Restrict MD5 in x509 certificates
Remove support for X509 certificates signed with MD5.
Issue raised by Harm Verhagen
diff --git a/library/x509_crt.c b/library/x509_crt.c
index a3517f6..186ecda 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1434,6 +1434,18 @@
return( (int) ( size - n ) );
}
+/*
+ * Check md_alg against profile
+ * Return 0 if md_alg acceptable for this profile, -1 otherwise
+ */
+static int x509_check_md_alg( md_type_t md_alg )
+{
+ if( md_alg >= POLARSSL_MINIMAL_SUPPORTED_MD_ALG )
+ return( 0 );
+
+ return( -1 );
+}
+
#if defined(POLARSSL_X509_CHECK_KEY_USAGE)
int x509_crt_check_key_usage( const x509_crt *crt, int usage )
{
@@ -1542,6 +1554,15 @@
#endif
/*
+ * Check if CRL is signed with a valid MD
+ */
+ if( x509_check_md_alg( crl_list->sig_md ) != 0 )
+ {
+ flags |= BADCRL_NOT_TRUSTED;
+ break;
+ }
+
+ /*
* Check if CRL is correctly signed by the trusted CA
*/
md_info = md_info_from_type( crl_list->sig_md );
@@ -1788,6 +1809,18 @@
*/
*flags |= BADCERT_NOT_TRUSTED;
+ /*
+ * Check if certificate is signed with a valid MD
+ */
+ if( x509_check_md_alg( child->sig_md ) != 0 )
+ {
+ *flags |= BADCERT_NOT_TRUSTED;
+ /*
+ * not signed with a valid MD, no need to check trust_ca
+ */
+ trust_ca = NULL;
+ }
+
md_info = md_info_from_type( child->sig_md );
if( md_info == NULL )
{
@@ -1925,6 +1958,12 @@
if( x509_time_future( &child->valid_from ) )
*flags |= BADCERT_FUTURE;
+ /*
+ * Check if certificate is signed with a valid MD
+ */
+ if( x509_check_md_alg( child->sig_md ) != 0 )
+ *flags |= BADCERT_NOT_TRUSTED;
+
md_info = md_info_from_type( child->sig_md );
if( md_info == NULL )
{