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enc_des.c

/*-
 * Copyright (c) 1991, 1993
 *    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 University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    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.
 */

#include <config.h>

RCSID("$Id: enc_des.c,v 1.21 2002/09/10 20:03:47 joda Exp $");

#if   defined(AUTHENTICATION) && defined(ENCRYPTION) && defined(DES_ENCRYPTION)
#include <arpa/telnet.h>
#include <stdio.h>
#ifdef      __STDC__
#include <stdlib.h>
#include <string.h>
#endif
#include <roken.h>
#ifdef SOCKS
#include <socks.h>
#endif

#include "encrypt.h"
#include "misc-proto.h"

#include "crypto-headers.h"

extern int encrypt_debug_mode;

#define     CFB   0
#define     OFB   1

#define     NO_SEND_IV  1
#define     NO_RECV_IV  2
#define     NO_KEYID    4
#define     IN_PROGRESS (NO_SEND_IV|NO_RECV_IV|NO_KEYID)
#define     SUCCESS           0
#define     FAILED            -1


struct stinfo {
  des_cblock      str_output;
  des_cblock      str_feed;
  des_cblock      str_iv;
  des_cblock      str_ikey;
  des_key_schedule str_sched;
  int       str_index;
  int       str_flagshift;
};

struct fb {
      des_cblock krbdes_key;
      des_key_schedule krbdes_sched;
      des_cblock temp_feed;
      unsigned char fb_feed[64];
      int need_start;
      int state[2];
      int keyid[2];
      int once;
      struct stinfo streams[2];
};

static struct fb fb[2];

struct keyidlist {
      char  *keyid;
      int   keyidlen;
      char  *key;
      int   keylen;
      int   flags;
} keyidlist [] = {
      { "\0", 1, 0, 0, 0 },         /* default key of zero */
      { 0, 0, 0, 0, 0 }
};

#define     KEYFLAG_MASK      03

#define     KEYFLAG_NOINIT    00
#define     KEYFLAG_INIT      01
#define     KEYFLAG_OK  02
#define     KEYFLAG_BAD 03

#define     KEYFLAG_SHIFT     2

#define     SHIFT_VAL(a,b)    (KEYFLAG_SHIFT*((a)+((b)*2)))

#define     FB64_IV           1
#define     FB64_IV_OK  2
#define     FB64_IV_BAD 3


void fb64_stream_iv (des_cblock, struct stinfo *);
void fb64_init (struct fb *);
static int fb64_start (struct fb *, int, int);
int fb64_is (unsigned char *, int, struct fb *);
int fb64_reply (unsigned char *, int, struct fb *);
static void fb64_session (Session_Key *, int, struct fb *);
void fb64_stream_key (des_cblock, struct stinfo *);
int fb64_keyid (int, unsigned char *, int *, struct fb *);
void fb64_printsub(unsigned char *, int ,
               unsigned char *, int , char *);

void cfb64_init(int server)
{
      fb64_init(&fb[CFB]);
      fb[CFB].fb_feed[4] = ENCTYPE_DES_CFB64;
      fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, CFB);
      fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, CFB);
}


void ofb64_init(int server)
{
      fb64_init(&fb[OFB]);
      fb[OFB].fb_feed[4] = ENCTYPE_DES_OFB64;
      fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, OFB);
      fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, OFB);
}

void fb64_init(struct fb *fbp)
{
      memset(fbp,0, sizeof(*fbp));
      fbp->state[0] = fbp->state[1] = FAILED;
      fbp->fb_feed[0] = IAC;
      fbp->fb_feed[1] = SB;
      fbp->fb_feed[2] = TELOPT_ENCRYPT;
      fbp->fb_feed[3] = ENCRYPT_IS;
}

/*
 * Returns:
 *    -1: some error.  Negotiation is done, encryption not ready.
 *     0: Successful, initial negotiation all done.
 *     1: successful, negotiation not done yet.
 *     2: Not yet.  Other things (like getting the key from
 *        Kerberos) have to happen before we can continue.
 */
int cfb64_start(int dir, int server)
{
      return(fb64_start(&fb[CFB], dir, server));
}

int ofb64_start(int dir, int server)
{
      return(fb64_start(&fb[OFB], dir, server));
}

static int fb64_start(struct fb *fbp, int dir, int server)
{
      int x;
      unsigned char *p;
      int state;

      switch (dir) {
      case DIR_DECRYPT:
            /*
             * This is simply a request to have the other side
             * start output (our input).  He will negotiate an
             * IV so we need not look for it.
             */
            state = fbp->state[dir-1];
            if (state == FAILED)
                  state = IN_PROGRESS;
            break;

      case DIR_ENCRYPT:
            state = fbp->state[dir-1];
            if (state == FAILED)
                  state = IN_PROGRESS;
            else if ((state & NO_SEND_IV) == 0) {
                  break;
            }

            if (!VALIDKEY(fbp->krbdes_key)) {
                    fbp->need_start = 1;
                  break;
            }

            state &= ~NO_SEND_IV;
            state |= NO_RECV_IV;
            if (encrypt_debug_mode)
                  printf("Creating new feed\r\n");
            /*
             * Create a random feed and send it over.
             */
#ifndef OLD_DES_RANDOM_KEY
            des_new_random_key(&fbp->temp_feed);
#else
            /*
             * From des_cryp.man "If the des_check_key flag is non-zero,
             *  des_set_key will check that the key passed is
             *  of odd parity and is not a week or semi-weak key."
             */
            do {
                  des_random_key(fbp->temp_feed);
                  des_set_odd_parity(fbp->temp_feed);
            } while (des_is_weak_key(fbp->temp_feed));
#endif
            des_ecb_encrypt(&fbp->temp_feed,
                        &fbp->temp_feed,
                        fbp->krbdes_sched, 1);
            p = fbp->fb_feed + 3;
            *p++ = ENCRYPT_IS;
            p++;
            *p++ = FB64_IV;
            for (x = 0; x < sizeof(des_cblock); ++x) {
                  if ((*p++ = fbp->temp_feed[x]) == IAC)
                        *p++ = IAC;
            }
            *p++ = IAC;
            *p++ = SE;
            printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
            telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);
            break;
      default:
            return(FAILED);
      }
      return(fbp->state[dir-1] = state);
}

/*
 * Returns:
 *    -1: some error.  Negotiation is done, encryption not ready.
 *     0: Successful, initial negotiation all done.
 *     1: successful, negotiation not done yet.
 */

int cfb64_is(unsigned char *data, int cnt)
{
      return(fb64_is(data, cnt, &fb[CFB]));
}

int ofb64_is(unsigned char *data, int cnt)
{
      return(fb64_is(data, cnt, &fb[OFB]));
}


int fb64_is(unsigned char *data, int cnt, struct fb *fbp)
{
      unsigned char *p;
      int state = fbp->state[DIR_DECRYPT-1];

      if (cnt-- < 1)
            goto failure;

      switch (*data++) {
      case FB64_IV:
            if (cnt != sizeof(des_cblock)) {
                  if (encrypt_debug_mode)
                        printf("CFB64: initial vector failed on size\r\n");
                  state = FAILED;
                  goto failure;
            }

            if (encrypt_debug_mode)
                  printf("CFB64: initial vector received\r\n");

            if (encrypt_debug_mode)
                  printf("Initializing Decrypt stream\r\n");

            fb64_stream_iv(data, &fbp->streams[DIR_DECRYPT-1]);

            p = fbp->fb_feed + 3;
            *p++ = ENCRYPT_REPLY;
            p++;
            *p++ = FB64_IV_OK;
            *p++ = IAC;
            *p++ = SE;
            printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
            telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);

            state = fbp->state[DIR_DECRYPT-1] = IN_PROGRESS;
            break;

      default:
            if (encrypt_debug_mode) {
                  printf("Unknown option type: %d\r\n", *(data-1));
                  printd(data, cnt);
                  printf("\r\n");
            }
            /* FALL THROUGH */
      failure:
            /*
             * We failed.  Send an FB64_IV_BAD option
             * to the other side so it will know that
             * things failed.
             */
            p = fbp->fb_feed + 3;
            *p++ = ENCRYPT_REPLY;
            p++;
            *p++ = FB64_IV_BAD;
            *p++ = IAC;
            *p++ = SE;
            printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
            telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);

            break;
      }
      return(fbp->state[DIR_DECRYPT-1] = state);
}

/*
 * Returns:
 *    -1: some error.  Negotiation is done, encryption not ready.
 *     0: Successful, initial negotiation all done.
 *     1: successful, negotiation not done yet.
 */

int cfb64_reply(unsigned char *data, int cnt)
{
      return(fb64_reply(data, cnt, &fb[CFB]));
}

int ofb64_reply(unsigned char *data, int cnt)
{
      return(fb64_reply(data, cnt, &fb[OFB]));
}


int fb64_reply(unsigned char *data, int cnt, struct fb *fbp)
{
      int state = fbp->state[DIR_ENCRYPT-1];

      if (cnt-- < 1)
            goto failure;

      switch (*data++) {
      case FB64_IV_OK:
            fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
            if (state == FAILED)
                  state = IN_PROGRESS;
            state &= ~NO_RECV_IV;
            encrypt_send_keyid(DIR_ENCRYPT, (unsigned char *)"\0", 1, 1);
            break;

      case FB64_IV_BAD:
            memset(fbp->temp_feed, 0, sizeof(des_cblock));
            fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
            state = FAILED;
            break;

      default:
            if (encrypt_debug_mode) {
                  printf("Unknown option type: %d\r\n", data[-1]);
                  printd(data, cnt);
                  printf("\r\n");
            }
            /* FALL THROUGH */
      failure:
            state = FAILED;
            break;
      }
      return(fbp->state[DIR_ENCRYPT-1] = state);
}

void cfb64_session(Session_Key *key, int server)
{
      fb64_session(key, server, &fb[CFB]);
}

void ofb64_session(Session_Key *key, int server)
{
      fb64_session(key, server, &fb[OFB]);
}

static void fb64_session(Session_Key *key, int server, struct fb *fbp)
{

      if (!key || key->type != SK_DES) {
            if (encrypt_debug_mode)
                  printf("Can't set krbdes's session key (%d != %d)\r\n",
                        key ? key->type : -1, SK_DES);
            return;
      }
      memcpy(fbp->krbdes_key, key->data, sizeof(des_cblock));

      fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_ENCRYPT-1]);
      fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_DECRYPT-1]);

      if (fbp->once == 0) {
#if !defined(OLD_DES_RANDOM_KEY) && !defined(HAVE_OPENSSL)
            des_init_random_number_generator(&fbp->krbdes_key);
#endif
            fbp->once = 1;
      }
      des_key_sched(&fbp->krbdes_key, fbp->krbdes_sched);
      /*
       * Now look to see if krbdes_start() was was waiting for
       * the key to show up.  If so, go ahead an call it now
       * that we have the key.
       */
      if (fbp->need_start) {
            fbp->need_start = 0;
            fb64_start(fbp, DIR_ENCRYPT, server);
      }
}

/*
 * We only accept a keyid of 0.  If we get a keyid of
 * 0, then mark the state as SUCCESS.
 */

int cfb64_keyid(int dir, unsigned char *kp, int *lenp)
{
      return(fb64_keyid(dir, kp, lenp, &fb[CFB]));
}

int ofb64_keyid(int dir, unsigned char *kp, int *lenp)
{
      return(fb64_keyid(dir, kp, lenp, &fb[OFB]));
}

int fb64_keyid(int dir, unsigned char *kp, int *lenp, struct fb *fbp)
{
      int state = fbp->state[dir-1];

      if (*lenp != 1 || (*kp != '\0')) {
            *lenp = 0;
            return(state);
      }

      if (state == FAILED)
            state = IN_PROGRESS;

      state &= ~NO_KEYID;

      return(fbp->state[dir-1] = state);
}

void fb64_printsub(unsigned char *data, int cnt, 
               unsigned char *buf, int buflen, char *type)
{
      char lbuf[32];
      int i;
      char *cp;

      buf[buflen-1] = '\0';         /* make sure it's NULL terminated */
      buflen -= 1;

      switch(data[2]) {
      case FB64_IV:
            snprintf(lbuf, sizeof(lbuf), "%s_IV", type);
            cp = lbuf;
            goto common;

      case FB64_IV_OK:
            snprintf(lbuf, sizeof(lbuf), "%s_IV_OK", type);
            cp = lbuf;
            goto common;

      case FB64_IV_BAD:
            snprintf(lbuf, sizeof(lbuf), "%s_IV_BAD", type);
            cp = lbuf;
            goto common;

      default:
            snprintf(lbuf, sizeof(lbuf), " %d (unknown)", data[2]);
            cp = lbuf;
      common:
            for (; (buflen > 0) && (*buf = *cp++); buf++)
                  buflen--;
            for (i = 3; i < cnt; i++) {
                  snprintf(lbuf, sizeof(lbuf), " %d", data[i]);
                  for (cp = lbuf; (buflen > 0) && (*buf = *cp++); buf++)
                        buflen--;
            }
            break;
      }
}

void cfb64_printsub(unsigned char *data, int cnt, 
                unsigned char *buf, int buflen)
{
      fb64_printsub(data, cnt, buf, buflen, "CFB64");
}

void ofb64_printsub(unsigned char *data, int cnt,
                unsigned char *buf, int buflen)
{
      fb64_printsub(data, cnt, buf, buflen, "OFB64");
}

void fb64_stream_iv(des_cblock seed, struct stinfo *stp)
{

      memcpy(stp->str_iv, seed,sizeof(des_cblock));
      memcpy(stp->str_output, seed, sizeof(des_cblock));

      des_key_sched(&stp->str_ikey, stp->str_sched);

      stp->str_index = sizeof(des_cblock);
}

void fb64_stream_key(des_cblock key, struct stinfo *stp)
{
      memcpy(stp->str_ikey, key, sizeof(des_cblock));
      des_key_sched((des_cblock*)key, stp->str_sched);

      memcpy(stp->str_output, stp->str_iv, sizeof(des_cblock));

      stp->str_index = sizeof(des_cblock);
}

/*
 * DES 64 bit Cipher Feedback
 *
 *     key --->+-----+
 *          +->| DES |--+
 *          |  +-----+  |
 *        |           v
 *  INPUT --(--------->(+)+---> DATA
 *          |             |
 *        +-------------+
 *         
 *
 * Given:
 *    iV: Initial vector, 64 bits (8 bytes) long.
 *    Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
 *    On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
 *
 *    V0 = DES(iV, key)
 *    On = Dn ^ Vn
 *    V(n+1) = DES(On, key)
 */

void cfb64_encrypt(unsigned char *s, int c)
{
      struct stinfo *stp = &fb[CFB].streams[DIR_ENCRYPT-1];
      int index;

      index = stp->str_index;
      while (c-- > 0) {
            if (index == sizeof(des_cblock)) {
                  des_cblock b;
                  des_ecb_encrypt(&stp->str_output, &b,stp->str_sched, 1);
                  memcpy(stp->str_feed, b, sizeof(des_cblock));
                  index = 0;
            }

            /* On encryption, we store (feed ^ data) which is cypher */
            *s = stp->str_output[index] = (stp->str_feed[index] ^ *s);
            s++;
            index++;
      }
      stp->str_index = index;
}

int cfb64_decrypt(int data)
{
      struct stinfo *stp = &fb[CFB].streams[DIR_DECRYPT-1];
      int index;

      if (data == -1) {
            /*
             * Back up one byte.  It is assumed that we will
             * never back up more than one byte.  If we do, this
             * may or may not work.
             */
            if (stp->str_index)
                  --stp->str_index;
            return(0);
      }

      index = stp->str_index++;
      if (index == sizeof(des_cblock)) {
            des_cblock b;
            des_ecb_encrypt(&stp->str_output,&b, stp->str_sched, 1);
            memcpy(stp->str_feed, b, sizeof(des_cblock));
            stp->str_index = 1;     /* Next time will be 1 */
            index = 0;        /* But now use 0 */ 
      }

      /* On decryption we store (data) which is cypher. */
      stp->str_output[index] = data;
      return(data ^ stp->str_feed[index]);
}

/*
 * DES 64 bit Output Feedback
 *
 * key --->+-----+
 *    +->| DES |--+
 *    |  +-----+  |
 *    +-----------+
 *                v
 *  INPUT -------->(+) ----> DATA
 *
 * Given:
 *    iV: Initial vector, 64 bits (8 bytes) long.
 *    Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
 *    On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
 *
 *    V0 = DES(iV, key)
 *    V(n+1) = DES(Vn, key)
 *    On = Dn ^ Vn
 */

void ofb64_encrypt(unsigned char *s, int c)
{
      struct stinfo *stp = &fb[OFB].streams[DIR_ENCRYPT-1];
      int index;

      index = stp->str_index;
      while (c-- > 0) {
            if (index == sizeof(des_cblock)) {
                  des_cblock b;
                  des_ecb_encrypt(&stp->str_feed,&b, stp->str_sched, 1);
                  memcpy(stp->str_feed, b, sizeof(des_cblock));
                  index = 0;
            }
            *s++ ^= stp->str_feed[index];
            index++;
      }
      stp->str_index = index;
}

int ofb64_decrypt(int data)
{
      struct stinfo *stp = &fb[OFB].streams[DIR_DECRYPT-1];
      int index;

      if (data == -1) {
            /*
             * Back up one byte.  It is assumed that we will
             * never back up more than one byte.  If we do, this
             * may or may not work.
             */
            if (stp->str_index)
                  --stp->str_index;
            return(0);
      }

      index = stp->str_index++;
      if (index == sizeof(des_cblock)) {
            des_cblock b;
            des_ecb_encrypt(&stp->str_feed,&b,stp->str_sched, 1);
            memcpy(stp->str_feed, b, sizeof(des_cblock));
            stp->str_index = 1;     /* Next time will be 1 */
            index = 0;        /* But now use 0 */ 
      }

      return(data ^ stp->str_feed[index]);
}
#endif


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