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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "crypto/hmac.h" |
| 6 |
| 7 #include <algorithm> |
| 8 |
| 9 #include "base/logging.h" |
| 10 #include "crypto/secure_util.h" |
| 11 #include "crypto/symmetric_key.h" |
| 12 |
| 13 namespace crypto { |
| 14 |
| 15 bool HMAC::Init(SymmetricKey* key) { |
| 16 std::string raw_key; |
| 17 bool result = key->GetRawKey(&raw_key) && Init(raw_key); |
| 18 // Zero out key copy. This might get optimized away, but one can hope. |
| 19 // Using std::string to store key info at all is a larger problem. |
| 20 std::fill(raw_key.begin(), raw_key.end(), 0); |
| 21 return result; |
| 22 } |
| 23 |
| 24 size_t HMAC::DigestLength() const { |
| 25 switch (hash_alg_) { |
| 26 case SHA1: |
| 27 return 20; |
| 28 case SHA256: |
| 29 return 32; |
| 30 default: |
| 31 NOTREACHED(); |
| 32 return 0; |
| 33 } |
| 34 } |
| 35 |
| 36 bool HMAC::Verify(const base::StringPiece& data, |
| 37 const base::StringPiece& digest) const { |
| 38 if (digest.size() != DigestLength()) |
| 39 return false; |
| 40 return VerifyTruncated(data, digest); |
| 41 } |
| 42 |
| 43 bool HMAC::VerifyTruncated(const base::StringPiece& data, |
| 44 const base::StringPiece& digest) const { |
| 45 if (digest.empty()) |
| 46 return false; |
| 47 size_t digest_length = DigestLength(); |
| 48 scoped_ptr<unsigned char[]> computed_digest( |
| 49 new unsigned char[digest_length]); |
| 50 if (!Sign(data, computed_digest.get(), digest_length)) |
| 51 return false; |
| 52 |
| 53 return SecureMemEqual(digest.data(), computed_digest.get(), |
| 54 std::min(digest.size(), digest_length)); |
| 55 } |
| 56 |
| 57 } // namespace crypto |
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