crypto/encryptor_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/encryptor.h"
   6
   7 #include <CommonCrypto/CommonCryptor.h>
   8
   9 #include "base/logging.h"
  10 #include "base/string_util.h"
  11 #include "crypto/symmetric_key.h"
  12
  13 namespace crypto {
  14
  15 Encryptor::Encryptor()
  16     : key_(NULL),
  17       mode_(CBC) {
  18 }
  19
  20 Encryptor::~Encryptor() {
  21 }
  22
  23 bool Encryptor::Init(SymmetricKey* key, Mode mode, const std::string& iv) {
  24   DCHECK(key);
  25   DCHECK_EQ(CBC, mode) << "Unsupported mode of operation";
  26   CSSM_DATA raw_key = key->cssm_data();
  27   if (raw_key.Length != kCCKeySizeAES128 &&
  28       raw_key.Length != kCCKeySizeAES192 &&
  29       raw_key.Length != kCCKeySizeAES256)
  30     return false;
  31   if (iv.size() != kCCBlockSizeAES128)
  32     return false;
  33
  34   key_ = key;
  35   mode_ = mode;
  36   iv_ = iv;
  37   return true;
  38 }
  39
  40 bool Encryptor::Crypt(int /*CCOperation*/ op,
  41                       const std::string& input,
  42                       std::string* output) {
  43   DCHECK(key_);
  44   CSSM_DATA raw_key = key_->cssm_data();
  45   // CommonCryptor.h: "A general rule for the size of the output buffer which
  46   // must be provided by the caller is that for block ciphers, the output
  47   // length is never larger than the input length plus the block size."
  48
  49   size_t output_size = input.size() + iv_.size();
  50   CCCryptorStatus err = CCCrypt(op,
  51                                 kCCAlgorithmAES128,
  52                                 kCCOptionPKCS7Padding,
  53                                 raw_key.Data, raw_key.Length,
  54                                 iv_.data(),
  55                                 input.data(), input.size(),
  56                                 WriteInto(output, output_size+1),
  57                                 output_size,
  58                                 &output_size);
  59   if (err) {
  60     output->resize(0);
  61     LOG(ERROR) << "CCCrypt returned " << err;
  62     return false;
  63   }
  64   output->resize(output_size);
  65   return true;
  66 }
  67
  68 bool Encryptor::Encrypt(const std::string& plaintext, std::string* ciphertext) {
  69   return Crypt(kCCEncrypt, plaintext, ciphertext);
  70 }
  71
  72 bool Encryptor::Decrypt(const std::string& ciphertext, std::string* plaintext) {
  73   return Crypt(kCCDecrypt, ciphertext, plaintext);
  74 }
  75
  76 }  // namespace crypto