Avoid SHA1 weakness

In X509_cmp, if cert digest is equal, look at DER of the
signed part.  This is what master and 1.0.2 already do.

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>

diff --git a/crypto/x509/x509_cmp.c b/crypto/x509/x509_cmp.c
index 3c5b717c15a3551197adda863ecf76907f05f53a..5792e7f51dd2443fcaafbd9b2bd26584a6035f99 100644 (file)
--- a/crypto/x509/x509_cmp.c
+++ b/crypto/x509/x509_cmp.c
@@ -179,11 +179,24 @@ unsigned long X509_subject_name_hash_old(X509 *x)
  */
 int X509_cmp(const X509 *a, const X509 *b)
 {
+    int rv;
+
     /* ensure hash is valid */
     X509_check_purpose((X509 *)a, -1, 0);
     X509_check_purpose((X509 *)b, -1, 0);
 
-    return memcmp(a->sha1_hash, b->sha1_hash, SHA_DIGEST_LENGTH);
+    rv = memcmp(a->sha1_hash, b->sha1_hash, SHA_DIGEST_LENGTH);
+    if (rv)
+        return rv;
+    /* Check for match against stored encoding too */
+    if (!a->cert_info->enc.modified && !b->cert_info->enc.modified) {
+        rv = (int)(a->cert_info->enc.len - b->cert_info->enc.len);
+        if (rv)
+            return rv;
+        return memcmp(a->cert_info->enc.enc, b->cert_info->enc.enc,
+                      a->cert_info->enc.len);
+    }
+    return rv;
 }
 #endif