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/*
* SIV Mode
* (C) 2013 Jack Lloyd
* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#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>
namespace Botan {
/**
* Base class for SIV encryption and decryption (@see RFC 5297)
*/
class BOTAN_DLL SIV_Mode : public AEAD_Mode
{
public:
size_t process(uint8_t buf[], size_t size) override;
/**
* Sets the nth element of the vector of associated data
* @param n index into the AD vector
* @param ad associated data
* @param ad_len length of associated data in bytes
*/
void set_associated_data_n(size_t n, const uint8_t ad[], size_t ad_len);
void set_associated_data(const uint8_t ad[], size_t ad_len) override
{
set_associated_data_n(0, ad, ad_len);
}
std::string name() const override;
size_t update_granularity() const override;
Key_Length_Specification key_spec() const override;
bool valid_nonce_length(size_t) const override;
void clear() override;
void reset() override;
size_t tag_size() const override { return 16; }
protected:
explicit SIV_Mode(BlockCipher* cipher);
StreamCipher& ctr() { return *m_ctr; }
void set_ctr_iv(secure_vector<uint8_t> V);
secure_vector<uint8_t>& msg_buf() { return m_msg_buf; }
secure_vector<uint8_t> S2V(const uint8_t text[], size_t text_len);
private:
void start_msg(const uint8_t nonce[], size_t nonce_len) override;
void key_schedule(const uint8_t key[], size_t length) override;
const std::string m_name;
std::unique_ptr<StreamCipher> m_ctr;
std::unique_ptr<MessageAuthenticationCode> m_cmac;
secure_vector<uint8_t> m_nonce, m_msg_buf;
std::vector<secure_vector<uint8_t>> m_ad_macs;
};
/**
* SIV Encryption
*/
class BOTAN_DLL SIV_Encryption final : public SIV_Mode
{
public:
/**
* @param cipher a block cipher
*/
explicit SIV_Encryption(BlockCipher* cipher) : SIV_Mode(cipher) {}
void finish(secure_vector<uint8_t>& 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 final : public SIV_Mode
{
public:
/**
* @param cipher a 128-bit block cipher
*/
explicit SIV_Decryption(BlockCipher* cipher) : SIV_Mode(cipher) {}
void finish(secure_vector<uint8_t>& 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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