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// Copyright (c) 2011 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.
#ifndef CRYPTO_ENCRYPTOR_H_
#define CRYPTO_ENCRYPTOR_H_
#pragma once
#include <string>
#include "base/basictypes.h"
#include "base/scoped_ptr.h"
#include "build/build_config.h"
#include "crypto/crypto_api.h"
#if defined(USE_NSS)
#include "crypto/scoped_nss_types.h"
#elif defined(OS_WIN)
#include "crypto/scoped_capi_types.h"
#endif
namespace crypto {
class SymmetricKey;
class CRYPTO_API Encryptor {
public:
enum Mode {
CBC,
CTR,
};
// This class implements a 128-bits counter to be used in AES-CTR encryption.
// Only 128-bits counter is supported in this class.
class Counter {
public:
Counter(const std::string& counter);
~Counter();
// Increment the counter value.
bool Increment();
// Write the content of the counter to |buf|. |buf| should have enough
// space for |GetLengthInBytes()|.
void Write(void* buf);
// Return the length of this counter.
size_t GetLengthInBytes() const;
private:
union {
uint32 components32[4];
uint64 components64[2];
} counter_;
};
Encryptor();
virtual ~Encryptor();
// Initializes the encryptor using |key| and |iv|. Returns false if either the
// key or the initialization vector cannot be used.
//
// When |mode| is CTR then |iv| should be empty.
bool Init(SymmetricKey* key, Mode mode, const std::string& iv);
// Encrypts |plaintext| into |ciphertext|.
bool Encrypt(const std::string& plaintext, std::string* ciphertext);
// Decrypts |ciphertext| into |plaintext|.
bool Decrypt(const std::string& ciphertext, std::string* plaintext);
// Sets the counter value when in CTR mode. Currently only 128-bits
// counter value is supported.
//
// Returns true only if update was successful.
bool SetCounter(const std::string& counter);
// TODO(albertb): Support streaming encryption.
private:
// Generates a mask using |counter_| to be used for encryption in CTR mode.
// Resulting mask will be written to |mask| with |mask_len| bytes.
//
// Make sure there's enough space in mask when calling this method.
// Reserve at least |plaintext_len| + 16 bytes for |mask|.
//
// The generated mask will always have at least |plaintext_len| bytes and
// will be a multiple of the counter length.
//
// This method is used only in CTR mode.
//
// Returns false if this call failed.
bool GenerateCounterMask(size_t plaintext_len,
uint8* mask,
size_t* mask_len);
// Mask the |plaintext| message using |mask|. The output will be written to
// |ciphertext|. |ciphertext| must have at least |plaintext_len| bytes.
void MaskMessage(const void* plaintext,
size_t plaintext_len,
const void* mask,
void* ciphertext) const;
SymmetricKey* key_;
Mode mode_;
scoped_ptr<Counter> counter_;
#if defined(USE_OPENSSL)
bool Crypt(bool encrypt, // Pass true to encrypt, false to decrypt.
const std::string& input,
std::string* output);
std::string iv_;
#elif defined(USE_NSS)
bool Crypt(PK11Context* context,
const std::string& input,
std::string* output);
bool CryptCTR(PK11Context* context,
const std::string& input,
std::string* output);
ScopedPK11Slot slot_;
ScopedSECItem param_;
#elif defined(OS_MACOSX)
bool Crypt(int /*CCOperation*/ op,
const std::string& input,
std::string* output);
std::string iv_;
#elif defined(OS_WIN)
ScopedHCRYPTKEY capi_key_;
DWORD block_size_;
#endif
};
} // namespace crypto
#endif // CRYPTO_ENCRYPTOR_H_
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