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/*
* SHAKE-128 and SHAKE-256 as a stream ciphers
* (C) 2016 Jack Lloyd
* 2022 René Meusel, Michael Boric - Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_SHAKE_CIPHER_H_
#define BOTAN_SHAKE_CIPHER_H_
#include <botan/stream_cipher.h>
#include <botan/internal/keccak_perm.h>
namespace Botan {
/**
* Base class for SHAKE-based XOFs presented as a stream cipher
*/
class SHAKE_Cipher : public StreamCipher {
protected:
explicit SHAKE_Cipher(size_t keccak_capacity);
public:
/**
* Seeking is not supported, this function will throw
*/
void seek(uint64_t offset) final;
void clear() final;
Key_Length_Specification key_spec() const final;
bool has_keying_material() const final { return m_has_keying_material; }
size_t buffer_size() const final { return m_keccak.byte_rate(); }
private:
void key_schedule(std::span<const uint8_t> key) final;
/**
* Produce more XOF output
*/
void cipher_bytes(const uint8_t in[], uint8_t out[], size_t length) final;
void generate_keystream(uint8_t out[], size_t length) override;
void generate_keystream_internal(std::span<uint8_t> out);
/**
* IV not supported, this function will throw unless iv_len == 0
*/
void set_iv_bytes(const uint8_t iv[], size_t iv_len) final;
private:
Keccak_Permutation m_keccak;
bool m_has_keying_material;
secure_vector<uint8_t> m_keystream_buffer;
size_t m_bytes_generated;
};
class SHAKE_128_Cipher final : public SHAKE_Cipher {
public:
SHAKE_128_Cipher();
std::string name() const override { return "SHAKE-128"; }
std::unique_ptr<StreamCipher> new_object() const override { return std::make_unique<SHAKE_128_Cipher>(); }
};
class SHAKE_256_Cipher final : public SHAKE_Cipher {
public:
SHAKE_256_Cipher();
std::string name() const override { return "SHAKE-256"; }
std::unique_ptr<StreamCipher> new_object() const override { return std::make_unique<SHAKE_256_Cipher>(); }
};
} // namespace Botan
#endif