tree 60a19768b86feef8a43e2e2cdf2238ce64737734
parent ad27b8074f4196102291645d6aacaa96e21a4dc7
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> 1670241351 +0100
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> 1670576839 +0100

Use deterministic ECDSA in PSA when we do in legacy

This fixes the two failing cases in test_suite_pk when ECP_RESTARTABLE
and USE_PSA_CRYPTO are both enabled. The two failing cases where

    ECDSA restartable sign/verify: ECDSA, max_ops=0 (disabled)
    ECDSA restartable sign/verify: ECKEY, max_ops=0 (disabled)

associated with test function pk_sign_verify_restart(). The failure was
caused by the interaction of several things that are each reasonable on
their own:

1. The test function relies on ECDSA restartable, which is reasonable as it
allows making sure that the generated signature is correct with a simple
memcmp().
2. The implementation of pk_sign_restartable() has a shortcut to
dispatch to the sign function (as opposed to sign_restartable) when
restart is disabled (max_ops == 0).
3. When USE_PSA is enabled, the sign function dispatches to PSA, which
so far always used ECDSA (non-deterministic) even when the non-PSA
version would use deterministic ECDSA.

This could be fixed by changing any of those. I chose (3) because I
think it makes sense that when PK dispatches to PSA instead of legacy
this should not change which version of ECDSA is selected.

OTOH, I think it makes sense to keep (2), because that means more
opportunities to dispatch to PSA.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>