Add verify method to HMAC instances to have a comparison utility that does not leak information thr…

tests/lib/crypto/hmac_md5_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Library tag to allow the test to run on Dartium.
 library hmac_md5_test;
 
 import 'dart:crypto';
 
 // Data from http://tools.ietf.org/html/rfc2202.
@@ skipping 53 matching lines @@
             const [ 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
                     0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa ] ];
 
-var hmac_md5_macs =
+var hmac_md5_string_macs =
     const [ '9294727a3638bb1c13f48ef8158bfc9d',
             '750c783e6ab0b503eaa86e310a5db738',
             '56be34521d144c88dbb8c733f0e8b3f6',
             '697eaf0aca3a3aea3a75164746ffaa79',
             '56461ef2342edc00f9bab995690efd4c',
             '6b1ab7fe4bd7bf8f0b62e6ce61b9d0cd',
             '6f630fad67cda0ee1fb1f562db3aa53e' ];
 
-void testStandardVectors(inputs, keys, macs) {
+var hmac_md5_macs =
+    const [ const [0x92, 0x94, 0x72, 0x7a, 0x36, 0x38, 0xbb, 0x1c, 0x13, 0xf4,
+                   0x8e, 0xf8, 0x15, 0x8b, 0xfc, 0x9d],
+            const [0x75, 0x0c, 0x78, 0x3e, 0x6a, 0xb0, 0xb5, 0x03, 0xea, 0xa8,
+                   0x6e, 0x31, 0x0a, 0x5d, 0xb7, 0x38],
+            const [0x56, 0xbe, 0x34, 0x52, 0x1d, 0x14, 0x4c, 0x88, 0xdb, 0xb8,
+                   0xc7, 0x33, 0xf0, 0xe8, 0xb3, 0xf6],
+            const [0x69, 0x7e, 0xaf, 0x0a, 0xca, 0x3a, 0x3a, 0xea, 0x3a, 0x75,
+                   0x16, 0x47, 0x46, 0xff, 0xaa, 0x79],
+            const [0x56, 0x46, 0x1e, 0xf2, 0x34, 0x2e, 0xdc, 0x00, 0xf9, 0xba,
+                   0xb9, 0x95, 0x69, 0x0e, 0xfd, 0x4c],
+            const [0x6b, 0x1a, 0xb7, 0xfe, 0x4b, 0xd7, 0xbf, 0x8f, 0x0b, 0x62,
+                   0xe6, 0xce, 0x61, 0xb9, 0xd0, 0xcd],
+            const [0x6f, 0x63, 0x0f, 0xad, 0x67, 0xcd, 0xa0, 0xee, 0x1f, 0xb1,
+                   0xf5, 0x62, 0xdb, 0x3a, 0xa5, 0x3e]];
+
+void testStandardVectors(inputs, keys, string_macs, macs) {
   for (var i = 0; i < inputs.length; i++) {
-    var d = new HMAC(new MD5(), keys[i]).update(inputs[i]).digest();
-    Expect.isTrue(CryptoUtils.bytesToHex(d).startsWith(macs[i]), '$i');
+    var h = new HMAC(new MD5(), keys[i]);
+    var d = h.update(inputs[i]).digest();
+    Expect.isTrue(CryptoUtils.bytesToHex(d).startsWith(string_macs[i]), '$i');
+    Expect.isTrue(h.verify(macs[i]));
+    Expect.isFalse(h.verify(macs[(i+1)%macs.length]));
+    Expect.throws(() => h.verify([]));
   }
 }
 
 void main() {
-  testStandardVectors(hmac_md5_inputs, hmac_md5_keys, hmac_md5_macs);
+  testStandardVectors(hmac_md5_inputs, hmac_md5_keys,
+                      hmac_md5_string_macs, hmac_md5_macs);
 }