/*
* Get signature algorithm from alg OID and optional parameters
*/
int mbedtls_x509_get_sig_alg( const mbedtls_x509_buf *sig_oid, const mbedtls_x509_buf *sig_params,
mbedtls_md_type_t *md_alg, mbedtls_pk_type_t *pk_alg,
void **sig_opts )
{
int ret;
if( *sig_opts != NULL )
return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
if( ( ret = mbedtls_oid_get_sig_alg( sig_oid, md_alg, pk_alg ) ) != 0 )
return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG + ret );
#if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
if( *pk_alg == MBEDTLS_PK_RSASSA_PSS )
{
mbedtls_pk_rsassa_pss_options *pss_opts;
pss_opts = mbedtls_calloc( 1, sizeof( mbedtls_pk_rsassa_pss_options ) );
if( pss_opts == NULL )
return( MBEDTLS_ERR_X509_ALLOC_FAILED );
ret = mbedtls_x509_get_rsassa_pss_params( sig_params,
md_alg,
&pss_opts->mgf1_hash_id,
&pss_opts->expected_salt_len );
if( ret != 0 )
{
mbedtls_free( pss_opts );
return( ret );
}
*sig_opts = (void *) pss_opts;
}
else
#endif /* MBEDTLS_X509_RSASSA_PSS_SUPPORT */
{
/* Make sure parameters are absent or NULL */
if( ( sig_params->tag != MBEDTLS_ASN1_NULL && sig_params->tag != 0 ) ||
sig_params->len != 0 )
return( MBEDTLS_ERR_X509_INVALID_ALG );
}
return( 0 );
}
/*
* Verify a signature.
*
* Parameters are passed using the DER encoding format following the ASN.1
* structures detailed above.
*/
static int verify_signature(void *data_ptr, unsigned int data_len,
void *sig_ptr, unsigned int sig_len,
void *sig_alg, unsigned int sig_alg_len,
void *pk_ptr, unsigned int pk_len)
{
mbedtls_asn1_buf sig_oid, sig_params;
mbedtls_asn1_buf signature;
mbedtls_md_type_t md_alg;
mbedtls_pk_type_t pk_alg;
mbedtls_pk_context pk;
int rc;
void *sig_opts = NULL;
const mbedtls_md_info_t *md_info;
unsigned char *p, *end;
unsigned char hash[MBEDTLS_MD_MAX_SIZE];
/* Get pointers to signature OID and parameters */
p = (unsigned char *)sig_alg;
end = (unsigned char *)(p + sig_alg_len);
rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, &sig_params);
if (rc != 0) {
return CRYPTO_ERR_SIGNATURE;
}
/* Get the actual signature algorithm (MD + PK) */
rc = mbedtls_oid_get_sig_alg(&sig_oid, &md_alg, &pk_alg);
if (rc != 0) {
return CRYPTO_ERR_SIGNATURE;
}
/* Parse the public key */
mbedtls_pk_init(&pk);
p = (unsigned char *)pk_ptr;
end = (unsigned char *)(p + pk_len);
rc = mbedtls_pk_parse_subpubkey(&p, end, &pk);
if (rc != 0) {
return CRYPTO_ERR_SIGNATURE;
}
/* Get the signature (bitstring) */
p = (unsigned char *)sig_ptr;
end = (unsigned char *)(p + sig_len);
signature.tag = *p;
rc = mbedtls_asn1_get_bitstring_null(&p, end, &signature.len);
if (rc != 0) {
rc = CRYPTO_ERR_SIGNATURE;
goto end;
}
signature.p = p;
/* Calculate the hash of the data */
md_info = mbedtls_md_info_from_type(md_alg);
if (md_info == NULL) {
rc = CRYPTO_ERR_SIGNATURE;
goto end;
}
p = (unsigned char *)data_ptr;
rc = mbedtls_md(md_info, p, data_len, hash);
if (rc != 0) {
rc = CRYPTO_ERR_SIGNATURE;
goto end;
}
/* Verify the signature */
rc = mbedtls_pk_verify_ext(pk_alg, sig_opts, &pk, md_alg, hash,
mbedtls_md_get_size(md_info),
signature.p, signature.len);
if (rc != 0) {
rc = CRYPTO_ERR_SIGNATURE;
goto end;
}
/* Signature verification success */
rc = CRYPTO_SUCCESS;
end:
mbedtls_pk_free(&pk);
return rc;
}