crypto/hmac_mac.cc

   1 // Copyright (c) 2011 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 <CommonCrypto/CommonHMAC.h>
   8
   9 #include "base/logging.h"
  10
  11 namespace crypto {
  12
  13 struct HMACPlatformData {
  14   std::string key_;
  15 };
  16
  17 HMAC::HMAC(HashAlgorithm hash_alg)
  18     : hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
  19   // Only SHA-1 and SHA-256 hash algorithms are supported now.
  20   DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
  21 }
  22
  23 bool HMAC::Init(const unsigned char *key, int key_length) {
  24   if (!plat_->key_.empty()) {
  25     // Init must not be called more than once on the same HMAC object.
  26     NOTREACHED();
  27     return false;
  28   }
  29
  30   plat_->key_.assign(reinterpret_cast<const char*>(key), key_length);
  31
  32   return true;
  33 }
  34
  35 HMAC::~HMAC() {
  36   // Zero out key copy.
  37   plat_->key_.assign(plat_->key_.length(), std::string::value_type());
  38   plat_->key_.clear();
  39   plat_->key_.reserve(0);
  40 }
  41
  42 bool HMAC::Sign(const base::StringPiece& data,
  43                 unsigned char* digest,
  44                 int digest_length) const {
  45   if (plat_->key_.empty()) {
  46     // Init has not been called or has failed.
  47     NOTREACHED();
  48     return false;
  49   }
  50
  51   CCHmacAlgorithm algorithm;
  52   int algorithm_digest_length;
  53   switch (hash_alg_) {
  54     case SHA1:
  55       algorithm = kCCHmacAlgSHA1;
  56       algorithm_digest_length = CC_SHA1_DIGEST_LENGTH;
  57       break;
  58     case SHA256:
  59       algorithm = kCCHmacAlgSHA256;
  60       algorithm_digest_length = CC_SHA256_DIGEST_LENGTH;
  61       break;
  62     default:
  63       NOTREACHED();
  64       return false;
  65   }
  66
  67   if (digest_length < algorithm_digest_length) {
  68     NOTREACHED();
  69     return false;
  70   }
  71
  72   CCHmac(algorithm,
  73          plat_->key_.data(), plat_->key_.length(), data.data(), data.length(),
  74          digest);
  75
  76   return true;
  77 }
  78
  79 }  // namespace crypto