/*

 * 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/secmem.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 shake_rate);

   public:

      /**

      * Produce more XOF output

      */

      void cipher(const uint8_t in[], uint8_t out[], size_t length) override final;

      void write_keystream(uint8_t out[], size_t length) override;

      /**

      * Seeking is not supported, this function will throw

      */

      void seek(uint64_t offset) override final;

      /**

      * IV not supported, this function will throw unless iv_len == 0

      */

      void set_iv(const uint8_t iv[], size_t iv_len) override final;

      void clear() override final;

      Key_Length_Specification key_spec() const override final;

   private:

      void key_schedule(const uint8_t key[], size_t key_len) override final;

   protected:

      size_t m_shake_rate;

      secure_vector<uint64_t> m_state; // internal state

      secure_vector<uint8_t> m_buffer; // ciphertext buffer

      size_t m_buf_pos; // position in m_buffer

   };

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>(); }

   };

}

#endif