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   CCHmacAlgorithm algorithm;
  46   int algorithm_digest_length;
  47   switch (hash_alg_) {
  48     case SHA1:
  49       algorithm = kCCHmacAlgSHA1;
  50       algorithm_digest_length = CC_SHA1_DIGEST_LENGTH;
  51       break;
  52     case SHA256:
  53       algorithm = kCCHmacAlgSHA256;
  54       algorithm_digest_length = CC_SHA256_DIGEST_LENGTH;
  55       break;
  56     default:
  57       NOTREACHED();
  58       return false;
  59   }
  60
  61   if (digest_length < algorithm_digest_length) {
  62     NOTREACHED();
  63     return false;
  64   }
  65
  66   CCHmac(algorithm,
  67          plat_->key_.data(), plat_->key_.length(), data.data(), data.length(),
  68          digest);
  69
  70   return true;
  71 }
  72
  73 }  // namespace crypto