ctr.hpp

/*
  ANCH Framework: ANother C++ Hack is a C++ framework based on C++11 standard
  Copyright (C) 2012 Vincent Lachenal
 
  This file is part of ANCH Framework.
 
  ANCH Framework is free software: you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
 
  ANCH Framework is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public License
  along with ANCH Framework.  If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
 
#include "crypto/cipher/bcModOp.hpp"
 
namespace anch {
  namespace crypto {

    template<typename Cipher>
    class CTR: public BlockCipherModeOfOperation<CTR<Cipher>,Cipher> {
 
      // Attributes +
    private:
      std::array<uint8_t,Cipher::getBlockSize()> _nonce;
      // Attributes -
 
 
      // Constructors +
    public:
      CTR(const std::array<uint8_t,Cipher::getBlockSize()>& nonce, unsigned int nbThread = 1);
      // Constructors -
 
 
      // Destructor +
      virtual ~CTR();
      // Destructor -
 
 
      // Methods +
    protected:
      virtual std::size_t cipherBlock(std::array<uint8_t,Cipher::getBlockSize()>& input,
                                      std::streamsize nbRead,
                                      std::array<uint8_t,Cipher::getBlockSize()>& output,
                                      uint32_t index,
                                      Cipher& cipher) override;

      virtual std::size_t decipherBlock(std::array<uint8_t,Cipher::getBlockSize()>& input,
                                        std::array<uint8_t,Cipher::getBlockSize()>&,
                                        std::streamsize nbRead,
                                        bool,
                                        std::array<uint8_t,Cipher::getBlockSize()>& output,
                                        uint32_t index,
                                        Cipher& cipher) override;

      virtual const std::array<uint8_t,Cipher::getBlockSize()>& reset();
      // Methods -
 
    };
 
    // Constructors +
    template<typename Cipher>
    CTR<Cipher>::CTR(const std::array<uint8_t,Cipher::getBlockSize()>& nonce, unsigned int nbThread):
      BlockCipherModeOfOperation<CTR<Cipher>,Cipher>(true, true, nbThread),
      _nonce(nonce) {
      // Nothing to do
    }
    // Constructors -
 
 
    // Destructor +
    template<typename Cipher>
    CTR<Cipher>::~CTR() {
      // Nothing to do
    }
    // Destructor -
 
 
    // Methods +
    template<typename Cipher>
    std::size_t
    CTR<Cipher>::cipherBlock(std::array<uint8_t,Cipher::getBlockSize()>& input,
                             std::streamsize nbRead,
                             std::array<uint8_t,Cipher::getBlockSize()>& output,
                             uint32_t index,
                             Cipher& cipher) {
      std::array<uint8_t,Cipher::getBlockSize()> ctxtVect(_nonce);
      uint16_t* counter = reinterpret_cast<uint16_t*>(&ctxtVect.data()[Cipher::getBlockSize() - 2]);
      *counter = static_cast<uint16_t>(index);
      std::array<uint8_t,Cipher::getBlockSize()> data;
      cipher.cipher(ctxtVect, data);
      for(std::size_t i = 0 ; i < static_cast<std::size_t>(nbRead) ; ++i) {
        output[i] = input[i] ^ data[i];
      }
      return static_cast<std::size_t>(nbRead);
    }
 
    template<typename Cipher>
    std::size_t
    CTR<Cipher>::decipherBlock(std::array<uint8_t,Cipher::getBlockSize()>& input,
                               std::array<uint8_t,Cipher::getBlockSize()>&,
                               std::streamsize nbRead,
                               bool,
                               std::array<uint8_t,Cipher::getBlockSize()>& output,
                               uint32_t index,
                               Cipher& cipher) {
      std::array<uint8_t,Cipher::getBlockSize()> ctxtVect(_nonce);
      uint16_t* counter = reinterpret_cast<uint16_t*>(&ctxtVect.data()[Cipher::getBlockSize() - 2]);
      *counter = static_cast<uint16_t>(index);
      std::array<uint8_t,Cipher::getBlockSize()> data;
      cipher.cipher(ctxtVect, data);
      for(std::size_t i = 0 ; i < static_cast<std::size_t>(nbRead) ; ++i) {
        output[i] = input[i] ^ data[i];
      }
      return static_cast<std::size_t>(nbRead);
    }
 
    template<typename Cipher>
    const std::array<uint8_t,Cipher::getBlockSize()>&
    CTR<Cipher>::reset() {
      return _nonce;
    }
    // Methods -
 
  }
}