components/webcrypto/algorithms/aes_cbc.cc

   1 // Copyright 2014 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 <openssl/aes.h>
   6 #include <openssl/evp.h>
   7
   8 #include "base/logging.h"
   9 #include "base/numerics/safe_math.h"
  10 #include "base/stl_util.h"
  11 #include "components/webcrypto/algorithms/aes.h"
  12 #include "components/webcrypto/algorithms/util_openssl.h"
  13 #include "components/webcrypto/crypto_data.h"
  14 #include "components/webcrypto/key.h"
  15 #include "components/webcrypto/status.h"
  16 #include "components/webcrypto/webcrypto_util.h"
  17 #include "crypto/openssl_util.h"
  18 #include "crypto/scoped_openssl_types.h"
  19 #include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
  20
  21 namespace webcrypto {
  22
  23 namespace {
  24
  25 const EVP_CIPHER* GetAESCipherByKeyLength(size_t key_length_bytes) {
  26   // BoringSSL does not support 192-bit AES keys.
  27   switch (key_length_bytes) {
  28     case 16:
  29       return EVP_aes_128_cbc();
  30     case 32:
  31       return EVP_aes_256_cbc();
  32     default:
  33       return NULL;
  34   }
  35 }
  36
  37 Status AesCbcEncryptDecrypt(EncryptOrDecrypt cipher_operation,
  38                             const blink::WebCryptoAlgorithm& algorithm,
  39                             const blink::WebCryptoKey& key,
  40                             const CryptoData& data,
  41                             std::vector<uint8_t>* buffer) {
  42   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
  43
  44   const blink::WebCryptoAesCbcParams* params = algorithm.aesCbcParams();
  45   const std::vector<uint8_t>& raw_key = GetSymmetricKeyData(key);
  46
  47   if (params->iv().size() != 16)
  48     return Status::ErrorIncorrectSizeAesCbcIv();
  49
  50   // According to the openssl docs, the amount of data written may be as large
  51   // as (data_size + cipher_block_size - 1), constrained to a multiple of
  52   // cipher_block_size.
  53   base::CheckedNumeric<int> output_max_len = data.byte_length();
  54   output_max_len += AES_BLOCK_SIZE - 1;
  55   if (!output_max_len.IsValid())
  56     return Status::ErrorDataTooLarge();
  57
  58   const unsigned remainder = output_max_len.ValueOrDie() % AES_BLOCK_SIZE;
  59   if (remainder != 0)
  60     output_max_len += AES_BLOCK_SIZE - remainder;
  61   if (!output_max_len.IsValid())
  62     return Status::ErrorDataTooLarge();
  63
  64   // Note: PKCS padding is enabled by default
  65   crypto::ScopedOpenSSL<EVP_CIPHER_CTX, EVP_CIPHER_CTX_free> context(
  66       EVP_CIPHER_CTX_new());
  67
  68   if (!context.get())
  69     return Status::OperationError();
  70
  71   const EVP_CIPHER* const cipher = GetAESCipherByKeyLength(raw_key.size());
  72   DCHECK(cipher);
  73
  74   if (!EVP_CipherInit_ex(context.get(), cipher, NULL, &raw_key[0],
  75                          params->iv().data(), cipher_operation)) {
  76     return Status::OperationError();
  77   }
  78
  79   buffer->resize(output_max_len.ValueOrDie());
  80
  81   unsigned char* const buffer_data = vector_as_array(buffer);
  82
  83   int output_len = 0;
  84   if (!EVP_CipherUpdate(context.get(), buffer_data, &output_len, data.bytes(),
  85                         data.byte_length())) {
  86     return Status::OperationError();
  87   }
  88   int final_output_chunk_len = 0;
  89   if (!EVP_CipherFinal_ex(context.get(), buffer_data + output_len,
  90                           &final_output_chunk_len)) {
  91     return Status::OperationError();
  92   }
  93
  94   const unsigned int final_output_len =
  95       static_cast<unsigned int>(output_len) +
  96       static_cast<unsigned int>(final_output_chunk_len);
  97
  98   buffer->resize(final_output_len);
  99
 100   return Status::Success();
 101 }
 102
 103 class AesCbcImplementation : public AesAlgorithm {
 104  public:
 105   AesCbcImplementation() : AesAlgorithm("CBC") {}
 106
 107   Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
 108                  const blink::WebCryptoKey& key,
 109                  const CryptoData& data,
 110                  std::vector<uint8_t>* buffer) const override {
 111     return AesCbcEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
 112   }
 113
 114   Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
 115                  const blink::WebCryptoKey& key,
 116                  const CryptoData& data,
 117                  std::vector<uint8_t>* buffer) const override {
 118     return AesCbcEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
 119   }
 120 };
 121
 122 }  // namespace
 123
 124 scoped_ptr<AlgorithmImplementation> CreateAesCbcImplementation() {
 125   return make_scoped_ptr(new AesCbcImplementation);
 126 }
 127
 128 }  // namespace webcrypto