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crypt-vat.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-vat.cc,v 1.3 96/03/16 13:12:48 van Exp $ (LBL)";

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

extern "C" {
extern void DesQuickInit();
extern int DesMethod(u_char* m, const u_char* k);
extern int DesQuickFipsEncrypt(u_char* dst, const u_char* m, const u_char* src);
extern int DesQuickFipsDecrypt(u_char* dst, const u_char* m, const u_char* src);
}

class CryptVAT : public Crypt {
    public:
      CryptVAT();
      ~CryptVAT();
      virtual int command(int argc, const char*const* argv);
      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:
      int encrypt(u_int32_t* blk, const u_char* in, int len, u_char* rh);
      int decrypt(const u_char* in, int len, u_char* out, int rtcp);
      static int didinit_;
      u_char* wrkbuf_;
      u_char mkey_[128];
};

class CryptVATctrl : public CryptVAT {
    public:
      virtual u_char* Encrypt(const u_char* in, int& len);
      virtual int Decrypt(const u_char* in, int len, u_char* out);
};

static class CryptVATMatcher : public Matcher {
    public:
      CryptVATMatcher() : Matcher("crypt") {}
      TclObject* match(const char* id) {
            if (strcmp(id, "VAT/data") == 0)
                  return (new CryptVAT);
            if (strcmp(id, "VAT/ctrl") == 0)
                  return (new CryptVATctrl);
            return (0);
      }
} vat_matcher;

int CryptVAT::didinit_;

CryptVAT::CryptVAT()
{
      if (didinit_ == 0) {
            DesQuickInit();
            didinit_ = 1;
      }
      /* enough extra space for padding and RTCP 4-byte random header */
      wrkbuf_ = new u_char[RTP_MTU + 8 + 4];
}

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

int CryptVAT::install_key(const u_int8_t* keystr)
{
      /* DES key */
      u_char key[8];
      memset((char*)key, 0, sizeof(key));
      register int i, l = strlen((const char*)keystr);
      for (i = 0; i < l; ++i)
            key[i & 7] += keystr[i];

      /* make the key odd parity */
      for (i = 0; i < 8; ++i) {
            int j = key[i];
            j ^= j >> 4;
            j ^= j >> 2;
            j ^= j >> 1;
            if ((j & 1) == 0) {
                  j = 0x80;
                  while (key[i] & j)
                        j >>= 1;
                  key[i] |= j;
            }
      }
      return (DesMethod(mkey_, key));
}

int CryptVAT::command(int argc, const char*const* argv)
{
      if (argc == 3) {
            if (strcmp(argv[1], "key") == 0) {
                  Tcl& tcl = Tcl::instance();
                  if (install_key((const u_char*)argv[2]) != 0)
                        tcl.result("0");
                  else
                        tcl.result("1");
                  return (TCL_OK);
            }
      }
      return (Crypt::command(argc, argv));
}

int CryptVAT::encrypt(u_int32_t* blk, const u_char* in, int len, u_char* rh)
{
      int pad = len & 7;
      if (pad != 0) {
            /* pad to an block (8 octet) boundary */
            pad = 8 - pad;
            rh[1] |= 0x40; // set vat 'pad' bit
      }

      register u_int32_t* wp = (u_int32_t*)wrkbuf_;
      const u_char* m = mkey_;
      DesQuickFipsEncrypt((u_char*)wp, m, (const u_char*)blk);

      const u_int32_t* bp = (const u_int32_t*)in;
      for (int i = len >> 3; --i >= 0; ) {
            blk[0] = bp[0] ^ wp[0];
            blk[1] = bp[1] ^ wp[1];
            wp += 2;
            DesQuickFipsEncrypt((u_char*)wp, m, (const u_char*)blk);
            bp += 2;
      }
      if (pad > 0) {
            len += pad;
            blk[0] = bp[0];
            blk[1] = bp[1];
            u_char* cp = (u_char*)blk + 7;
            *cp = pad;
            while (--pad > 0)
                  *--cp = 0;
            blk[0] ^= wp[0];
            blk[1] ^= wp[1];
            wp += 2;
            DesQuickFipsEncrypt((u_char*)wp, m, (u_char*)blk);
      }
      return (len);
}

int CryptVAT::decrypt(const u_char* in, int len, u_char* out, int rtcp)
{
      register u_int32_t* wp = (u_int32_t*)out;
      const u_int32_t* bp = (const u_int32_t*)in;
      const u_char* m = mkey_;

      /* check that packet is an integral number of blocks */
      if ((len & 7) != 0) {
            ++badpktlen_;
            return (-1);
      }
      int nblk = len >> 3;
      DesQuickFipsDecrypt((u_char*)wp, m, (const u_char*)bp);
      bp += 2;
      nblk -= 1;
      if (rtcp) {
            /* throw away random RTCP header */
            wp[0] = wp[1];
            wp += 1;
            len -= 4;
      } else
            wp += 2;

      while (--nblk >= 0) {
            DesQuickFipsDecrypt((u_char*)wp, m, (const u_char*)bp);
            wp[0] ^= bp[-2];
            wp[1] ^= bp[-1];
            bp += 2;
            wp += 2;
      }
      if ((out[1] & 0x40) != 0) {
            /* P bit set - trim off padding */
            int pad = out[len - 1];
            if (pad > 7 || pad == 0) {
                  ++badpbit_;
                  return (-1);
            }
            len -= pad;
      }
      return (len);
}

u_char* CryptVAT::Encrypt(const u_char* in, int& len)
{
      u_int32_t blk[2];
      blk[0] = *(u_int32_t*)in;
      blk[1] = *(u_int32_t*)(in + 4);
      len = encrypt(blk, in + 8, len - 8, (u_char*)blk) + 8;
      return (wrkbuf_);
}

int CryptVAT::Decrypt(const u_char* in, int len, u_char* out)
{
      return (decrypt(in, len, out, 0));
}

u_char* CryptVATctrl::Encrypt(const u_char* in, int& len)
{
      if (len & 7) {
            u_char* cp = (u_char*)in + len;
            while (len & 7) {
                  *cp++ = 0;
                  ++len;
            }
      }
      return (CryptVAT::Encrypt(in, len));
}

int CryptVATctrl::Decrypt(const u_char* in, int len, u_char* out)
{
      return (CryptVAT::Decrypt(in, len, out));
}

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