pk: simplify mbedtls_pk_sign_ext()
In case of opaque keys skip the check of the supported primary/enrollment
algorithms. Just try to perfom the signature and if the wrapped key
does not support RSA PSS the operation will fail automatically.
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/pk.c b/library/pk.c
index 097777f..c29318d 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -1327,43 +1327,19 @@
}
if (mbedtls_pk_get_type(ctx) == MBEDTLS_PK_OPAQUE) {
- psa_key_attributes_t key_attr = PSA_KEY_ATTRIBUTES_INIT;
- psa_algorithm_t psa_alg, sign_alg;
-#if defined(MBEDTLS_PSA_CRYPTO_C)
- psa_algorithm_t psa_enrollment_alg;
-#endif /* MBEDTLS_PSA_CRYPTO_C */
psa_status_t status;
- status = psa_get_key_attributes(ctx->priv_id, &key_attr);
- if (status != PSA_SUCCESS) {
- return PSA_PK_RSA_TO_MBEDTLS_ERR(status);
- }
- psa_alg = psa_get_key_algorithm(&key_attr);
-#if defined(MBEDTLS_PSA_CRYPTO_C)
- psa_enrollment_alg = psa_get_key_enrollment_algorithm(&key_attr);
-#endif /* MBEDTLS_PSA_CRYPTO_C */
- psa_reset_key_attributes(&key_attr);
-
- /* Since we're PK type is MBEDTLS_PK_RSASSA_PSS at least one between
- * alg and enrollment alg should be of type RSA_PSS. */
- if (PSA_ALG_IS_RSA_PSS(psa_alg)) {
- sign_alg = psa_alg;
- }
-#if defined(MBEDTLS_PSA_CRYPTO_C)
- else if (PSA_ALG_IS_RSA_PSS(psa_enrollment_alg)) {
- sign_alg = psa_enrollment_alg;
- }
-#endif /* MBEDTLS_PSA_CRYPTO_C */
- else {
- /* The opaque key has no RSA PSS algorithm associated. */
- return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
- }
- /* Adjust the hashing algorithm. */
- sign_alg = (sign_alg & ~PSA_ALG_HASH_MASK) | PSA_ALG_GET_HASH(psa_md_alg);
-
- status = psa_sign_hash(ctx->priv_id, sign_alg,
+ /* PSA_ALG_RSA_PSS() behaves the same as PSA_ALG_RSA_PSS_ANY_SALT() when
+ * performing a signature, but they are encoded differently. Instead of
+ * extracting the proper one from the wrapped key policy, just try both. */
+ status = psa_sign_hash(ctx->priv_id, PSA_ALG_RSA_PSS(psa_md_alg),
hash, hash_len,
sig, sig_size, sig_len);
+ if (status == PSA_ERROR_NOT_PERMITTED) {
+ status = psa_sign_hash(ctx->priv_id, PSA_ALG_RSA_PSS_ANY_SALT(psa_md_alg),
+ hash, hash_len,
+ sig, sig_size, sig_len);
+ }
return PSA_PK_RSA_TO_MBEDTLS_ERR(status);
}