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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 <cryptohi.h> | |
| 8 #include <stddef.h> | |
| 9 #include <stdint.h> | |
| 10 #include <vector> | |
| 11 | |
| 12 #include "base/logging.h" | |
| 13 #include "crypto/nss_util.h" | |
| 14 #include "crypto/symmetric_key.h" | |
| 15 | |
| 16 namespace crypto { | |
| 17 | |
| 18 namespace { | |
| 19 | |
| 20 inline CK_MECHANISM_TYPE GetMechanism(Encryptor::Mode mode) { | |
| 21 switch (mode) { | |
| 22 case Encryptor::CBC: | |
| 23 return CKM_AES_CBC_PAD; | |
| 24 case Encryptor::CTR: | |
| 25 // AES-CTR encryption uses ECB encryptor as a building block since | |
| 26 // NSS doesn't support CTR encryption mode. | |
| 27 return CKM_AES_ECB; | |
| 28 default: | |
| 29 NOTREACHED() << "Unsupported mode of operation"; | |
| 30 break; | |
| 31 } | |
| 32 return static_cast<CK_MECHANISM_TYPE>(-1); | |
| 33 } | |
| 34 | |
| 35 } // namespace | |
| 36 | |
| 37 Encryptor::Encryptor() | |
| 38 : key_(NULL), | |
| 39 mode_(CBC) { | |
| 40 EnsureNSSInit(); | |
| 41 } | |
| 42 | |
| 43 Encryptor::~Encryptor() { | |
| 44 } | |
| 45 | |
| 46 bool Encryptor::Init(SymmetricKey* key, | |
| 47 Mode mode, | |
| 48 const base::StringPiece& iv) { | |
| 49 DCHECK(key); | |
| 50 DCHECK(CBC == mode || CTR == mode) << "Unsupported mode of operation"; | |
| 51 | |
| 52 key_ = key; | |
| 53 mode_ = mode; | |
| 54 | |
| 55 if (mode == CBC && iv.size() != AES_BLOCK_SIZE) | |
| 56 return false; | |
| 57 | |
| 58 switch (mode) { | |
| 59 case CBC: | |
| 60 SECItem iv_item; | |
| 61 iv_item.type = siBuffer; | |
| 62 iv_item.data = reinterpret_cast<unsigned char*>( | |
| 63 const_cast<char *>(iv.data())); | |
| 64 iv_item.len = iv.size(); | |
| 65 | |
| 66 param_.reset(PK11_ParamFromIV(GetMechanism(mode), &iv_item)); | |
| 67 break; | |
| 68 case CTR: | |
| 69 param_.reset(PK11_ParamFromIV(GetMechanism(mode), NULL)); | |
| 70 break; | |
| 71 } | |
| 72 | |
| 73 return param_ != NULL; | |
| 74 } | |
| 75 | |
| 76 bool Encryptor::Encrypt(const base::StringPiece& plaintext, | |
| 77 std::string* ciphertext) { | |
| 78 CHECK(!plaintext.empty() || (mode_ == CBC)); | |
| 79 ScopedPK11Context context(PK11_CreateContextBySymKey(GetMechanism(mode_), | |
| 80 CKA_ENCRYPT, | |
| 81 key_->key(), | |
| 82 param_.get())); | |
| 83 if (!context.get()) | |
| 84 return false; | |
| 85 | |
| 86 return (mode_ == CTR) ? | |
| 87 CryptCTR(context.get(), plaintext, ciphertext) : | |
| 88 Crypt(context.get(), plaintext, ciphertext); | |
| 89 } | |
| 90 | |
| 91 bool Encryptor::Decrypt(const base::StringPiece& ciphertext, | |
| 92 std::string* plaintext) { | |
| 93 CHECK(!ciphertext.empty()); | |
| 94 ScopedPK11Context context(PK11_CreateContextBySymKey( | |
| 95 GetMechanism(mode_), (mode_ == CTR ? CKA_ENCRYPT : CKA_DECRYPT), | |
| 96 key_->key(), param_.get())); | |
| 97 if (!context.get()) | |
| 98 return false; | |
| 99 | |
| 100 if (mode_ == CTR) | |
| 101 return CryptCTR(context.get(), ciphertext, plaintext); | |
| 102 | |
| 103 if (ciphertext.size() % AES_BLOCK_SIZE != 0) { | |
| 104 // Decryption will fail if the input is not a multiple of the block size. | |
| 105 // PK11_CipherOp has a bug where it will do an invalid memory access before | |
| 106 // the start of the input, so avoid calling it. (NSS bug 922780). | |
| 107 plaintext->clear(); | |
| 108 return false; | |
| 109 } | |
| 110 | |
| 111 return Crypt(context.get(), ciphertext, plaintext); | |
| 112 } | |
| 113 | |
| 114 bool Encryptor::Crypt(PK11Context* context, | |
| 115 const base::StringPiece& input, | |
| 116 std::string* output) { | |
| 117 size_t output_len = input.size() + AES_BLOCK_SIZE; | |
| 118 CHECK_GT(output_len, input.size()); | |
| 119 | |
| 120 output->resize(output_len); | |
| 121 uint8_t* output_data = | |
| 122 reinterpret_cast<uint8_t*>(const_cast<char*>(output->data())); | |
| 123 | |
| 124 int input_len = input.size(); | |
| 125 uint8_t* input_data = | |
| 126 reinterpret_cast<uint8_t*>(const_cast<char*>(input.data())); | |
| 127 | |
| 128 int op_len; | |
| 129 SECStatus rv = PK11_CipherOp(context, | |
| 130 output_data, | |
| 131 &op_len, | |
| 132 output_len, | |
| 133 input_data, | |
| 134 input_len); | |
| 135 | |
| 136 if (SECSuccess != rv) { | |
| 137 output->clear(); | |
| 138 return false; | |
| 139 } | |
| 140 | |
| 141 unsigned int digest_len; | |
| 142 rv = PK11_DigestFinal(context, | |
| 143 output_data + op_len, | |
| 144 &digest_len, | |
| 145 output_len - op_len); | |
| 146 if (SECSuccess != rv) { | |
| 147 output->clear(); | |
| 148 return false; | |
| 149 } | |
| 150 | |
| 151 output->resize(op_len + digest_len); | |
| 152 return true; | |
| 153 } | |
| 154 | |
| 155 bool Encryptor::CryptCTR(PK11Context* context, | |
| 156 const base::StringPiece& input, | |
| 157 std::string* output) { | |
| 158 if (!counter_.get()) { | |
| 159 LOG(ERROR) << "Counter value not set in CTR mode."; | |
| 160 return false; | |
| 161 } | |
| 162 | |
| 163 size_t output_len = ((input.size() + AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE) * | |
| 164 AES_BLOCK_SIZE; | |
| 165 CHECK_GE(output_len, input.size()); | |
| 166 output->resize(output_len); | |
| 167 uint8_t* output_data = | |
| 168 reinterpret_cast<uint8_t*>(const_cast<char*>(output->data())); | |
| 169 | |
| 170 size_t mask_len; | |
| 171 bool ret = GenerateCounterMask(input.size(), output_data, &mask_len); | |
| 172 if (!ret) | |
| 173 return false; | |
| 174 | |
| 175 CHECK_EQ(mask_len, output_len); | |
| 176 int op_len; | |
| 177 SECStatus rv = PK11_CipherOp(context, | |
| 178 output_data, | |
| 179 &op_len, | |
| 180 output_len, | |
| 181 output_data, | |
| 182 mask_len); | |
| 183 if (SECSuccess != rv) | |
| 184 return false; | |
| 185 CHECK_EQ(static_cast<int>(mask_len), op_len); | |
| 186 | |
| 187 unsigned int digest_len; | |
| 188 rv = PK11_DigestFinal(context, | |
| 189 NULL, | |
| 190 &digest_len, | |
| 191 0); | |
| 192 if (SECSuccess != rv) | |
| 193 return false; | |
| 194 CHECK(!digest_len); | |
| 195 | |
| 196 // Use |output_data| to mask |input|. | |
| 197 MaskMessage(reinterpret_cast<uint8_t*>(const_cast<char*>(input.data())), | |
| 198 input.length(), output_data, output_data); | |
| 199 output->resize(input.length()); | |
| 200 return true; | |
| 201 } | |
| 202 | |
| 203 } // namespace crypto | |
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