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/* modes.hpp
*
* Copyright (C) 2003 Sawtooth Consulting Ltd.
*
* This file is part of yaSSL.
*
* yaSSL is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* yaSSL 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
/* modes.hpp provides ECB and CBC modes for block cipher encryption/decryption
*/
#ifndef TAO_CRYPT_MODES_HPP
#define TAO_CRYPT_MODES_HPP
#include "misc.hpp"
namespace TaoCrypt {
enum Mode { ECB, CBC };
// BlockCipher abstraction
template<CipherDir DIR, class T, Mode MODE>
class BlockCipher {
public:
BlockCipher() : cipher_(DIR, MODE) {}
void Process(byte* c, const byte* p, word32 sz)
{ cipher_.Process(c, p, sz); }
void SetKey(const byte* k, word32 sz)
{ cipher_.SetKey(k, sz, DIR); }
void SetKey(const byte* k, word32 sz, const byte* iv)
{ cipher_.SetKey(k, sz, DIR); cipher_.SetIV(iv); }
private:
T cipher_;
BlockCipher(const BlockCipher&); // hide copy
BlockCipher& operator=(const BlockCipher&); // and assign
};
// Mode Base for block ciphers, static size
class Mode_BASE : public virtual_base {
public:
enum { MaxBlockSz = 16 };
explicit Mode_BASE(int sz)
: blockSz_(sz), reg_(reinterpret_cast<byte*>(r_)),
tmp_(reinterpret_cast<byte*>(t_))
{
assert(sz <= MaxBlockSz);
}
virtual ~Mode_BASE() {}
void SetIV(const byte* iv) { memcpy(reg_, iv, blockSz_); }
protected:
int blockSz_;
byte* reg_;
byte* tmp_;
word32 r_[MaxBlockSz / sizeof(word32)]; // align reg_ on word32
word32 t_[MaxBlockSz / sizeof(word32)]; // align tmp_ on word32
void ECB_Process(byte*, const byte*, word32);
void CBC_Encrypt(byte*, const byte*, word32);
void CBC_Decrypt(byte*, const byte*, word32);
Mode_BASE(const Mode_BASE&); // hide copy
Mode_BASE& operator=(const Mode_BASE&); // and assign
private:
virtual void ProcessAndXorBlock(const byte*, const byte*, byte*) const = 0;
};
// ECB Process blocks
inline void Mode_BASE::ECB_Process(byte* out, const byte* in, word32 sz)
{
word32 blocks = sz / blockSz_;
while (blocks--) {
ProcessAndXorBlock(in, 0, out);
out += blockSz_;
in += blockSz_;
}
}
// CBC Encrypt
inline void Mode_BASE::CBC_Encrypt(byte* out, const byte* in, word32 sz)
{
word32 blocks = sz / blockSz_;
while (blocks--) {
xorbuf(reg_, in, blockSz_);
ProcessAndXorBlock(reg_, 0, reg_);
memcpy(out, reg_, blockSz_);
out += blockSz_;
in += blockSz_;
}
}
// CBC Decrypt
inline void Mode_BASE::CBC_Decrypt(byte* out, const byte* in, word32 sz)
{
word32 blocks = sz / blockSz_;
byte hold[MaxBlockSz];
while (blocks--) {
memcpy(tmp_, in, blockSz_);
ProcessAndXorBlock(tmp_, 0, out);
xorbuf(out, reg_, blockSz_);
memcpy(hold, reg_, blockSz_); // swap reg_ and tmp_
memcpy(reg_, tmp_, blockSz_);
memcpy(tmp_, hold, blockSz_);
out += blockSz_;
in += blockSz_;
}
}
} // namespace
#endif // TAO_CRYPT_MODES_HPP
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