- mbed-tls - lists.trustedfirmware.org

Setting ciphersuite causes MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER

by Mbed TLS

My mbedtls client has been working for 2 years. It did what I required and has been stable. However, I now need to force a new server to use my preferred cipher suite. I found the helper function to force the cipher suite here: https://github.com/Mbed-TLS/mbedtls/blob/de4d5b78558666d2e258d95e6c5875f9c7… I added mbedtls_ssl_conf_preference_order(conf, MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_CLIENT) to the end of the function to force the server to choose my ciphersuite. Prior to this change I called the mbedtls functions in this chronological order: mbedtls_ssl_init(&_ssl); mbedtls_ssl_config_init(&_conf); mbedtls_ctr_drbg_init(&_ctr_drbg); mbedtls_entropy_init(&_entropy); mbedtls_x509_crt_init(&_cacert); mbedtls_pk_init(&_pkey); mbedtls_ctr_drbg_seed mbedtls_ssl_config_defaults mbedtls_ssl_conf_rng mbedtls_ssl_conf_authmode mbedtls_x509_crt_parse_file mbedtls_ssl_conf_ca_chain mbedtls_ssl_setup mbedtls_ssl_set_hostname and then proceed to call: mbedtls_ssl_set_bio mbedtls_ssl_handshake Now: If I call mbedtls_ssl_conf_ciphersuites BEFORE mbedtls_ssl_config_defaults, the ciphersuite list is ignored/seems to get overriden. If I call mbedtls_ssl_conf_ciphersuites AFTER mbedtls_ssl_config_defaults, my ciphersuite list changes are accepted and transmitted (I can see in Wireshark). The server then responds agreeing to use my chosen cipher suite. However, mbedtls_ssl_handshake returns with value -26112, which I have looked up to be MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER. Unfortunately I have no clue what is causing this. Could somebody please advise how this should be done? I can see Client2 example but there are functions I have which are not in there. Client1 seems too simple for me but Client2 seems beyond what I require.

1 year, 9 months

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Connect using IP address instead of URL "509 - Certificate verification failed, e.g. CRL, CA or signature check failed"

by M M

I am using MbedTLS client code based on this: https://github.com/machinezone/IXWebSocket/blob/master/ixwebsocket/IXSocket… I am connecting to a server via it's URL. However, I would like to connect directly using an IP address returned from running the traceroute command on the URL. So I replaced the URL with the IP address. However, MBedTLS fails on the handshake: https://github.com/machinezone/IXWebSocket/blob/master/ixwebsocket/IXSocket… I get the error: "error in handshake : X509 - Certificate verification failed, e.g. CRL, CA or signature check failed" If I revert back to URL, it works. The IP address does exist. How can I connect using the IP address, instead of the URL?

1 year, 9 months

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Re: mbedtls and PQC algorithms support

by Raunak Gupta

Micron Confidential Hi, I find that mbed-tls already support LMS, could you please Point to some reference and starting from which version mbedTLS lib version supports LMS? Best Regards, Raunak Get Outlook for iOS<https://aka.ms/o0ukef> Micron Confidential

1 year, 10 months

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Re: [EXT] RE: Inquiry About PQC Cryptos in embedTLS Library

by Raunak Gupta

Micron Confidential Dear MbedTLS, Can you please help to provide some references for LMS stateful signatures schemes support in MbedTLS, May be something like documentation and github repo link? Unfortunately I am not able to find it online? Thanks, Raunak Get Outlook for iOS<https://aka.ms/o0ukef> Micron Confidential ________________________________ From: Shebu Varghese Kuriakose <Shebu.VargheseKuriakose(a)arm.com> Sent: Tuesday, September 3, 2024 8:48 PM To: Raunak Gupta <raunakgupta(a)micron.com>; enquiries(a)trustedfirmware.org <enquiries(a)trustedfirmware.org> Cc: nd <nd(a)arm.com> Subject: [EXT] RE: Inquiry About PQC Cryptos in embedTLS Library Micron Confidential CAUTION: EXTERNAL EMAIL. Do not click links or open attachments unless you recognize the sender and were expecting this message. Hi Raunak, Mbed TLS today supports LMS stateful hash-based signature scheme. While supporting other PQC algorithms is in the Mbed TLS project roadmap, the team isn’t actively working on it. The focus for the team now is preparing for Mbed TLS 4.0. Feel free to ask any further technical questions in the Mbed TLS public mailing list - mbed-tls(a)lists.trustedfirmware.org<mailto:mbed-tls@lists.trustedfirmware.org> (https://lists.trustedfirmware.org/mailman3/lists/mbed-tls.lists.trustedfirm…) Regards, Shebu Micron Confidential From: 'Raunak Gupta' via TFenquiries <enquiries(a)trustedfirmware.org> Sent: Tuesday, September 3, 2024 2:34 AM To: enquiries(a)trustedfirmware.org Subject: Inquiry About PQC Cryptos in embedTLS Library Micron Confidential Dear Trusted Firmware Team, I hope this message finds you well. My name is Raunak, and I am a Security Engineer at Micron Technology. I would like to inquire whether the embedTLS library has been updated to include Post-Quantum Cryptography (PQC) algorithms such as LMS, HSS, and XMSS. Additionally, is the embedTLS team actively working on integrating these PQC algorithms? Thank you for your assistance. Best regards, Raunak Micron Confidential To unsubscribe from this group and stop receiving emails from it, send an email to enquiries+unsubscribe(a)trustedfirmware.org<mailto:enquiries+unsubscribe@trustedfirmware.org>.

1 year, 10 months

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Mbed TLS 3.6.1 and 2.28.9

by David Horstmann

Dear Mbed TLS users, We have released Mbed TLS versions 3.6.1 and 2.28.9. These releases provide bugfixes, security fixes and minor improvements. The 3.6.1 release includes fixes for issues caused by enabling TLS 1.3 for TLS connections in the default configuration. Full details are available in the release notes: https://github.com/Mbed-TLS/mbedtls/releases/tag/mbedtls-2.28.9 https://github.com/Mbed-TLS/mbedtls/releases/tag/mbedtls-3.6.1 We recommend all users to consider whether they are impacted, and to upgrade appropriately. Many thanks, David Horstmann Mbed TLS developer

1 year, 10 months

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Mbed TLS 4.0 roadmap and bignum/ecp API

by Gernot Kvas

Hi all, From the announcement and also the long term plans (https://mbed-tls.readthedocs.io/en/latest/project/long-term-plans/) it is apparent that bignum/ecp operations on the public API will go away and usage will be restricted to internal only. I do understand and welcome the shift towards PSA API and to abandon the ALT interface for higher level legacy API crypto functions. However, I'm not so positive about removal of the bignum and ecp API. There are projects using those functions even in their PSA porting layer (Matter comes to mind: https://github.com/project-chip/connectedhomeip/blob/master/src/crypto/CHIP…) or projects using the bignum layer as abstraction (Zephyr hostap/wpa_supplicant: https://github.com/zephyrproject-rtos/hostap/tree/main/src/crypto, crypto_mbedtls*.c). There might be a case to support those functions to have (hardware-accelerated) low level building blocks for algorithms Mbed TLS doesn't yet or never will support. As other SSL libraries such as OpenSSL also expose similar API (BN_ and EC_POINT_ ), the removal in Mbed TLS will certainly leave a gap. What's the view here from the project team? Cheers, Gernot

1 year, 10 months

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Requesting information for mbed-tls commercial license & support

by Kumar, Praveen

Hi, We are in the process of qualifying a suitable encryption library for our pre-hospital patient monitor and the telemedicine system. I am writing to request your guidance regarding the mbed-tls use for commercial purposes. I look forward to your response. Regards, Praveen Kumar R&D Project Manager Emergency Care Professional (EC-Pro) Philips Tel +44 (0) 1256 362427 Email praveen.m.kumar(a)philips.com<mailto:praveen.m.kumar@philips.com> Remote Diagnostic Technologies Limited. Registered office: Ascent 1, Farnborough Aerospace Centre, Aerospace Boulevard, Farnborough GU14 6XW, UK. Registered in England No. 3321782. [Logo Description automatically generated]<http://www.philips.com/> Connect with Philips [cid:image002.gif@01DAE7F8.0802FC50]<https://www.linkedin.com/company/philips/>[cid:image003.gif@01DAE7F8.0802FC50]<https://twitter.com/PhilipsHealth>[cid:image004.gif@01DAE7F8.0802FC50]<https://www.youtube.com/PhilipsHealthcare/videos> ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

1 year, 10 months

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Major changes in Mbed TLS 4.0

by Gilles Peskine

Hello, Following consultations with the community and internal discussions among the Mbed TLS maintenance team, we can now present the major changes that will happen in the next major version of Mbed TLS. Our plan remains to release in the second quarter of 2025. The next major version will focus on two things: 1. The cryptography library will be a separate product called TF-PSA-Crypto 1.0. The X.509 and TLS library will be called Mbed TLS 4.0, and will rely on TF-PSA-Crypto for all cryptographic functionality. 2. This release completes the migration of cryptography APIs from classic mbedtls APIs to PSA APIs. Please find more information below about what this means in practice. What follows are just headlines, not an exhaustive list of changes. We expect many small changes that do not affect major functionality. Please note that the changes presented here are our current plan. We may revise it based on new inputs, new insights or unexpected hurdles. You can follow the advancement of the design, planning and development of the next release on the 4.0+1.0 planning board at https://github.com/orgs/Mbed-TLS/projects/15/views/1 . Removal of legacy APIs The following low-level application interfaces will no longer be present in the API of TF-PSA-Crypto 1.0 and Mbed TLS 4.0: * Hashes: hkdf.h, md5.h, ripemd160.h, sha1.h, sha3.h, sha256.h, sha512.h; * Random generation: ctr_drbg.h, hmac_drbg.h, entropy.h; * Ciphers and modes: aes.h, aria.h, camellia.h, chacha20.h, chachapoly.h, cipher.h, cmac.h, gcm.h, poly1305.h; * Private key encryption mechanisms: pkcs5.h, pkcs12.h. * Asymmetric cryptography: bignum.h, dhm.h, ecdh.h, ecdsa.h, ecjpake.h, ecp.h, rsa.h. The cryptographic mechanisms remain present, but they will only be accessible via the PSA API (psa_xxx functions introduced gradually starting with Mbed TLS 2.17). If you maintain code that uses these interfaces, you can already start migrating it today, since almost all PSA interfaces are available in the mbedtls-3.6 long-time support branch (and many even in 2.28 LTS). Please consult the PSA transition guide https://github.com/Mbed-TLS/mbedtls/blob/mbedtls-3.6/docs/psa-transition.md for guidance. Some non-PSA crypto interfaces will still be present in TF-PSA-Crypto 1.0: * pk.h will remain with some changes, mainly to provide an interface to key parsing and formatting which does not have a PSA equivalent yet. * md.h will remain as a thin layer over PSA hash functions (not HMAC) to ease the transition. * nist_kw.h will remain because it does not have a PSA equivalent yet. Removal of legacy integration interfaces TF-PSA-Crypto 1.0 and Mbed TLS 4.0 will no longer support MBEDTLS_xxx_ALT replacement of functions and modules. Use PSA transparent drivers instead. TF-PSA-Crypto 1.0 and Mbed TLS 4.0 will no longer support MBEDTLS_PK_RSA_ALT and MBEDTLS_PSA_CRYPTO_SE_C. Use PSA opaque drivers instead. TF-PSA-Crypto 1.0 and Mbed TLS 4.0 will no longer have the mbedtls/entropy.h interface to configure entropy sources. This will be replaced by PSA random drivers. In addition, we are planning to rework the platform abstraction layer (MBEDTLS_PLATFORM_xxx configuration options). More details will be available in the coming months. Removal of legacy mechanisms The following cryptographic mechanisms are planned to be removed in TF-PSA-Crypto 1.0 and Mbed TLS 4.0: * DES (including 3DES). * PKCS#1v1.5 encryption/decryption (RSAES-PKCS1-v1_5). (OAEP, PSS, and PKCS#1v1.5 signature are staying.) * Finite-field Diffie-Hellman with custom groups. (RFC 7919 groups remain supported.) * Elliptic curves of size 225 bits or less. The following cipher suites are planned to be removed from (D)TLS 1.2 in Mbed TLS 4.0: * TLS_RSA_* (including TLS_RSA_PSK_*), i.e. cipher suites using RSA decryption. (RSA signatures, i.e. TLS_ECDHE_RSA_*, are staying.) * TLS_ECDH_*, i.e. cipher suites using static ECDH. (Ephemeral ECDH, i.e. TLS_ECDHE_*, is staying.) * TLS_DHE_*, i.e. cipher suites using finite-field Diffie-Hellman. (Ephemeral ECDH, i.e. TLS_ECDHE_*, is staying.) * TLS_*CBC*, i.e. all cipher suites using CBC. Non-functional changes Due to the separation into two separate products (TF-PSA-Crypto and Mbed TLS), there will be major changes to the directory structure and to the build system. We plan to use CMake as the primary build system. Since TF-PSA-Crypto is a new product, identifiers that are not PSA interfaces (such as optimisation options and platform interfaces) will be renamed with a new prefix. Best regards, -- Gilles Peskine Mbed TLS developer

1 year, 10 months

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Usage of ECB in AES mode

by Chaitanya Tata

Hi, ECB is unsecure, see https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Electronic_cod… and shouldn't be used in production. So, I have switched to one of CBC/CMAC/CTR modes, but in `mbedtls_cipher_cmac_starts` I see that it only accepts ECB variants, and also doesn't seem to be using the `type`. From https://github.com/Mbed-TLS/mbedtls/issues/8617 I see that ECB for AES was intentional, even for the CMAC API. Is this expected? 1. Is using ECB for CMAC API correct? 2.Shouldn't we remove the ECB altogether? Appreciate any clarifications. Cheers, Chaitanya.

1 year, 10 months

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[Hyosung TNS] Request a quote for embedded encryption library

by SHIN JAE WHAN(신재환)

Dear Trusted Firmware, I’m Jay, an embedded security firmware developer at Hyosung TNS<https://global.hyosunginnovue.com/?lang_switch>. We are a company that manufactures ATMs. For cryptographic communication between ATM PC software and ATM devices, we are looking for a cryptographic library to apply to ATM devices(e.g. cash dispenser). If there is an appropriate library that meets the requirements below, I would appreciate it if you could provide us an estimate. If custom development is required, I would also like to know the expected development period. [Development environment] - CPU : TI AM1806(ARM9) - Compiler : ARM DS-5(armcc) - RTOS : ThreadX - C language - No dynamic allocation - VFP(Vectored Floating Point) not supported [Security Features] - RSA(2048bits) : Certificate and signature verification, Data encryption and decryption - ECC(256bits) : Generating a symmetric key using ECDH and ECDSA - 3DES, AES, AEAD, SHA256, HMAC256, etc : Algorithms related to data encryption and decryption - Random : Prevent replay attacks Please contact me if you have any questions. Best Regards, Jay [cid:image001.png@01DAE289.1B3D4C90] Jaewhan Shin Performance Manager | CISSP | Firmware Development Team Suseo Bldg., 281, Gwangpyeong-ro, Gangnam-gu, Seoul, 06349 Korea t. 82-2-6181-2480, m. 82-10-8158-3015 e. jaewhan.shin(a)hyosung.com<mailto:jaewhan.shin@hyosung.com> hyosunginnovue.com<https://hyosunginnovue.com/> [cid:image002.png@01DAE289.1B3D4C90]<https://www.linkedin.com/company/hyosung-tns/> [cid:image003.png@01DAE289.1B3D4C90] <https://www.youtube.com/@hyosungtns3918> HYOSUNG TNS, Inc. Email Disclaimer. This communication, including attachments, is intended only for the exclusive use of addressee and may contain proprietary, confidential, or privileged information. Any use, review, duplication, disclosure, dissemination, or distribution is strictly prohibited. If you were not the intended recipient, and you have received this communication in error, please notify sender immediately by return e-mail, delete this communication, and destroy any copies.

1 year, 11 months

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TLS 1.3 failures in Mbed TLS 3.6.0

by Gilles Peskine

Hello, Mbed TLS 3.6.0 was the first release to enable TLS 1.3 support by default. Unfortunately, this breaks many applications that open a TLS connection with default settings, which are now negotiating TLS 1.3 instead of TLS 1.2, but hit a difference in how Mbed TLS 3.6.0 implements the two versions of the protocol. The most common symptom is: you are using the default configuration (or something close), and your application fails in the handshake with an internal error whenever it negotiates TLS 1.3. To resolve this, call psa_crypto_init() before starting a TLS handshake. For a list of other known issues, please see https://github.com/Mbed-TLS/mbedtls/issues/9223 If you are encountering a problem due to the enablement of TLS 1.3 that is not listed on that page, please let us know by opening an issue on GitHub. If no workaround or patch is available for your problem yet, you can disable TLS 1.3 by calling mbedtls_ssl_conf_max_tls_version(ssl_config, MBEDTLS_SSL_VERSION_TLS1_2) before mbedtls_ssl_setup(). We are planning to fix all the issues listed on that page before the 3.6.1 patch release. We do not yet have a date for the 3.6.1 release. Best regards, -- Gilles Peskine Mbed TLS developer

1 year, 11 months

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TLS-Exporter in TLS 1.3

by Maximilian Fillinger

Hello! I am trying to add TLS 1.3 support to OpenVPN when using Mbed TLS as the TLS library. My current roadblock is that OpenVPN needs the TLS-Exporter functionality (RFC 8446, Section 7.5). For TLS 1.2, we get the master secret through mbedtls_ssl_set_export_keys_cb() and then implement the exporter using mbedtls_ssl_tls_prf(). For TLS 1.3, an approach like this doesn't work because the callback isn't called with the exporter master secret. Am I missing anything, or does this feature not yet exist? Are there any plans to add it? If not, I'd be interested in trying to make a patch. Best regards, Max

1 year, 11 months

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bestwritercontent

by hma3yf39＠mediaholy.com

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1 year, 11 months

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[Mbed-tls-announce] Requests for feedback about Mbed TLS 4: summary

by Gilles Peskine via Mbed-tls-announce

Hello, In the past few weeks, we have sent a number of requests for feedback on the mbed-tls mailing list about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). Most are about features that we may remove because we think they are not used much and are not worth maintaining. This message is a summary of the requests. If you have concerns about any of these topics, please reply on the GitHub issue (preferred), or on the mbed-tls mailing list, or by private email. (If you reply privately, we will anonymize before sharing outside Arm.) Please reply before 31 July so that we have time to plan 4.0 preparation. While we won't ignore later replies, they will be harder to accommodate. List archive: https://lists.trustedfirmware.org/archives/search?count=25&q=feedback&page=… GitHub links — cryptographic mechanisms https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/102 — Custom ECC mechanisms https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/104 — Custom RSA mechanisms https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/105 — Import of incomplete RSA private keys https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/107 — Direct access to CTR_DRBG and HMAC_DRBG https://github.com/Mbed-TLS/mbedtls/issues/8459 — RSA PKCS#1v1.5 encryption https://github.com/Mbed-TLS/mbedtls/issues/9164 — DES (including 3DES) GitHub links — cryptography implementations https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/103 — Partial ECC acceleration https://github.com/Mbed-TLS/mbedtls/issues/8151 — Dynamically registered secure element drivers GitHub links — TLS 1.2 https://github.com/Mbed-TLS/mbedtls/issues/5278 — FFDH in TLS 1.2 https://github.com/Mbed-TLS/mbedtls/issues/8170 — RSA decryption cipher suites (RSA without DH/ECDH) https://github.com/Mbed-TLS/mbedtls/issues/9201 — Static ECDH cipher suites https://github.com/Mbed-TLS/mbedtls/issues/9202 — CBC cipher suites <https://github.com/Mbed-TLS/mbedtls/issues/9201> GitHub links — platform https://github.com/Mbed-TLS/mbedtls/issues/8108 — Platform interface redesign https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/106 — Building with plain make or CMake https://github.com/Mbed-TLS/mbedtls/issues/8231 — x86_64: AESNI without compiler intrinsics https://github.com/Mbed-TLS/mbedtls/issues/9307 — Support for %zu in printf If you have an opinion on a topic where we haven't requested feedback, you can find our (rapidly evolving) planning board at https://github.com/orgs/Mbed-TLS/projects/15/views/1 . As a reminder, the main focus of the release will be that all cryptography goes through PSA APIs. Low-level legacy cryptography APIs (bignum.h, rsa.h, aes.h, etc.) will no longer be public. Except as indicated here, we generally intend feature parity, but it's possible that we've missed some unusual scenario, so please let us know if you have concerns. Best regards, -- 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-announce mailing list -- mbed-tls-announce(a)lists.trustedfirmware.org To unsubscribe send an email to mbed-tls-announce-leave(a)lists.trustedfirmware.org

1 year, 11 months

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Reminder: MBed TLS Tech Forum - Asia/Europe

by Don Harbin

Hi All, A gentle reminder that the Asia-Europe timezone-friendly MBed TLS Tech forum is next Monday at 10:00am PM UK time. Invite details can be found on the online calendar here <https://www.trustedfirmware.org/meetings/>. If you have any topics, please let Dave Rodgman know. :) Best regards, Don Harbin TrustedFirmware Community Manager don.harbin(a)linaro.org ReplyReply to allForward Compose: Community activity: OpenCV, Sensors, AI [image: Minimise][image: Pop-out][image: Close] Compose: Reminder: MBed TLS Tech Forum - Asia/Europe [image: Minimise][image: Pop-out][image: Close] Recipients

1 year, 12 months

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Can TLS client send `Encrypted Alert 21` to server

by Satya Prakash Prasad

Hi All, We are using the MBedTLS 3.6.0 release stack and often see the TLS client -> server sending Encrypted Alert 21 packets followed by closing the SSL connection (or rather reconnection starting from new handshake messages). As far as I understand Alert 21 is a fatal message stating Decryption of a TLSCiphertext record is decrypted in an invalid way: either it was not an even multiple of the block length or its padding values, when checked, were not correct - copied from the Internet. But then Handshake and Application Data goes thru fine for a while and then we see our client sending Alert 21 encrypted message Is it legitimate that the client can send Alert 21 messages to the server and close the current connection - we are observing that the server application is waiting for messages from the client and is un-aware that a connection reset has occurred. So the server application states a timeout for receiving messages from the client. Further, how can we assert such a scenario? When and how can it occur? Is there a way we can simulate it and send details to owners of server firmware to fix their issue? Regards, Prakash

2 years

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FIPS 140-3 compliance of MbedTLS Test suites

by Viktor.Ivanets＠infineon.com

Hi All, We are using MbedTLS on our devices and implementing PSA wrappers to use our Crypto hardware. For validating this one we are using MbedTLS test suites. Could you please tell me: 1. Does your test suites compliant to FIPS 140-3? 2. Do you use NIST test vectors to validate your algorithm implementations? Thanks. Viktor Ivanets.

2 years

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3.6.0 library size

by Steven Burck

On a project at my company, we're using mbedtls to encrypt and sign our data. We began the project with mbedtls 2.2.6, and have continuously upgraded until now, 3.6.0. I've noticed my application has grown greatly since then, even though we are only using the following APIs: Encryption:(only decryption on the embedded side) - mbedtls_aes_init - mbedtls_aes_setkey_dec - mbedtls_aes_crypt_cbc Signing (only verification on the embedded side) - mbedtls_ecp_point_read_binary - mbedtls_sha256_init/free - mbedtls_sha256_starts_ret - mbedtls_sha256_update_ret - mbedtls_sha256_finish_ret - mbedtls_ecdsa_init/free - mbedtls_ecp_group_load - mbedtls_ecdsa_read_signature The size of libembedcrypto.a has grown from under 400K to almost 800K. I've tried reducing it with mbedtls_config,h, but it is not entirely clear to me which #defines do what. I tried one of the sample configs which by it;s name looked promising (crypto-config-ccm-aes-sha256.h), and it reduced the size of the library by 90%, but left me with link errors for all of the above functions. Going one #define at a time manually to see if it saves or grows is slow, and so I hoped I could find some assistance here. Thanks in advance

2 years

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Question about random number g

by Zhang, Hao

Hi TF-M and mbedtls community, I am new to TF-M, I have a few questions about CryptoCell and random number generation. Thank you in advance. 1. I figure there seems to have two CryptoCell 312 implementations within TF-M. One under lib/ext/cryptocell-312-runtime and the other under platform/ext/accelerator/cc312/cc312-rom. What are the difference between these two? 2. For lib/ext/cryptocell-312-runtime, it does not define MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG whereas /ext/accelerator/cc312/cc312-rom does. Does that mean cryptocell-312-runtime is initiating RNG cryptodriver by using mbedtls_entropy_add_source whereas cc312-rom is using mbedtls_psa_external_get_random<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…>. If so, may I ask why these two cryptocells take two different approaches? I read from one of the documentation that mbedtls_psa_external_get_random is used when entropy is sufficient. So if entropy is sufficient, is it always preferred to have MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG defined and implements mbedtls_psa_external_get_random? What are the differences between the two approaches. 3. I also found cryptocell-312-runtime defines the entry point function cc3xx_init_random<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…>. But since PSA random number entry point funciton is not complete, the cc3xx_init_random is not being called anywhere, right? [https://opengraph.githubassets.com/17cdebc400b0ed807c620b586b21f3f77ff9c5d3…]<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…> trusted-firmware-m/platform/ext/accelerator/cc312/cc312-rom/psa_driver_api/src/cc3xx_psa_random.c at 8df9cc8baf46252fd188bba1d87333a8daa9a5e8 · zephyrproject-rtos/trusted-firmware-m<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…> Zephyr repository tracking https://git.trustedfirmware.org/trusted-firmware-m.git/ - zephyrproject-rtos/trusted-firmware-m github.com 4. I know random number generation PSA entry point function is in development, may I ask when that would be expected to complete? Thank you very much! Best regards, Hao

2 years

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Request for feedback about Mbed TLS 4: DRBG interfaces

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/107 Should TF-PSA-Crypto 1.0 (and thus Mbed TLS 4.0) have an interface for *pseudo*-random generation? It will, of course, still have a pseudorandom generator (= deterministic random bit generator = DRBG) internally, to power psa_generate_random(), psa_generate_key(), etc. The question is whether there will still be a public interface to create other DRBG instances, and if so, with what interface. If you want to be able to create instances of HMAC_DRBG and CTR_DRBG from application code in TF-PSA-Crypto 1.0, please let us know what your use case is. In particular, what parameters do you need (HMAC_DRBG and CTR_DRBG have many)? Do you need reseeding, and if so under whose control (the DRBG, or the caller)? In the absence of feedback, it is likely that HMAC_DRBG and CTR_DRBG will not be publicly available. Best regards, -- Gilles Peskine Mbed TLS developer

2 years

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mbedtls 3.6.0: zero-sized array gives compiler warning (is undefined behavior)

by Almut Herzog

Hi all, I have a custom configuration where MBEDTLS_ECDSA_C is defined but MBEDTLS_PSA_CRYPTO_C and MBEDTLS_PSA_CRYPTO_CONFIG are not. This leads to a compiler warning in e.g. psa_util.c because a zero-sized array is declared (because PSA_VENDOR_ECC_MAX_CURVE_BITS is defined as 0). As of C99, §6.7.5.2 Array declarators: "If the expression is a constant expression, it shall have a value greater than zero." psa_util.c: #if defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA) // Line 368 int mbedtls_ecdsa_raw_to_der(...) // Line 433 unsigned char r[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)]; // Line 436 --> becomes in my config: unsigned char r[0]; MBEDTLS_PSA_UTIL_HAVE_ECDSA is automatically defined in my configuration due to the following code in config_adjust_legacy_crypto.h: #if defined(MBEDTLS_ECDSA_C) || (defined(MBEDTLS_PSA_CRYPTO_C) && \ (defined(PSA_WANT_ALG_ECDSA) || defined(PSA_WANT_ALG_DETERMINISTIC_ECDSA))) #define MBEDTLS_PSA_UTIL_HAVE_ECDSA #endif PSA_VENDOR_ECC_MAX_CURVE_BITS only receives a non-zero value if a PSA_WANT_<CURVE>, e.g. PSA_WANT_ECC_BRAINPOOL_P_R1_256, is defined. PSA_WANT_<CURVE> only gets defined in crypto_config.h if MBEDTLS_PSA_CRYPTO_CONFIG is defined (which it is not in my configuration). I have worked around it by explicitly defining e.g. PSA_WANT_ECC_BRAINPOOL_P_R1_256 in my configuration. But I believe there is some mismatch in the defines, at least in this example case, because mbedtls_ecdsa_raw_to_der() is only used in pk_wrap.c if MBEDTLS_USE_PSA_CRYPTO is defined. Impact: * In general, zero-sized arrays have undefined behavior in C (but are allowed by some compiler extensions) and thus behave differently for different compilers --> you might want to review PSA_VENDOR_ECC_MAX_CURVE_BITS and PSA_VENDOR_FFDH_MAX_KEY_BITS (and possibly more definitions) that fall through to 0 and are used as array sizes. * In my particular case, I believe code is compiled that is not needed (defines in psa_util.c and pk_wrap.c do not seem to match)

2 years

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Request for feedback about Mbed TLS 4: size_t printing with %zu

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/9307 Mbed TLS requires a C99 platform, with some pragmatic restrictions. One restriction is that we do not require printf and friends to support %zu for size_t printing. Starting with Mbed TLS 4.0, we are considering requiring printf() and friends (or the mbedtls_printf() and friends alternatives if overridden) to support %zu. This only affects the TLS library, not X.509 and crypto. Is it still necessary in 2025 to support platforms where printf() does not support the z modifier? Best regards, -- Gilles Peskine Mbed TLS developer

2 years

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Request for feedback about Mbed TLS 4 and TF-PSA-Crypto: build system

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/106 We are evaluating build systems for TF-PSA-Crypto, and this will influence the Mbed TLS build as well (the Mbed TLS build scripts will call the TF-PSA-Crypto build scripts, whatever they are). Our current thinking is that we would like to have *CMake as the sole build system*. (We're still investigating whether CMake can do all we need.) That would mean that we would no longer provide GNU makefiles or Visual Studio solutions. As this remains a C project, for just building the library, compiling all the .c files with an include path covering all the .h files will keep working in common cases (but, as today, it isn't something we support officially). The main case I can think of where this wouldn't work is when cryptographic accelerator support requires special includes or compiler flags. Are there environments where the use of CMake is a problem? What is the oldest version of CMake that you'd like us to be compatible with? Best regards, -- Gilles Peskine Mbed TLS developer

2 years

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Request for feedback about Mbed TLS 4: RSA decryption cipher suites

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/8170 We are considering removing support for RSA and RSA-PSK key exchanges in Mbed TLS 4. These are cipher suites that use RSA encryption, as opposed to cipher suites using a key agreement (ECDHE) plus RSA signature. These key exchanges are hard to implement securely (we believe we got it right, but it's very delicate code), and they add significantly to the complexity of the TLS code. They have been formally deprecated for a long time and were removed in TLS 1.3. However, I'm aware that some ecosystems are clinging to RSA key exchange. Are RSA-encryption key exchanges still relevant for Mbed TLS? If you want Mbed TLS 4 to keep supporting RSA-encryption cipher suites in TLS 1.2, please let us know and tell us about your use cases. Best regards, -- Gilles Peskine Mbed TLS developer

2 years

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Request for feedback about Mbed TLS 4: AESNI without compiler intrinsics

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/8231 We currently have two implementations of accelerated AES on x86_64 using AESNI (Intel AES acceleration): using assembly or using compiler intrinsics. The assembly code works with GCC and Clang without any compilation options, but not with MSVC. The intrinsics work with MSVC, but not with ancient GCC/Clang and they require compiling at least aesni.c with suitable CPU variant options (e.g. -maes -mpclmul for Clang). We're considering removing the assembly implementation. Is there still interest in compiling AESNI support with older compilers or with simple build systems that don't pass machine options? Best regards, -- Gilles Peskine Mbed TLS developer

2 years

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