Implement PBKDF2-based key derivation, random key generation,...

base/crypto/encryptor_win.cc

 // Copyright (c) 2010 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 "base/crypto/encryptor.h"
 
+#include <vector>
+
+#include "base/crypto/symmetric_key.h"
+
 namespace base {
 
-// TODO(albertb): Implement on Windows.
+namespace {
+
+// On success, returns the block size (in bytes) for the algorithm that |key|
+// is for. On failure, returns 0.
+DWORD GetCipherBlockSize(HCRYPTKEY key) {
+  DWORD block_size_in_bits = 0;
+  DWORD param_size = sizeof(block_size_in_bits);
+  BOOL ok = CryptGetKeyParam(key, KP_BLOCKLEN,
+                             reinterpret_cast<BYTE*>(&block_size_in_bits),
+                             &param_size, 0);
+  if (!ok)
+    return 0;
+
+  return block_size_in_bits / 8;
+}
+
+}  // namespace
 
 Encryptor::Encryptor() {
 }
 
 Encryptor::~Encryptor() {
 }
 
 bool Encryptor::Init(SymmetricKey* key, Mode mode, const std::string& iv) {
-  return false;
+  DCHECK(key);
+  DCHECK_EQ(CBC, mode) << "Unsupported mode of operation";
+
+  // In CryptoAPI, the IV, padding mode, and feedback register (for a chaining
+  // mode) are properties of a key, so we have to create a copy of the key for
+  // the Encryptor.  See the Remarks section of the CryptEncrypt MSDN page.
+  BOOL ok = CryptDuplicateKey(key->key(), NULL, 0, capi_key_.receive());
+  if (!ok)
+    return false;
+
+  // CRYPT_MODE_CBC is the default for Microsoft Base Cryptographic Provider,
+  // but we set it anyway to be safe.
+  DWORD cipher_mode = CRYPT_MODE_CBC;
+  ok = CryptSetKeyParam(capi_key_.get(), KP_MODE,
+                        reinterpret_cast<BYTE*>(&cipher_mode), 0);
+  if (!ok)
+    return false;
+
+  block_size_ = GetCipherBlockSize(capi_key_.get());
+  if (block_size_ == 0)
+    return false;
+
+  if (iv.size() != block_size_)
+    return false;
+
+  ok = CryptSetKeyParam(capi_key_.get(), KP_IV,
+                        reinterpret_cast<const BYTE*>(iv.data()), 0);
+  if (!ok)
+    return false;
+
+  DWORD padding_method = PKCS5_PADDING;
+  ok = CryptSetKeyParam(capi_key_.get(), KP_PADDING,
+                        reinterpret_cast<BYTE*>(&padding_method), 0);
+  if (!ok)
+    return false;
+
+  return true;
 }
 
 bool Encryptor::Encrypt(const std::string& plaintext, std::string* ciphertext) {
-  return false;
+  DWORD data_len = plaintext.size();
+  DWORD total_len = data_len + block_size_;
+
+  // CryptoAPI encrypts/decrypts in place.
+  std::vector<BYTE> tmp(total_len);
+  memcpy(&tmp[0], plaintext.data(), data_len);
+
+  BOOL ok = CryptEncrypt(capi_key_.get(), NULL, TRUE, 0, &tmp[0],
+                         &data_len, total_len);
+  if (!ok)
+    return false;
+
+  ciphertext->assign(reinterpret_cast<char*>(&tmp[0]), data_len);
+  return true;
 }
 
 bool Encryptor::Decrypt(const std::string& ciphertext, std::string* plaintext) {
-  return false;
+  DWORD data_len = ciphertext.size();
+
+  std::vector<BYTE> tmp(data_len);
+  memcpy(&tmp[0], ciphertext.data(), data_len);
+
+  BOOL ok = CryptDecrypt(capi_key_.get(), NULL, TRUE, 0, &tmp[0], &data_len);
+  if (!ok)
+    return false;
+
+  DCHECK_GT(tmp.size(), data_len);
+
+  plaintext->assign(reinterpret_cast<char*>(&tmp[0]), data_len);
+  return true;
 }
 
 }  // namespace base