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crypt-dull.cc

/*
 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the Network Research
 *    Group at Lawrence Berkeley National Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
static const char rcsid[] =
    "@(#) $Header: crypt-dull.cc,v 1.4 96/03/16 13:13:53 van Exp $ (LBL)";

#include "crypt.h"
#include "inet.h"
#include "rtp.h"

/*
 * A simple XOR data scrambler.  This is module is provided for test
 * purposes and to illustrate the extensibility of the encryption interface.
 *
 * This algorithm is trivial to crack using an obvious plaintext
 * attack.  It will only protect against accidental eavesdropping.
 */
class CryptDull : public Crypt {
    public:
      CryptDull();
      ~CryptDull();
      virtual int install_key(const u_int8_t* key);
      virtual u_char* Encrypt(const u_char* in, int& len);
      virtual int Decrypt(const u_char* in, int len, u_char* out);
    protected:
      void crypt(const u_int32_t* in, u_int32_t* out, int nw);
      u_int32_t key_;
      u_char* wrkbuf_;
};

static class CryptDullMatcher : public Matcher {
    public:
      CryptDullMatcher() : Matcher("crypt") {}
      TclObject* match(const char* id) {
            if (strcmp(id, "DULL/data") == 0 ||
                strcmp(id, "DULL/ctrl") == 0)
                  return (new CryptDull);
            else
                  return (0);
      }
} crypt_dull_matcher;

CryptDull::CryptDull()
{

      /* enough extra space for padding and RTCP 4-byte random header */
      wrkbuf_ = new u_char[RTP_MTU + 8 + 4];
}

CryptDull::~CryptDull()
{
      delete wrkbuf_;
}

int CryptDull::install_key(const u_int8_t* key)
{
      /* net order */
      key_ = *(u_int32_t*)key;
      return (0);
}

void CryptDull::crypt(const u_int32_t* in, u_int32_t* out, int nw)
{
      u_int32_t k = key_;
      for (int i = 0; i < nw; ++i)
            out[i] = in[i] ^ k;
}

u_char* CryptDull::Encrypt(const u_char* in, int& len)
{
      /*
       * assume input is word-aligned and we can read
       * past end to next longword boundary
       */
      crypt((const u_int32_t*)in, (u_int32_t*)wrkbuf_, (len + 3) >> 2);
      return (wrkbuf_);
}

int CryptDull::Decrypt(const u_char* in, int len, u_char* out)
{
      /*
       * assume input/output is word-aligned and we can read/write
       * past end to next longword boundary
       */
      crypt((const u_int32_t*)in, (u_int32_t*)out, (len + 3) >> 2);
      return (len);
}

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