crypto/hmac_openssl.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 <openssl/hmac.h>
   8
   9 #include <algorithm>
  10 #include <vector>
  11
  12 #include "base/logging.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/stl_util.h"
  15 #include "crypto/openssl_util.h"
  16
  17 namespace crypto {
  18
  19 struct HMACPlatformData {
  20   std::vector<unsigned char> key;
  21 };
  22
  23 HMAC::HMAC(HashAlgorithm hash_alg) : hash_alg_(hash_alg) {
  24   // Only SHA-1 and SHA-256 hash algorithms are supported now.
  25   DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
  26 }
  27
  28 bool HMAC::Init(const unsigned char* key, size_t key_length) {
  29   // Init must not be called more than once on the same HMAC object.
  30   DCHECK(!plat_);
  31   plat_.reset(new HMACPlatformData());
  32   plat_->key.assign(key, key + key_length);
  33   return true;
  34 }
  35
  36 HMAC::~HMAC() {
  37   if (plat_) {
  38     // Zero out key copy.
  39     plat_->key.assign(plat_->key.size(), 0);
  40     STLClearObject(&plat_->key);
  41   }
  42 }
  43
  44 bool HMAC::Sign(const base::StringPiece& data,
  45                 unsigned char* digest,
  46                 size_t digest_length) const {
  47   DCHECK(plat_);  // Init must be called before Sign.
  48
  49   ScopedOpenSSLSafeSizeBuffer<EVP_MAX_MD_SIZE> result(digest, digest_length);
  50   return !!::HMAC(hash_alg_ == SHA1 ? EVP_sha1() : EVP_sha256(),
  51                   vector_as_array(&plat_->key), plat_->key.size(),
  52                   reinterpret_cast<const unsigned char*>(data.data()),
  53                   data.size(), result.safe_buffer(), NULL);
  54 }
  55
  56 }  // namespace crypto