/*

* The Skein-512 hash function

* (C) 2009,2014 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#ifndef BOTAN_SKEIN_512_H_

#define BOTAN_SKEIN_512_H_

#include <botan/hash.h>

#include <botan/internal/threefish_512.h>

#include <string>

#include <memory>

namespace Botan {

/**

* Skein-512, a SHA-3 candidate

*/

class Skein_512 final : public HashFunction

   {

   public:

      /**

      * @param output_bits the output size of Skein in bits

      * @param personalization is a string that will parameterize the

      * hash output

      */

      Skein_512(size_t output_bits = 512,

                const std::string& personalization = "");

      size_t hash_block_size() const override { return 64; }

      size_t output_length() const override { return m_output_bits / 8; }

      std::unique_ptr<HashFunction> new_object() const override;

      std::unique_ptr<HashFunction> copy_state() const override;

      std::string name() const override;

      void clear() override;

   private:

      enum type_code {

         SKEIN_KEY = 0,

         SKEIN_CONFIG = 4,

         SKEIN_PERSONALIZATION = 8,

         SKEIN_PUBLIC_KEY = 12,

         SKEIN_KEY_IDENTIFIER = 16,

         SKEIN_NONCE = 20,

         SKEIN_MSG = 48,

         SKEIN_OUTPUT = 63

      };

      void add_data(const uint8_t input[], size_t length) override;

      void final_result(uint8_t out[]) override;

      void ubi_512(const uint8_t msg[], size_t msg_len);

      void initial_block();

      void reset_tweak(type_code type, bool is_final);

      std::string m_personalization;

      size_t m_output_bits;

      std::unique_ptr<Threefish_512> m_threefish;

      secure_vector<uint64_t> m_T;

      secure_vector<uint8_t> m_buffer;

      size_t m_buf_pos;

   };

}

#endif