STM32H573 Secure Manager: TLS 1.3 HKDF-Extract/Expand not supported

[MarioM]

Hello,

I am integrating Mbed TLS with TLS 1.3 on an STM32H573 using the STM32 Secure Manager PSA interface.

The TLS 1.3 handshake fails at:

psa_key_derivation_setup(
    &operation,
    PSA_ALG_HKDF_EXTRACT(PSA_ALG_SHA_256));

The returned status is:

PSA_ERROR_NOT_SUPPORTED /* -134 */

I tested the relevant algorithms separately:

PSA_ALG_HKDF(PSA_ALG_SHA_256)
→ PSA_SUCCESS

PSA_ALG_HKDF_EXTRACT(PSA_ALG_SHA_256)
→ PSA_ERROR_NOT_SUPPORTED

PSA_ALG_HKDF_EXPAND(PSA_ALG_SHA_256)
→ PSA_ERROR_NOT_SUPPORTED

The generated algorithm ID is correct:

PSA_ALG_HKDF_EXTRACT(PSA_ALG_SHA_256) == 0x08000409U

I also traced the call through the Non-Secure PSA client. The request reaches the Secure Manager via nscall(), and PSA_ERROR_NOT_SUPPORTED is returned in psa_reply->status.

My questions are:

1. Does STM32 Secure Manager support PSA_ALG_HKDF_EXTRACT and PSA_ALG_HKDF_EXPAND?
2. Is support dependent on the Secure Manager or SMAK version?
3. Is TLS 1.3 with Mbed TLS officially supported with Secure Manager as PSA backend?
4. Is there an official workaround, for example local HKDF while keeping the private key inside Secure Manager?

Best regards,
Mario