| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "crypto/encryptor.h" |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include "base/logging.h" |
| #include "base/strings/string_util.h" |
| #include "base/sys_byteorder.h" |
| #include "crypto/openssl_util.h" |
| #include "crypto/symmetric_key.h" |
| #include "third_party/boringssl/src/include/openssl/aes.h" |
| #include "third_party/boringssl/src/include/openssl/evp.h" |
| |
| namespace crypto { |
| |
| namespace { |
| |
| const EVP_CIPHER* GetCipherForKey(const SymmetricKey* key) { |
| switch (key->key().length()) { |
| case 16: return EVP_aes_128_cbc(); |
| case 32: return EVP_aes_256_cbc(); |
| default: |
| return nullptr; |
| } |
| } |
| |
| // On destruction this class will cleanup the ctx, and also clear the OpenSSL |
| // ERR stack as a convenience. |
| class ScopedCipherCTX { |
| public: |
| ScopedCipherCTX() { |
| EVP_CIPHER_CTX_init(&ctx_); |
| } |
| ~ScopedCipherCTX() { |
| EVP_CIPHER_CTX_cleanup(&ctx_); |
| ClearOpenSSLERRStack(FROM_HERE); |
| } |
| EVP_CIPHER_CTX* get() { return &ctx_; } |
| |
| private: |
| EVP_CIPHER_CTX ctx_; |
| }; |
| |
| } // namespace |
| |
| ///////////////////////////////////////////////////////////////////////////// |
| // Encyptor::Counter Implementation. |
| Encryptor::Counter::Counter(base::StringPiece counter) { |
| CHECK(sizeof(counter_) == counter.length()); |
| |
| memcpy(&counter_, counter.data(), sizeof(counter_)); |
| } |
| |
| Encryptor::Counter::~Counter() { |
| } |
| |
| bool Encryptor::Counter::Increment() { |
| uint64_t low_num = base::NetToHost64(counter_.components64[1]); |
| uint64_t new_low_num = low_num + 1; |
| counter_.components64[1] = base::HostToNet64(new_low_num); |
| |
| // If overflow occured then increment the most significant component. |
| if (new_low_num < low_num) { |
| counter_.components64[0] = |
| base::HostToNet64(base::NetToHost64(counter_.components64[0]) + 1); |
| } |
| |
| // TODO(hclam): Return false if counter value overflows. |
| return true; |
| } |
| |
| void Encryptor::Counter::Write(void* buf) { |
| uint8_t* buf_ptr = reinterpret_cast<uint8_t*>(buf); |
| memcpy(buf_ptr, &counter_, sizeof(counter_)); |
| } |
| |
| size_t Encryptor::Counter::GetLengthInBytes() const { |
| return sizeof(counter_); |
| } |
| |
| ///////////////////////////////////////////////////////////////////////////// |
| // Encryptor Implementation. |
| |
| Encryptor::Encryptor() : key_(nullptr), mode_(CBC) {} |
| |
| Encryptor::~Encryptor() { |
| } |
| |
| bool Encryptor::Init(const SymmetricKey* key, Mode mode, base::StringPiece iv) { |
| DCHECK(key); |
| DCHECK(mode == CBC || mode == CTR); |
| |
| EnsureOpenSSLInit(); |
| if (mode == CBC && iv.size() != AES_BLOCK_SIZE) |
| return false; |
| |
| if (GetCipherForKey(key) == nullptr) |
| return false; |
| |
| key_ = key; |
| mode_ = mode; |
| iv.CopyToString(&iv_); |
| return true; |
| } |
| |
| bool Encryptor::Encrypt(base::StringPiece plaintext, std::string* ciphertext) { |
| CHECK(!plaintext.empty() || (mode_ == CBC)); |
| return (mode_ == CTR) ? |
| CryptCTR(true, plaintext, ciphertext) : |
| Crypt(true, plaintext, ciphertext); |
| } |
| |
| bool Encryptor::Decrypt(base::StringPiece ciphertext, std::string* plaintext) { |
| CHECK(!ciphertext.empty()); |
| return (mode_ == CTR) ? |
| CryptCTR(false, ciphertext, plaintext) : |
| Crypt(false, ciphertext, plaintext); |
| } |
| |
| bool Encryptor::SetCounter(base::StringPiece counter) { |
| if (mode_ != CTR) |
| return false; |
| if (counter.length() != 16u) |
| return false; |
| |
| counter_.reset(new Counter(counter)); |
| return true; |
| } |
| |
| bool Encryptor::Crypt(bool do_encrypt, |
| base::StringPiece input, |
| std::string* output) { |
| DCHECK(key_); // Must call Init() before En/De-crypt. |
| // Work on the result in a local variable, and then only transfer it to |
| // |output| on success to ensure no partial data is returned. |
| std::string result; |
| output->clear(); |
| |
| const EVP_CIPHER* cipher = GetCipherForKey(key_); |
| DCHECK(cipher); // Already handled in Init(); |
| |
| const std::string& key = key_->key(); |
| DCHECK_EQ(EVP_CIPHER_iv_length(cipher), iv_.length()); |
| DCHECK_EQ(EVP_CIPHER_key_length(cipher), key.length()); |
| |
| ScopedCipherCTX ctx; |
| if (!EVP_CipherInit_ex(ctx.get(), cipher, nullptr, |
| reinterpret_cast<const uint8_t*>(key.data()), |
| reinterpret_cast<const uint8_t*>(iv_.data()), |
| do_encrypt)) |
| return false; |
| |
| // When encrypting, add another block size of space to allow for any padding. |
| const size_t output_size = input.size() + (do_encrypt ? iv_.size() : 0); |
| CHECK_GT(output_size, 0u); |
| CHECK_GT(output_size + 1, input.size()); |
| uint8_t* out_ptr = |
| reinterpret_cast<uint8_t*>(base::WriteInto(&result, output_size + 1)); |
| int out_len; |
| if (!EVP_CipherUpdate(ctx.get(), out_ptr, &out_len, |
| reinterpret_cast<const uint8_t*>(input.data()), |
| input.length())) |
| return false; |
| |
| // Write out the final block plus padding (if any) to the end of the data |
| // just written. |
| int tail_len; |
| if (!EVP_CipherFinal_ex(ctx.get(), out_ptr + out_len, &tail_len)) |
| return false; |
| |
| out_len += tail_len; |
| DCHECK_LE(out_len, static_cast<int>(output_size)); |
| result.resize(out_len); |
| |
| output->swap(result); |
| return true; |
| } |
| |
| bool Encryptor::CryptCTR(bool do_encrypt, |
| base::StringPiece input, |
| std::string* output) { |
| if (!counter_.get()) { |
| LOG(ERROR) << "Counter value not set in CTR mode."; |
| return false; |
| } |
| |
| AES_KEY aes_key; |
| if (AES_set_encrypt_key(reinterpret_cast<const uint8_t*>(key_->key().data()), |
| key_->key().size() * 8, &aes_key) != 0) { |
| return false; |
| } |
| |
| const size_t out_size = input.size(); |
| CHECK_GT(out_size, 0u); |
| CHECK_GT(out_size + 1, input.size()); |
| |
| std::string result; |
| uint8_t* out_ptr = |
| reinterpret_cast<uint8_t*>(base::WriteInto(&result, out_size + 1)); |
| |
| uint8_t ivec[AES_BLOCK_SIZE] = { 0 }; |
| uint8_t ecount_buf[AES_BLOCK_SIZE] = { 0 }; |
| unsigned int block_offset = 0; |
| |
| counter_->Write(ivec); |
| |
| AES_ctr128_encrypt(reinterpret_cast<const uint8_t*>(input.data()), out_ptr, |
| input.size(), &aes_key, ivec, ecount_buf, &block_offset); |
| |
| // AES_ctr128_encrypt() updates |ivec|. Update the |counter_| here. |
| SetCounter(base::StringPiece(reinterpret_cast<const char*>(ivec), |
| AES_BLOCK_SIZE)); |
| |
| output->swap(result); |
| return true; |
| } |
| |
| } // namespace crypto |