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 <stddef.h> 8 9 #include <algorithm> 10 11 #include "base/logging.h" 12 #include "crypto/secure_util.h" 13 #include "crypto/symmetric_key.h" 14 15 namespace crypto { 16 17 bool HMAC::Init(SymmetricKey* key) { 18 std::string raw_key; 19 bool result = key->GetRawKey(&raw_key) && Init(raw_key); 20 // Zero out key copy. This might get optimized away, but one can hope. 21 // Using std::string to store key info at all is a larger problem. 22 std::fill(raw_key.begin(), raw_key.end(), 0); 23 return result; 24 } 25 26 size_t HMAC::DigestLength() const { 27 switch (hash_alg_) { 28 case SHA1: 29 return 20; 30 case SHA256: 31 return 32; 32 default: 33 NOTREACHED(); 34 return 0; 35 } 36 } 37 38 bool HMAC::Verify(const base::StringPiece& data, 39 const base::StringPiece& digest) const { 40 if (digest.size() != DigestLength()) 41 return false; 42 return VerifyTruncated(data, digest); 43 } 44 45 bool HMAC::VerifyTruncated(const base::StringPiece& data, 46 const base::StringPiece& digest) const { 47 if (digest.empty()) 48 return false; 49 size_t digest_length = DigestLength(); 50 std::unique_ptr<unsigned char[]> computed_digest( 51 new unsigned char[digest_length]); 52 if (!Sign(data, computed_digest.get(), digest_length)) 53 return false; 54 55 return SecureMemEqual(digest.data(), computed_digest.get(), 56 std::min(digest.size(), digest_length)); 57 } 58 59 } // namespace crypto 60
