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/*
* CBC mode
* (C) 1999-2007,2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_MODE_CBC_H__
#define BOTAN_MODE_CBC_H__
#include <botan/transform.h>
#include <botan/block_cipher.h>
#include <botan/mode_pad.h>
#include <memory>
namespace Botan {
/**
* CBC Mode
*/
class CBC_Mode : public Transformation
{
public:
secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
std::string name() const override;
size_t update_granularity() const override;
Key_Length_Specification key_spec() const override;
size_t default_nonce_size() const override;
bool valid_nonce_length(size_t n) const override;
void clear();
protected:
CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding);
const BlockCipher& cipher() const { return *m_cipher; }
const BlockCipherModePaddingMethod& padding() const
{
BOTAN_ASSERT_NONNULL(m_padding);
return *m_padding;
}
secure_vector<byte>& state() { return m_state; }
byte* state_ptr() { return &m_state[0]; }
private:
void key_schedule(const byte key[], size_t length) override;
std::unique_ptr<BlockCipher> m_cipher;
std::unique_ptr<BlockCipherModePaddingMethod> m_padding;
secure_vector<byte> m_state;
};
/**
* CBC Encryption
*/
class BOTAN_DLL CBC_Encryption : public CBC_Mode
{
public:
CBC_Encryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
CBC_Mode(cipher, padding) {}
void update(secure_vector<byte>& blocks, size_t offset) override;
void finish(secure_vector<byte>& final_block, size_t offset) override;
size_t output_length(size_t input_length) const override;
size_t minimum_final_size() const override;
};
/**
* CBC Encryption with ciphertext stealing (CBC-CS3 variant)
*/
class BOTAN_DLL CTS_Encryption : public CBC_Encryption
{
public:
CTS_Encryption(BlockCipher* cipher) : CBC_Encryption(cipher, nullptr) {}
size_t output_length(size_t input_length) const override;
void finish(secure_vector<byte>& final_block, size_t offset) override;
size_t minimum_final_size() const override;
bool valid_nonce_length(size_t n) const;
};
/**
* CBC Decryption
*/
class BOTAN_DLL CBC_Decryption : public CBC_Mode
{
public:
CBC_Decryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
CBC_Mode(cipher, padding), m_tempbuf(update_granularity()) {}
void update(secure_vector<byte>& blocks, size_t offset) override;
void finish(secure_vector<byte>& final_block, size_t offset) override;
size_t output_length(size_t input_length) const override;
size_t minimum_final_size() const override;
private:
secure_vector<byte> m_tempbuf;
};
/**
* CBC Decryption with ciphertext stealing (CBC-CS3 variant)
*/
class BOTAN_DLL CTS_Decryption : public CBC_Decryption
{
public:
CTS_Decryption(BlockCipher* cipher) : CBC_Decryption(cipher, nullptr) {}
void finish(secure_vector<byte>& final_block, size_t offset) override;
size_t minimum_final_size() const override;
bool valid_nonce_length(size_t n) const;
};
}
#endif
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