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/*
* SIV Mode
* (C) 2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_AEAD_SIV_H__
#define BOTAN_AEAD_SIV_H__
#include <botan/aead.h>
#include <botan/block_cipher.h>
#include <botan/stream_cipher.h>
#include <botan/mac.h>
#include <memory>
namespace Botan {
/**
* Base class for SIV encryption and decryption (@see RFC 5297)
*/
class BOTAN_DLL SIV_Mode : public AEAD_Mode
{
public:
secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void set_associated_data_n(size_t n, const byte ad[], size_t ad_len);
void set_associated_data(const byte ad[], size_t ad_len) override
{
set_associated_data_n(0, ad, ad_len);
}
std::string name() const override;
size_t update_granularity() const;
Key_Length_Specification key_spec() const override;
bool valid_nonce_length(size_t) const override;
void clear();
size_t tag_size() const { return 16; }
protected:
SIV_Mode(BlockCipher* cipher);
StreamCipher& ctr() { return *m_ctr; }
void set_ctr_iv(secure_vector<byte> V);
secure_vector<byte>& msg_buf() { return m_msg_buf; }
secure_vector<byte> S2V(const byte text[], size_t text_len);
private:
MessageAuthenticationCode& cmac() { return *m_cmac; }
void key_schedule(const byte key[], size_t length) override;
const std::string m_name;
std::unique_ptr<StreamCipher> m_ctr;
std::unique_ptr<MessageAuthenticationCode> m_cmac;
secure_vector<byte> m_nonce, m_msg_buf;
std::vector<secure_vector<byte>> m_ad_macs;
};
/**
* SIV Encryption
*/
class BOTAN_DLL SIV_Encryption : public SIV_Mode
{
public:
/**
* @param cipher a block cipher
*/
SIV_Encryption(BlockCipher* cipher) : SIV_Mode(cipher) {}
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
size_t output_length(size_t input_length) const override
{ return input_length + tag_size(); }
size_t minimum_final_size() const override { return 0; }
};
/**
* SIV Decryption
*/
class BOTAN_DLL SIV_Decryption : public SIV_Mode
{
public:
/**
* @param cipher a 128-bit block cipher
*/
SIV_Decryption(BlockCipher* cipher) : SIV_Mode(cipher) {}
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
size_t output_length(size_t input_length) const override
{
BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
return input_length - tag_size();
}
size_t minimum_final_size() const override { return tag_size(); }
};
}
#endif
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