Add implementation of mbedtls_pk_can_do_ext()
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/library/pk.c b/library/pk.c
index 42ff432..bcb6263 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -232,6 +232,94 @@
return( ctx->pk_info->can_do( type ) );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+/*
+ * Tell if a PK can do the operations of the given PSA algorithm
+ */
+int mbedtls_pk_can_do_ext( const mbedtls_pk_context *ctx, psa_algorithm_t alg )
+{
+ /* A context with null pk_info is not set up yet and can't do anything.
+ * For backward compatibility, also accept NULL instead of a context
+ * pointer. */
+ if( ctx == NULL || ctx->pk_info == NULL )
+ return( 0 );
+
+ /* Filter out non allowed algorithms */
+ if( PSA_ALG_IS_ECDSA( alg ) == 0 &&
+ PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) == 0 &&
+ PSA_ALG_IS_RSA_PSS( alg ) == 0 &&
+ alg != PSA_ALG_RSA_PKCS1V15_CRYPT &&
+ PSA_ALG_IS_ECDH( alg ) == 0 )
+ return( 0 );
+
+ /* Wildcard hash is not allowed */
+ if( PSA_ALG_IS_SIGN_HASH( alg ) &&
+ PSA_ALG_SIGN_GET_HASH( alg ) == PSA_ALG_ANY_HASH )
+ return( 0 );
+
+ if( mbedtls_pk_get_type( ctx ) != MBEDTLS_PK_OPAQUE )
+ {
+ mbedtls_pk_type_t type;
+
+ if( PSA_ALG_IS_ECDSA( alg ) || PSA_ALG_IS_ECDH( alg ) )
+ type = MBEDTLS_PK_ECKEY;
+ else if( PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) ||
+ alg == PSA_ALG_RSA_PKCS1V15_CRYPT )
+ type = MBEDTLS_PK_RSA;
+ else if( PSA_ALG_IS_RSA_PSS( alg ) )
+ type = MBEDTLS_PK_RSASSA_PSS;
+ else
+ return( 0 );
+
+ return( ctx->pk_info->can_do( type ) );
+ }
+
+ const mbedtls_svc_key_id_t *key = (const mbedtls_svc_key_id_t *) ctx->pk_ctx;
+ psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+ psa_algorithm_t key_alg, key_alg2;
+ psa_status_t status;
+
+ status = psa_get_key_attributes( *key, &attributes );
+ if( status != PSA_SUCCESS )
+ return( 0 );
+
+ key_alg = psa_get_key_algorithm( &attributes );
+ key_alg2 = psa_get_key_enrollment_algorithm( &attributes );
+ psa_reset_key_attributes( &attributes );
+
+ /*
+ * Common case: the key alg & alg2 only allows alg.
+ * This will match PSA_ALG_RSA_PKCS1V15_CRYPT & PSA_ALG_IS_ECDH
+ * directly.
+ * This would also match ECDSA/RSA_PKCS1V15_SIGN/RSA_PSS with
+ * a fixed hash on key_alg/key_alg2.
+ */
+ if( alg == key_alg || alg == key_alg2 )
+ return( 1 );
+
+ /*
+ * If key alg or alg2 is a hash-and-sign with a wildcard for the hash,
+ * and alg is the same hash-and-sign family with any hash,
+ * then alg is compliant with this key alg
+ */
+ if( PSA_ALG_IS_SIGN_HASH( alg ) )
+ {
+
+ if( PSA_ALG_IS_SIGN_HASH( key_alg ) &&
+ PSA_ALG_SIGN_GET_HASH( key_alg ) == PSA_ALG_ANY_HASH &&
+ ( alg & ~PSA_ALG_HASH_MASK ) == ( key_alg & ~PSA_ALG_HASH_MASK ) )
+ return( 1 );
+
+ if( PSA_ALG_IS_SIGN_HASH( key_alg2 ) &&
+ PSA_ALG_SIGN_GET_HASH( key_alg2 ) == PSA_ALG_ANY_HASH &&
+ ( alg & ~PSA_ALG_HASH_MASK ) == ( key_alg2 & ~PSA_ALG_HASH_MASK ) )
+ return( 1 );
+ }
+
+ return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
/*
* Helper for mbedtls_pk_sign and mbedtls_pk_verify
*/