components/webcrypto/algorithms/aes_gcm.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/evp.h>
   6 #include <vector>
   7
   8 #include "base/logging.h"
   9 #include "base/stl_util.h"
  10 #include "components/webcrypto/algorithms/aes.h"
  11 #include "components/webcrypto/algorithms/util_openssl.h"
  12 #include "components/webcrypto/crypto_data.h"
  13 #include "components/webcrypto/key.h"
  14 #include "components/webcrypto/status.h"
  15 #include "components/webcrypto/webcrypto_util.h"
  16 #include "crypto/openssl_util.h"
  17 #include "crypto/scoped_openssl_types.h"
  18 #include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
  19
  20 namespace webcrypto {
  21
  22 namespace {
  23
  24 const EVP_AEAD* GetAesGcmAlgorithmFromKeySize(size_t key_size_bytes) {
  25   switch (key_size_bytes) {
  26     case 16:
  27       return EVP_aead_aes_128_gcm();
  28     case 32:
  29       return EVP_aead_aes_256_gcm();
  30     default:
  31       return NULL;
  32   }
  33 }
  34
  35 Status AesGcmEncryptDecrypt(EncryptOrDecrypt mode,
  36                             const blink::WebCryptoAlgorithm& algorithm,
  37                             const blink::WebCryptoKey& key,
  38                             const CryptoData& data,
  39                             std::vector<uint8_t>* buffer) {
  40   const std::vector<uint8_t>& raw_key = GetSymmetricKeyData(key);
  41   const blink::WebCryptoAesGcmParams* params = algorithm.aesGcmParams();
  42
  43   // The WebCrypto spec defines the default value for the tag length, as well as
  44   // the allowed values for tag length.
  45   unsigned int tag_length_bits = 128;
  46   if (params->hasTagLengthBits()) {
  47     tag_length_bits = params->optionalTagLengthBits();
  48     if (tag_length_bits != 32 && tag_length_bits != 64 &&
  49         tag_length_bits != 96 && tag_length_bits != 104 &&
  50         tag_length_bits != 112 && tag_length_bits != 120 &&
  51         tag_length_bits != 128) {
  52       return Status::ErrorInvalidAesGcmTagLength();
  53     }
  54   }
  55
  56   return AeadEncryptDecrypt(
  57       mode, raw_key, data, tag_length_bits / 8, CryptoData(params->iv()),
  58       CryptoData(params->optionalAdditionalData()),
  59       GetAesGcmAlgorithmFromKeySize(raw_key.size()), buffer);
  60 }
  61
  62 class AesGcmImplementation : public AesAlgorithm {
  63  public:
  64   AesGcmImplementation() : AesAlgorithm("GCM") {}
  65
  66   Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
  67                  const blink::WebCryptoKey& key,
  68                  const CryptoData& data,
  69                  std::vector<uint8_t>* buffer) const override {
  70     return AesGcmEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
  71   }
  72
  73   Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
  74                  const blink::WebCryptoKey& key,
  75                  const CryptoData& data,
  76                  std::vector<uint8_t>* buffer) const override {
  77     return AesGcmEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
  78   }
  79 };
  80
  81 }  // namespace
  82
  83 scoped_ptr<AlgorithmImplementation> CreateAesGcmImplementation() {
  84   return make_scoped_ptr(new AesGcmImplementation);
  85 }
  86
  87 }  // namespace webcrypto