Implements encryptor_openssl.cc

base/crypto/encryptor_openssl.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 <openssl/aes.h>
+#include <openssl/evp.h>
+
+#include "base/crypto/symmetric_key.h"
 #include "base/logging.h"
+#include "base/openssl_util.h"
+#include "base/string_util.h"
 
 namespace base {
 
+namespace {
+
+const EVP_CIPHER* GetCipherForKey(SymmetricKey* key) {
+  switch (key->key().length()) {
+    case 16: return EVP_aes_128_cbc();
+    case 24: return EVP_aes_192_cbc();
+    case 32: return EVP_aes_256_cbc();
+    default: return NULL;
+  }
+}
+
+// On destruction this class will cleanup the ctx, and also clear the OpenSSL
+// ERR stack as a convenience.
+class ScopedCipherCTX {
+ public:
+  explicit ScopedCipherCTX() {
+    EVP_CIPHER_CTX_init(&ctx_);
+  }
+  ~ScopedCipherCTX() {
+    EVP_CIPHER_CTX_cleanup(&ctx_);
+    ClearOpenSSLERRStack();
+  }
+  EVP_CIPHER_CTX* get() { return &ctx_; }
+
+ private:
+  EVP_CIPHER_CTX ctx_;
+};
+
+}  // namespace
+
 Encryptor::Encryptor() {
 }
 
 Encryptor::~Encryptor() {
 }
 
 bool Encryptor::Init(SymmetricKey* key, Mode mode, const std::string& iv) {
-  NOTIMPLEMENTED();
-  return false;
+  DCHECK(key);
+  DCHECK_EQ(CBC, mode);
+
+  if (iv.size() != AES_BLOCK_SIZE)
+    return false;
+
+  if (GetCipherForKey(key) == NULL)
+    return false;
+
+  key_ = key;
+  mode_ = mode;
+  iv_ = iv;
+  return true;
 }
 
 bool Encryptor::Encrypt(const std::string& plaintext, std::string* ciphertext) {
-  NOTIMPLEMENTED();
-  return false;
+  return Crypt(true, plaintext, ciphertext);
 }
 
 bool Encryptor::Decrypt(const std::string& ciphertext, std::string* plaintext) {
-  NOTIMPLEMENTED();
-  return false;
+  return Crypt(false, ciphertext, plaintext);
+}
+
+bool Encryptor::Crypt(bool do_encrypt,
+                      const std::string& input,
+                      std::string* output) {
+  // 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->swap(result);
+
+  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), static_cast<int>(iv_.length()));
+  DCHECK_EQ(EVP_CIPHER_key_length(cipher), static_cast<int>(key.length()));
+
+  ScopedCipherCTX ctx;
+  if (!EVP_CipherInit_ex(ctx.get(), cipher, NULL,
+                         reinterpret_cast<const uint8*>(key.data()),
+                         reinterpret_cast<const uint8*>(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);
+  uint8* out_ptr = reinterpret_cast<uint8*>(WriteInto(&result,
+                                                      output_size + 1));
+  int out_len;
+  if (!EVP_CipherUpdate(ctx.get(), out_ptr, &out_len,
+                        reinterpret_cast<const uint8*>(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;
 }
 
 }  // namespace base