encfs/cipher/NullCipher.cpp

/*****************************************************************************
 * Author:   Valient Gough <vgough@pobox.com>
 *
 *****************************************************************************
 * Copyright (c) 2004, Valient Gough
 *
 * This program 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.  
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "cipher/NullCipher.h"

#include "base/Range.h"
#include "base/Interface.h"
#include "base/shared_ptr.h"

#include <cstring>

using namespace std;

namespace encfs {

static Interface NullInterface = makeInterface( "nullCipher", 1, 0, 0 );
static Range NullKeyRange(0);
static Range NullBlockRange(1,4096,1);

static shared_ptr<Cipher> NewNullCipher(const Interface &iface, int keyLen)
{
  (void)keyLen;
  return shared_ptr<Cipher>( new NullCipher( iface ) );
}

const bool HiddenCipher = true;

static bool NullCipher_registered = Cipher::Register("Null",
    "Non encrypting cipher.  For testing only!",
    NullInterface, NullKeyRange, NullBlockRange, NewNullCipher,
    HiddenCipher);

class NullKey : public AbstractCipherKey
{
public:
  NullKey() {}
  virtual ~NullKey() {}
};

class NullDestructor
{
public:
  NullDestructor() {}
  NullDestructor(const NullDestructor &) {}
  ~NullDestructor() {}

  NullDestructor &operator = (const NullDestructor &){ return *this; }
  void operator ()(NullKey *&) {}
};

shared_ptr<AbstractCipherKey> gNullKey( new NullKey(), NullDestructor() );

NullCipher::NullCipher(const Interface &iface_)
{
  this->iface = iface_;
}

NullCipher::~NullCipher()
{
}

Interface NullCipher::interface() const
{
  return iface;
}

CipherKey NullCipher::newKey(const char *, int,
        int &, long, const byte *, int )
{
  return gNullKey;
}

CipherKey NullCipher::newKey(const char *, int)
{
  return gNullKey;
}

CipherKey NullCipher::newRandomKey()
{
  return gNullKey;
}

bool NullCipher::randomize( byte *buf, int len, bool ) const
{
  memset( buf, 0, len );
  return true;
}

uint64_t NullCipher::MAC_64(const byte *, int , 
    const CipherKey &, uint64_t *) const
{
  return 0;
}

CipherKey NullCipher::readKey( const byte *, 
    const CipherKey &, bool)
{
  return gNullKey;
}

void NullCipher::writeKey(const CipherKey &, byte *, 
    const CipherKey &)
{
}

bool NullCipher::compareKey(const CipherKey &A_, 
    const CipherKey &B_) const
{
  shared_ptr<NullKey> A = dynamic_pointer_cast<NullKey>(A_);
  shared_ptr<NullKey> B = dynamic_pointer_cast<NullKey>(B_);
  return A.get() == B.get();
}

int NullCipher::encodedKeySize() const
{
  return 0;
}

int NullCipher::keySize() const
{
  return 0;
}

int NullCipher::cipherBlockSize() const
{
  return 1;
}

bool NullCipher::streamEncode( byte *src, int len,
    uint64_t iv64, const CipherKey &key) const
{
  (void)src;
  (void)len;
  (void)iv64;
  (void)key;
  return true;
}

bool NullCipher::streamDecode( byte *src, int len,
    uint64_t iv64, const CipherKey &key) const
{
  (void)src;
  (void)len;
  (void)iv64;
  (void)key;
  return true;
}

bool NullCipher::blockEncode( byte *, int , uint64_t, 
    const CipherKey & ) const
{
  return true;
}

bool NullCipher::blockDecode( byte *, int, uint64_t, 
    const CipherKey & ) const
{
  return true;
}

bool NullCipher::Enabled()
{
  return true;
}

}  // namespace encfs