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&am...

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

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