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Use deterministic ECDSA in PSA when we do in legacy

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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>
This commit is contained in:
Manuel Pégourié-Gonnard 2022-12-05 12:55:51 +01:00
parent ad27b8074f
commit 79ae7eb4d1
1 changed files with 5 additions and 0 deletions
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5
library/pk_wrap.c
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@ -1162,8 +1162,13 @@ static int ecdsa_sign_wrap( void *ctx_arg, mbedtls_md_type_t md_alg,
size_t key_len;
unsigned char buf[MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES];
unsigned char *p;
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
psa_algorithm_t psa_sig_md =
PSA_ALG_DETERMINISTIC_ECDSA( mbedtls_hash_info_psa_from_md( md_alg ) );
#else
psa_algorithm_t psa_sig_md =
PSA_ALG_ECDSA( mbedtls_hash_info_psa_from_md( md_alg ) );
#endif
size_t curve_bits;
psa_ecc_family_t curve =
mbedtls_ecc_group_to_psa( ctx->grp.id, &curve_bits );