ctr.h

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/*
* CTR-BE Mode
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#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)
*/
class BOTAN_DLL CTR_BE : public StreamCipher
   {
   public:
      void cipher(const byte in[], byte out[], size_t length);
 
      void set_iv(const byte iv[], size_t iv_len);
 
      bool valid_iv_length(size_t iv_len) const
         { return (iv_len <= permutation->block_size()); }
 
      Key_Length_Specification key_spec() const
         {
         return permutation->key_spec();
         }
 
      std::string name() const;
 
      CTR_BE* clone() const
         { return new CTR_BE(permutation->clone()); }
 
      void clear();
 
      /**
      * @param cipher the underlying block cipher to use
      */
      CTR_BE(BlockCipher* cipher);
      ~CTR_BE();
   private:
      void key_schedule(const byte key[], size_t key_len);
      void increment_counter();
 
      BlockCipher* permutation;
      SecureVector<byte> counter, buffer;
      size_t position;
   };
 
}
 
#endif