randombit / botan / 4834822395

/*

* CTR-BE Mode

* (C) 1999-2007 Jack Lloyd

*

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

*/

#ifndef BOTAN_CTR_BE_H_

#define BOTAN_CTR_BE_H_

#include <botan/block_cipher.h>

#include <botan/stream_cipher.h>

namespace Botan {

/**

* CTR-BE (Counter mode, big-endian)

*/

   {

   public:

      size_t default_iv_length() const override;

      bool valid_iv_length(size_t iv_len) const override;

      Key_Length_Specification key_spec() const override;

      std::string name() const override;

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

      void clear() override;

      bool has_keying_material() const override;

      size_t buffer_size() const override;

      /**

      * @param cipher the block cipher to use

      */

      explicit CTR_BE(std::unique_ptr<BlockCipher> cipher);

      CTR_BE(std::unique_ptr<BlockCipher> cipher, size_t ctr_size);

      void seek(uint64_t offset) override;

   private:

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

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

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

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

      void add_counter(const uint64_t counter);

      std::unique_ptr<BlockCipher> m_cipher;

      const size_t m_block_size;

      const size_t m_ctr_size;

      const size_t m_ctr_blocks;

      secure_vector<uint8_t> m_counter, m_pad;

      std::vector<uint8_t> m_iv;

      size_t m_pad_pos;

   };

}

#endif