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Merge pull request #5010 from gilles-peskine-arm/psa-rsa-pss_any_salt

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PSA: fix salt length for PSS verification
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Manuel Pégourié-Gonnard 2021-10-29 16:36:36 +02:00 • committed by GitHub
commit 4313d3ac87
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GPG key ID: 4AEE18F83AFDEB23
8 changed files with 314 additions and 49 deletions
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34
library/psa_crypto_rsa.c
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@ -453,6 +453,27 @@ exit:
return( status );
}
#if defined(BUILTIN_ALG_RSA_PSS)
static int rsa_pss_expected_salt_len( psa_algorithm_t alg,
const mbedtls_rsa_context *rsa,
size_t hash_length )
{
if( PSA_ALG_IS_RSA_PSS_ANY_SALT( alg ) )
return( MBEDTLS_RSA_SALT_LEN_ANY );
/* Otherwise: standard salt length, i.e. largest possible salt length
* up to the hash length. */
int klen = (int) mbedtls_rsa_get_len( rsa ); // known to fit
int hlen = (int) hash_length; // known to fit
int room = klen - 2 - hlen;
if( room < 0 )
return( 0 ); // there is no valid signature in this case anyway
else if( room > hlen )
return( hlen );
else
return( room );
}
#endif
static psa_status_t rsa_verify_hash(
const psa_key_attributes_t *attributes,
const uint8_t *key_buffer, size_t key_buffer_size,
@ -503,11 +524,14 @@ static psa_status_t rsa_verify_hash(
ret = mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V21, md_alg );
if( ret == 0 )
{
ret = mbedtls_rsa_rsassa_pss_verify( rsa,
md_alg,
(unsigned int) hash_length,
hash,
signature );
int slen = rsa_pss_expected_salt_len( alg, rsa, hash_length );
ret = mbedtls_rsa_rsassa_pss_verify_ext( rsa,
md_alg,
(unsigned) hash_length,
hash,
md_alg,
slen,
signature );
}
}
else