Add a routine for truncated HMAC verification

crypto/hmac_unittest.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string>
 
 #include "crypto/hmac.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 static const size_t kSHA1DigestSize = 20;
@@ skipping 203 matching lines @@
   ASSERT_TRUE(hmac.Init(kKnownSecretKey, kKnownSecretKeySize));
   unsigned char calculated_hmac[kSHA1DigestSize];
 
   EXPECT_EQ(kSHA1DigestSize, hmac.DigestLength());
   EXPECT_TRUE(hmac.Sign(message_data, calculated_hmac, kSHA1DigestSize));
   EXPECT_EQ(0, memcmp(kKnownHMACSHA1, calculated_hmac, kSHA1DigestSize));
   EXPECT_TRUE(hmac.Verify(
       message_data,
       base::StringPiece(reinterpret_cast<const char*>(kKnownHMACSHA1),
                         kSHA1DigestSize)));
+  EXPECT_TRUE(hmac.VerifyTruncated(
+      message_data,
+      base::StringPiece(reinterpret_cast<const char*>(kKnownHMACSHA1),
+                        kSHA1DigestSize / 2)));
 
   crypto::HMAC hmac2(crypto::HMAC::SHA256);
   ASSERT_TRUE(hmac2.Init(kKnownSecretKey, kKnownSecretKeySize));
   unsigned char calculated_hmac2[kSHA256DigestSize];
 
   EXPECT_TRUE(hmac2.Sign(message_data, calculated_hmac2, kSHA256DigestSize));
   EXPECT_EQ(0, memcmp(kKnownHMACSHA256, calculated_hmac2, kSHA256DigestSize));
 }
 
 TEST(HMACTest, HMACObjectReuse) {
@@ skipping 30 matching lines @@
         base::StringPiece(kSimpleHmacCases[i].data,
                           kSimpleHmacCases[i].data_len)));
 
     // Expected size, mismatched data
     EXPECT_FALSE(hmac.Verify(
         base::StringPiece(kSimpleHmacCases[i].data,
                           kSimpleHmacCases[i].data_len),
         base::StringPiece(empty_digest, kSHA1DigestSize)));
   }
 }