/*

* Lion

* (C) 1999-2007,2014 Jack Lloyd

*

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

*/

#ifndef BOTAN_LION_H_

#define BOTAN_LION_H_

#include <botan/block_cipher.h>

#include <botan/stream_cipher.h>

#include <botan/hash.h>

namespace Botan {

/**

* Lion is a block cipher construction designed by Ross Anderson and

* Eli Biham, described in "Two Practical and Provably Secure Block

* Ciphers: BEAR and LION". It has a variable block size and is

* designed to encrypt very large blocks (up to a megabyte)

* https://www.cl.cam.ac.uk/~rja14/Papers/bear-lion.pdf

*/

class Lion final : public BlockCipher

   {

   public:

      void encrypt_n(const uint8_t in[], uint8_t out[], size_t blocks) const override;

      void decrypt_n(const uint8_t in[], uint8_t out[], size_t blocks) const override;

      size_t block_size() const override { return m_block_size; }

      Key_Length_Specification key_spec() const override

         {

         return Key_Length_Specification(2, 2*m_hash->output_length(), 2);

         }

      void clear() override;

      std::string name() const override;

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

      /**

      * @param hash the hash to use internally

      * @param cipher the stream cipher to use internally

      * @param block_size the size of the block to use

      */

      Lion(std::unique_ptr<HashFunction> hash,

           std::unique_ptr<StreamCipher> cipher,

           size_t block_size);

   private:

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

      size_t left_size() const { return m_hash->output_length(); }

      size_t right_size() const { return m_block_size - left_size(); }

      const size_t m_block_size;

      std::unique_ptr<HashFunction> m_hash;

      std::unique_ptr<StreamCipher> m_cipher;

      secure_vector<uint8_t> m_key1, m_key2;

   };

}

#endif