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      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
     77