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/*
* CFB mode
* (C) 1999-2007,2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_MODE_CFB_H__
#define BOTAN_MODE_CFB_H__
#include <botan/cipher_mode.h>
#include <botan/block_cipher.h>
#include <botan/mode_pad.h>
#include <memory>
namespace Botan {
/**
* CFB Mode
*/
class BOTAN_DLL CFB_Mode : public Cipher_Mode
{
public:
secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
std::string name() const override;
size_t update_granularity() const override;
size_t minimum_final_size() const override;
Key_Length_Specification key_spec() const override;
size_t output_length(size_t input_length) const override;
size_t default_nonce_size() const override;
bool valid_nonce_length(size_t n) const override;
void clear();
protected:
CFB_Mode(BlockCipher* cipher, size_t feedback_bits);
const BlockCipher& cipher() const { return *m_cipher; }
size_t feedback() const { return m_feedback_bytes; }
secure_vector<byte>& shift_register() { return m_shift_register; }
secure_vector<byte>& keystream_buf() { return m_keystream_buf; }
private:
void key_schedule(const byte key[], size_t length) override;
std::unique_ptr<BlockCipher> m_cipher;
secure_vector<byte> m_shift_register;
secure_vector<byte> m_keystream_buf;
size_t m_feedback_bytes;
};
/**
* CFB Encryption
*/
class BOTAN_DLL CFB_Encryption : public CFB_Mode
{
public:
CFB_Encryption(BlockCipher* cipher, size_t feedback_bits) :
CFB_Mode(cipher, feedback_bits) {}
void update(secure_vector<byte>& blocks, size_t offset) override;
void finish(secure_vector<byte>& final_block, size_t offset) override;
};
/**
* CFB Decryption
*/
class BOTAN_DLL CFB_Decryption : public CFB_Mode
{
public:
CFB_Decryption(BlockCipher* cipher, size_t feedback_bits) :
CFB_Mode(cipher, feedback_bits) {}
void update(secure_vector<byte>& blocks, size_t offset) override;
void finish(secure_vector<byte>& final_block, size_t offset) override;
};
}
#endif
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