423: 0x7f9aa803d288: dumping 'IV used' (12 bytes) ssl_msg.c:1423: 0x7f9aa803d288: 0000: db 70 01 4b 00 00 00 00 00 00 00 03 .p.K........ ssl_msg.c:1424: 0x7f9aa803d288: dumping 'TAG used' (8 bytes) ssl_msg.c:1424: 0x7f9aa803d288: 0000: 50 3c 6d c6 c8 7c cb 2c P<m..|., ssl_msg.c:1437: 0x7f9aa803d288: mbedtls_cipher_auth_decrypt() returned -25344 (-0x6300) ssl_msg.c:3900: 0x7f9aa803d288: ssl_decrypt_buf() returned -29056 (-0x7180) Between each emission or reception of the fragment, the TLS security context is loaded and saved into a database. The use case here is really interesting, it seems to work well except when I receive or emit a message split into multiple fragments. Something is lost during the session backup. Maybe an interesting thing to add is when I'm loading a TLS session from the database, I'm following these steps: * Load the session into a buffer from the database * Init a security session with mbedtls_ssl_init() and mbedtls_ssl_setup() * Load the session from the buffer with mbedtls_ssl_context_load() Since I'm not an expert of mbed TLS code, I would like to know if someone could help me investigate this issue. TLS serialization/deserialization could be interesting to be part of the mbed TLS library. Regards, Jérémy Audiger

5 years, 3 months

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3.0 Proposal: remove 3DES ciphersuites

by Manuel Pegourie-Gonnard

Hi all, We'd like to completely remove support for 3DES TLS ciphersuites in Mbed TLS 3.0. Those ciphersuites are vulnerable to the Sweet32 attack and 3DES has been deprecated by NIST. If we remove them from Mbed TLS 3.0, they will remain available in Mbed TLS 2.16 and 2.x, the latter being supported until 3 years after 3.0 has been released. As usual, if for any reason you need support for 3DES TLS ciphersuites in Mbed TLS 3.0, please speak up now and let use know about your use case! More context can be found at https://github.com/ARMmbed/mbedtls/issues/4367 Regards, Manuel.

5 years, 3 months

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3.0 proposal: remove support for MD2, MD4, RC4, Blowfish and XTEA

by Ronald Cron

Hi, We consider removing the support for MD2, MD4, RC4, Blowfish and XTEA from Mbed TLS 3.0 (but the support will remain in the 2.16 and 2.2x LTS branches for the course of their lifetime). If you use one of those cryptographic primitives and think it should remain in Mbed TLS 3.0, please let us know and explain why. You can find more information in the following GitHub issue: https://github.com/ARMmbed/mbedtls/issues/4084. Best regards, Ronald Cron.

5 years, 4 months

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SSL session cache API in Mbed TLS 3.0

by Hanno Becker

Hi Mbed TLS enthusiasts, For Mbed TLS 3.0, we're considering to modify the API around SSL sessions and server-side SSL session caches as follows: 1) The mbedtls_ssl_session structure becomes opaque, that is, its layout, fields, size is not part of the API and thus not subject to any stability promises. Instances of mbedtls_ssl_session may only be accessed through public function API. At the time of writing, this is mainly mbedtls_ssl_session_load()/save() for session serialization and deserialization. In particular, user code requiring access to specific fields of mbedtls_ssl_session won't be portable without further adjustments, e.g. the addition of getter functions. If you access fields of mbedtls_ssl_session in your code and would like to retain the ability to do so, now is the time to speak up and let us know about your use case. 2) The SSL session cache API gets modified as proposed in https://github.com/ARMmbed/mbedtls/issues/4333#issuecomment-820297322: int mbedtls_ssl_cache_get( void *data, unsigned char const *session_id, size_t session_id_len, mbedtls_ssl_session *dst_session ); int mbedtls_ssl_cache_set( void *data, unsigned char const *session_id, size_t session_id_len, mbedtls_ssl_session const *session ); In words: The session ID becomes an explicit parameter. This modification is necessary because the present session cache API requires custom implementations to peek into the mbedtls_ssl_session structure, at least to inspect the session ID. With the session ID being added as an explicit parameter, this is no longer necessary. We propose that custom session cache implementations treat mbedtls_ssl_session instances opaquely and only use them through the serialization and deserialization API mbedtls_ssl_session_load()/save(). The reason why the proposed API does not operate on serialized data directly is that this would enforce unnecessary copies. If you are using a custom SSL server-side session cache implementation which accesses fields other than the session ID and which can not be implemented based on session serialization, now is the time to speak up and let us know about your use case. Kind regards, Hanno

5 years, 4 months

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3.0 proposal: remove support for Truncated HMAC

by Manuel Pegourie-Gonnard

Hi everyone, Truncated HMAC is a TLS extension that was originally created to reduce overhead in constrained environments. Nowadays, CCM-8 ciphersuites are an alternative that's superior both in terms of having even lower overhead and in terms of security. Consequently, recent RFCs have stated that the Truncated HMAC extensions must no longer be used. So, we would like to entirely remove support for this extension from Mbed TLS 3.0. (LTS branches would obviously retain support for it.) If you need support for Truncated HMAC extension in Mbed TLS 3.0, please speak up now! More context and details can be found in this github issue, which can also be used for discussion: https://github.com/ARMmbed/mbedtls/issues/4341 Regards, Manuel.

5 years, 4 months

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TLS serialization

by Jérémy Audiger

Hi everyone, I'm currently trying to add the ability to serialize / deserialize a TLS security session using these APIs: * mbedtls_ssl_context_load() * mbedtls_ssl_context_save() I'm on TLS Server-side (so not talking about TLS Client here). After digging through the mailing list, I discovered this previous topic: https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000012.html and this Github repository: https://github.com/dimakuv/mbedtls-psk-example The scenario is the same here: using PSK with ciphersuite MBEDTLS_TLS_PSK_WITH_AES_128_CCM_8 Once the handshake is done, I'm able to serialize the TLS session with the patch attached to this email. After that I'm able to decrypt one incoming packet and encrypt one ongoing packet. So, almost everything is fine. But, when the TLS Server is receiving another message from the TLS Client (message sent in two fragments), the Server is able to decrypt the first fragment but not the second one, getting this error: ssl_msg.c:5475: 0x7f9aa803d288: => read ssl_msg.c:4029: 0x7f9aa803d288: => read record ssl_msg.c:2012: 0x7f9aa803d288: => fetch input ssl_msg.c:2167: 0x7f9aa803d288: in_left: 0, nb_want: 5 ssl_msg.c:2192: 0x7f9aa803d288: in_left: 0, nb_want: 5 ssl_msg.c:2195: 0x7f9aa803d288: ssl->f_recv(_timeout)() returned 5 (-0xfffffffb) ssl_msg.c:2215: 0x7f9aa803d288: <= fetch input ssl_msg.c:3763: 0x7f9aa803d288: dumping 'input record header' (5 bytes) ssl_msg.c:3763: 0x7f9aa803d288: 0000: 17 03 03 00 41 ....A ssl_msg.c:3765: 0x7f9aa803d288: input record: msgtype = 23, version = [3:3], msglen = 65 ssl_msg.c:2012: 0x7f9aa803d288: => fetch input ssl_msg.c:2167: 0x7f9aa803d288: in_left: 5, nb_want: 70 ssl_msg.c:2192: 0x7f9aa803d288: in_left: 5, nb_want: 70 ssl_msg.c:2195: 0x7f9aa803d288: ssl->f_recv(_timeout)() returned 65 (-0xffffffbf) ssl_msg.c:2215: 0x7f9aa803d288: <= fetch input ssl_msg.c:3874: 0x7f9aa803d288: dumping 'input record from network' (70 bytes) ssl_msg.c:3874: 0x7f9aa803d288: 0000: 17 03 03 00 41 00 00 00 00 00 00 00 03 27 9d 1a ....A........'.. ssl_msg.c:3874: 0x7f9aa803d288: 0010: 50 14 ff e1 14 8c b0 f5 de 06 1c f0 43 5c a0 91 P...........C\.. ssl_msg.c:3874: 0x7f9aa803d288: 0020: 46 23 3e 42 86 ed 3a 48 38 3d e8 b4 05 09 50 ac F#>B..:H8=....P. ssl_msg.c:3874: 0x7f9aa803d288: 0030: 94 6b 9c fb c6 22 7b 46 62 e0 af 08 ab 60 50 3c .k..."{Fb....`P< ssl_msg.c:3874: 0x7f9aa803d288: 0040: 6d c6 c8 7c cb 2c m..|., ssl_msg.c:1301: 0x7f9aa803d288: => decrypt buf ssl_msg.c:1414: 0x7f9aa803d288: dumping 'additional data used for AEAD' (13 bytes) ssl_msg.c:1414: 0x7f9aa803d288: 0000: 00 00 00 00 00 00 00 02 17 03 03 00 31 ............1 ssl_msg.c:1423: 0x7f9aa803d288: dumping 'IV used' (12 bytes) ssl_msg.c:1423: 0x7f9aa803d288: 0000: db 70 01 4b 00 00 00 00 00 00 00 03 .p.K........ ssl_msg.c:1424: 0x7f9aa803d288: dumping 'TAG used' (8 bytes) ssl_msg.c:1424: 0x7f9aa803d288: 0000: 50 3c 6d c6 c8 7c cb 2c P<m..|., ssl_msg.c:1437: 0x7f9aa803d288: mbedtls_cipher_auth_decrypt() returned -25344 (-0x6300) ssl_msg.c:3900: 0x7f9aa803d288: ssl_decrypt_buf() returned -29056 (-0x7180) Between each emission or reception of the fragment, the TLS security context is loaded and saved into a database. The use case here is really interesting, it seems to work well except when I receive or emit a message split into multiple fragments. Something is lost during the session backup. Maybe an interesting thing to add is when I'm loading a TLS session from the database, I'm following these steps: * Load the session into a buffer from the database * Init a security session with mbedtls_ssl_init() and mbedtls_ssl_setup() * Load the session from the buffer with mbedtls_ssl_context_load() Since I'm not an expert of mbed TLS code, I would like to know if someone could help me investigate this issue. TLS serialization/deserialization could be interesting to be part of the mbed TLS library. Regards, Jérémy Audiger

5 years, 4 months

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3.0 proposal: remove support for TLS 1.0, TLS 1.1 and DTLS 1.0

by Manuel Pegourie-Gonnard

Hi everyone, The IETF has recently published RFC 8996, which formally deprecates TLS 1.0, TLS 1.1 and DTLS 1.0 (there is no DTLS 1.1). One of the stated goals of the RFC is to empower maintainers of (D)TLS stacks to remove them from their code base, reducing the maintenance cost and the attack surface at the same time. This RFC comes right during the time we're preparing a new major version, which is the only time we allow ourselves to remove features. We'd like to take advantage of this opportunity by entirely removing support for TLS 1.0, TLS 1.1 and DTLS 1.0 in Mbed TLS 3.0. (They would obviously stay in our long-term support branches.) If you find yourself needing support for these versions in Mbed TLS 3.0, now is the time to speak up! More details can be found in the following github issue: https://github.com/ARMmbed/mbedtls/issues/4286 Feel free to discuss this issue on the list or on github, whatever's more convenient for you. Best regards, Manuel.

5 years, 4 months

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Mbed TLS 3.0 branching

by Dave Rodgman

Hello Mbed TLS users, As previously announced, we are going to switch the focus of Mbed TLS development onto the upcoming 3.0 release. * We have created the development_2.x branch, currently aligned with the tip of development * For the next two weeks, we will keep development and development_2.x in sync (daily) * On April 22, we will merge development_3.0 into development, and remove development_3.0 This means that after April 22: * development will contain API-breaking changes * new features will not normally be back-ported to development_2.x (unless there is a compelling reason to do so) * relevant bugfixes will be backported as normal Impact for users: * users of development should consider whether they should switch to using development_2.x * authors of PRs requiring backports may require an additional backport to development_2.x Regards Dave Rodgman

5 years, 4 months

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3.0 proposal: remove MBEDTLS_CHECK_PARAMS

by Gilles Peskine

Hello, I propose to remove the MBEDTLS_CHECK_PARAMS feature from Mbed TLS 3.0. (As with everything else, it will of course remain in the 2.16 and 2.2x long-time support branches.) If you are using MBEDTLS_CHECK_PARAMS and you think it should remain, please let us know and explain why. If you are not using this feature, I personally think that you're making the right choice. But if you're curious what it is, you can read the documentation or my description in https://github.com/ARMmbed/mbedtls/issues/4313 . -- Gilles Peskine Mbed TLS developer

5 years, 4 months

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Re: [mbed-tls] mbedtls_hmac_drbg_seed fails, returns MBEDTLS_ERR_ENTROPY_SOURCE_FAILED

by Gilles Peskine

Hi Jeff, It looks like you're using an old version of Mbed TLS. mbedtls_hmac_drbg_seed used to set ctx->entropy_len to entropy_len * 3 / 2, but this changed (https://github.com/ARMmbed/mbed-crypto/pull/238) to making a call to mbedtls_entropy_func for entropy_len and then one again for entropy_len / 2, precisely to avoid the scenario you're describing where the HMAC_DRBG module would request more entropy than the entropy can deliver in a single call. Please upgrade to the latest release of Mbed TLS, or the latest 2.16 release if you want a long-time support branch. The version you're using is old and has known vulnerabilities. -- Gilles Peskine Mbed TLS developer On 06/04/2021 13:59, Thompson, Jeff via mbed-tls wrote: > > ï¿½ > > The call flow is mbedtls_hmac_drbg -> mbedtls_hmac_drbg_reseed -> > mbedtls_entropy_func where the parameter, len, is 48 and > MBEDTLS_ENTROPY_BLOCK_SIZE is 32. I see that mbedtls_hmac_drbg_seed > sets ï¿½ctx->entropy_len = entropy_len * 3 / 2, which explains the size > difference. Iï¿½ve probably mis-configured (see attached) in order to > use TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA, because other ciphers take too > long. > > ï¿½ > > *Jeff Thompson*ï¿½| ï¿½Senior Electrical Engineer-Firmware > +1 704 752 6513 x1394 > www.invue.com <www.invue.com> > > ï¿½ > >

5 years, 4 months

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mbedtls_hmac_drbg_seed fails, returns MBEDTLS_ERR_ENTROPY_SOURCE_FAILED

by Thompson, Jeff

The call flow is mbedtls_hmac_drbg -> mbedtls_hmac_drbg_reseed -> mbedtls_entropy_func where the parameter, len, is 48 and MBEDTLS_ENTROPY_BLOCK_SIZE is 32. I see that mbedtls_hmac_drbg_seed sets ctx->entropy_len = entropy_len * 3 / 2, which explains the size difference. I've probably mis-configured (see attached) in order to use TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA, because other ciphers take too long. Jeff Thompson | Senior Electrical Engineer-Firmware +1 704 752 6513 x1394 www.invue.com [cid:image001.gif@01D72ABA.56C4A310]

5 years, 4 months

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Re: [mbed-tls] Mbed TLS mbedtls_ssl_config (struct) Question

by Manuel Pegourie-Gonnard

Hi Keith, Those are good questions, and the short answer is everything should work in a multi-threaded environment if Mbed TLS was built with threading support (for example, enabling MBEDTLS_THREADING_C and MBEDTLS_THREADING_PTHREAD in config.h). Now for some more details: regarding mbedtls_ssl_config, it is indeed treated as read-only by all function in the SSL/TLS module, except of course those functions that are explicitly meant to modify it (those whose name starts with mbedtls_ssl_conf_). So, if you set it up in the main thread and then use it in other threads, everything will be fine regarding the top-level structure itself (for sub-structures see below), regardless of whether threading support is enabled. For the DRBG contexts, you're right that each time we draw from them, they need to update their state. However, this is protected by a mutex if threading support was enabled at compile-time. A similar thing goes for private keys : RSA private keys are protected by a mutex if threading support is enabled (using them mutates state used for side-channel countermeasures), and ECDSA private keys are safe too. X.509 structures are always treated as read-only. Regarding documentation: we did recently expand the documentation on DRBGs: https://github.com/ARMmbed/mbedtls/commit/f305d92480c81c6eb02934a4e1af58152… Regarding SSL, I agree this should be better documented. If you'd like to open a PR to add documentation that would have answered your question, that would be very welcome. Regards, Manuel ________________________________ From: mbed-tls <mbed-tls-bounces(a)lists.trustedfirmware.org> on behalf of Keith Cancel via mbed-tls <mbed-tls(a)lists.trustedfirmware.org> Sent: 02 April 2021 06:43 To: mbed-tls(a)lists.trustedfirmware.org <mbed-tls(a)lists.trustedfirmware.org> Subject: [mbed-tls] Mbed TLS mbedtls_ssl_config (struct) Question Hello, I hope this a simple question regarding mbedtls_ssl_config. So it seems this structure is meant to be shared/used for multiple connections. However, if I have multiple threads is it treated as a read only structure by all the library code, or does it update some state at times? Similar thing regarding the mbedtls_x509_crt struct and mbedtls_ctr_drbg_context which also seem to be added to the config when I setup the config. I was hoping that once set I don’t have to worry about any mutexs/locks being used by the library under the hood. Mainly, that once the configuration is set in the main thread it state is never updated again. What made me curious about this is the fact the RNG seems to be part of the configuration and a CPRNG will generally have state that needs to change. Moreover, I can’t really find a clear answer looking at the docs. Thanks, Keith Cancel -- 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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mbed-tls