lib/libcrypt/krb_des.c

/*-
 * Copyright (c) 1991 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.
 */

#ifndef lint
static char sccsid[] = "@(#)krb_des.c   5.1 (Berkeley) 2/28/91";
#endif /* not lint */

/*
 * Copyright (C) 1990 by the Massachusetts Institute of Technology
 *
 * Export of this software from the United States of America is assumed
 * to require a specific license from the United States Government.
 * It is the responsibility of any person or organization contemplating
 * export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 */

#if     defined(AUTHENTICATE) && defined(ENCRYPT) && defined(KRBDES_ENCRYPT)
#include <arpa/telnet.h>
#include <stdio.h>
#ifdef  __STDC__
#include <stdlib.h>
#endif

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

extern encrypt_debug_mode;

static Block krbdes_key = { 0 };
static Schedule krbdes_sched = { 0 };
static Block input_feed = { 0 };
static Block output_feed = { 0 };
static Block temp_feed = { 0 };

static unsigned char str_feed[64] = { IAC, SB, TELOPT_ENCRYPT,
                                      ENCRYPT_IS,
                                      ENCTYPE_KRBDES, };

        void
krbdes_init(server)
        int server;
{
        bzero((void *)krbdes_key, sizeof(Block));
        bzero((void *)krbdes_sched, sizeof(Schedule));
        bzero((void *)input_feed, sizeof(Block));
        bzero((void *)output_feed, sizeof(Block));
}

#define KRBDES_FEED_INIT        1
#define KRBDES_FEED_VRFY        2
#define KRBDES_FEED_FAIL        3
#define KRBDES_FEED_OK          4
#define KRBDES_FEED_VRFY_FAIL   5

/*
 * 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.
 */


#define NOT_YET         2
#define IN_PROGRESS     1
#define SUCCESS         0
#define FAILED          -1

int state[2] = { NOT_YET, NOT_YET };
#define ENCRYPT_STATE 0
#define DECRYPT_STATE 1

/*
 * This is where we keep track of the fact that there has been a
 * call to krbdes_start(), but we haven't gotten a valid key from
 * kerberos, so that when (if) it does come in, we can continue with
 * the initial encryption startup.
 */
static int need_start;

        int
krbdes_start(dir, server)
        int dir;
        int server;
{
        Block b;
        int x;
        unsigned char *p;

        switch (dir) {
        case DIR_DECRYPT:
                /*
                 * This is simply a request to have the other side
                 * start output (our input).  He will negotiate a
                 * feed so we need not look for it.
                 */
                if (!VALIDKEY(krbdes_key))
                        return(state[DECRYPT_STATE]);
                if (state[DECRYPT_STATE] == NOT_YET)
                        state[DECRYPT_STATE] = IN_PROGRESS;
                return(state[DECRYPT_STATE]);

        case DIR_ENCRYPT:
                if (!VALIDKEY(krbdes_key)) {
                        need_start = 1;
                        return(state[ENCRYPT_STATE]);
                }
                if (state[ENCRYPT_STATE] == IN_PROGRESS)
                        return(IN_PROGRESS);
                if (VALIDKEY(output_feed))
                        return(SUCCESS);
                if (encrypt_debug_mode)
                        printf("Creating new feed\r\n");
                /*
                 * Create a random feed and send it over encrypted.
                 * The other side will decrypt it, xor in 'KRBDES'
                 * and then recrypt it and send it back.
                 */
                des_new_random_key(temp_feed);
                des_ecb_encrypt(temp_feed, b, krbdes_sched, 1);
                str_feed[3] = ENCRYPT_IS;
                p = str_feed + 5;
                *p++ = KRBDES_FEED_INIT;
                for (x = 0; x < sizeof(Block); ++x) {
                        if ((*p++ = b[x]) == IAC)
                                *p++ = IAC;
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &str_feed[2], p - &str_feed[2]);
                net_write(str_feed, p - str_feed);
                temp_feed[0] ^= 'K';
                temp_feed[1] ^= 'R';
                temp_feed[2] ^= 'B';
                temp_feed[3] ^= 'D';
                temp_feed[4] ^= 'E';
                temp_feed[5] ^= 'S';
                state[ENCRYPT_STATE] = IN_PROGRESS;
                return(IN_PROGRESS);
        default:
                return(FAILED);
        }
}

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

        int
krbdes_is(data, cnt)
        unsigned char *data;
        int cnt;
{
        int x;
        unsigned char *p;
        unsigned char *why = 0;
        Block b;

        if (cnt-- < 1) {
                why = (unsigned char *)"Bad IS suboption";
                goto failure;
        }

        switch (*data++) {
        case KRBDES_FEED_INIT:
                if (cnt != sizeof(Block)) {
                        if (encrypt_debug_mode)
                                printf("Use Feed failed on size\r\n");
                        why = (unsigned char *)"Bad block size";
                        goto failure;
                }
                if (!VALIDKEY(krbdes_key)) {
                        if (encrypt_debug_mode)
                                printf("Use Feed failed on key\r\n");
                        why = (unsigned char *)"Invalid key";
                        goto failure;
                }
                if (encrypt_debug_mode)
                        printf("Have a Use Feed\r\n");

                bcopy((void *)data, (void *)b, sizeof(Block));
                des_ecb_encrypt(b, input_feed, krbdes_sched, 0);

                input_feed[0] ^= 'K';
                input_feed[1] ^= 'R';
                input_feed[2] ^= 'B';
                input_feed[3] ^= 'D';
                input_feed[4] ^= 'E';
                input_feed[5] ^= 'S';

                des_ecb_encrypt(input_feed, b, krbdes_sched, 1);
                str_feed[3] = ENCRYPT_REPLY;
                p = str_feed + 5;
                *p++ = KRBDES_FEED_VRFY;
                for (x = 0; x < sizeof(Block); ++x) {
                        if ((*p++ = b[x]) == IAC)
                                *p++ = IAC;
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &str_feed[2], p - &str_feed[2]);
                net_write(str_feed, p - str_feed);
                if (encrypt_debug_mode)
                        printf("Initializing Decrypt stream\r\n");
                key_stream_init(krbdes_key, input_feed, DIR_DECRYPT);
                state[DECRYPT_STATE] = IN_PROGRESS;
                return(IN_PROGRESS);

        case KRBDES_FEED_OK:
                state[DECRYPT_STATE] = SUCCESS;
                return(SUCCESS);

        case KRBDES_FEED_FAIL:
                state[DECRYPT_STATE] = FAILED;
                return(FAILED);

        default:
                if (encrypt_debug_mode) {
                        printf("Unknown option type: %d\r\n", data[-1]);
                        printd(data, cnt);
                        printf("\r\n");
                }
                why = (unsigned char *)"Unknown sub-suboption";
        failure:
                /*
                 * We failed.  Send an empty KRBDES_FEED_VRFY option
                 * to the other side so it will know that things
                 * failed.
                 */
                str_feed[3] = ENCRYPT_REPLY;
                p = str_feed + 5;
                *p++ = KRBDES_FEED_VRFY_FAIL;
                if (why) {
                        while (*why) {
                                if ((*p++ = *why++) == IAC)
                                        *p++ = IAC;
                        }
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &str_feed[2], p - &str_feed[2]);
                net_write(str_feed, p - str_feed);
                state[DECRYPT_STATE] = FAILED;
                return(FAILED);
        }
}

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

        int
krbdes_reply(data, cnt)
        unsigned char *data;
        int cnt;
{
        int x;
        unsigned char *p;
        unsigned char *why = 0;
        Block b;

        if (cnt-- < 1) {
                why = (unsigned char *)"Bad REPLY suboption";
                goto failure;
        }

        switch (*data++) {
        case KRBDES_FEED_VRFY:
                if (cnt != sizeof(Block)) {
                        if (encrypt_debug_mode)
                                printf("Have Feed failed on size\r\n");
                        why = (unsigned char *)"Bad block size";
                        goto failure;
                }
                if (!VALIDKEY(krbdes_key)) {
                        if (encrypt_debug_mode)
                                printf("Have Feed failed on key\r\n");
                        why = (unsigned char *)"Invalid key";
                        goto failure;
                }
                if (encrypt_debug_mode)
                        printf("Have a Test Feed\r\n");

                bcopy((void *)data, (void *)b, sizeof(Block));
                des_ecb_encrypt(b, output_feed, krbdes_sched, 0);
                if (!SAMEKEY(output_feed, temp_feed)) {
                        if (encrypt_debug_mode)
                                printf("Have Feed failed on challange\r\n");
                        bzero((void *)output_feed, sizeof(Block));
                        why = (unsigned char*)"Challange decrypt failed";
                        goto failure;
                }
                if (encrypt_debug_mode)
                        printf("Initializing Encrypt stream\r\n");
                key_stream_init(krbdes_key, output_feed, DIR_ENCRYPT);

                str_feed[3] = ENCRYPT_IS;
                p = str_feed + 5;
                *p++ = KRBDES_FEED_OK;
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &str_feed[2], p - &str_feed[2]);
                net_write(str_feed, p - str_feed);
                state[ENCRYPT_STATE] = SUCCESS;
                return(SUCCESS);

        default:
                if (encrypt_debug_mode) {
                        printf("Unknown option type: %d\r\n", data[-1]);
                        printd(data, cnt);
                        printf("\r\n");
                }
                why = (unsigned char *)"Unknown sub-suboption";
        failure:
                str_feed[3] = ENCRYPT_IS;
                p = str_feed + 5;
                *p++ = KRBDES_FEED_FAIL;
                if (why) {
                        while (*why) {
                                if ((*p++ = *why++) == IAC)
                                        *p++ = IAC;
                        }
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &str_feed[2], p - &str_feed[2]);
                net_write(str_feed, p - str_feed);
                state[ENCRYPT_STATE] = FAILED;
                return(FAILED);
        }
}

        void
krbdes_encrypt(s, c)
        unsigned char *s;
        int c;
{
        while (c-- > 0) {
                *s = key_stream(DIR_ENCRYPT, *s);
                ++s;
        }
}

        int
krbdes_decrypt(c)
        int c;
{
        return(key_stream(DIR_DECRYPT, c));
#ifdef  ndef

        if (c == -1) {
                ++use;
                return(0);
        }
        if (use) {
                use = 0;
        } else {
                last = key_stream(DIR_DECRYPT, c);
        }

        return(last ^ c);
#endif
}

        void
krbdes_session(key, server)
        Session_Key *key;
        int server;
{
        static once = 1;

        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;
        }
        bcopy((void *)key->data, (void *)krbdes_key, sizeof(Block));
        if (once) {
                des_set_random_generator_seed(krbdes_key);
                once = 0;
        }
        des_key_sched(krbdes_key, 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 (need_start) {
                krbdes_start(DIR_ENCRYPT, server);
                need_start = 0;
        }
}

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

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

        switch(data[2]) {
        case KRBDES_FEED_OK:
                cp = "FEED_OK";
                goto common1;
        case KRBDES_FEED_FAIL:
                cp = "FEED_FAIL";
        common1:
                for (; (buflen > 0) && (*buf = *cp++); buf++)
                        buflen--;
                if (cnt > 3) {
                        if (buflen <= 0)
                                break;
                        *buf++ = ' ';
                        if (--buflen <= 0)
                                break;
                        *buf++ = '"';
                        for (i = 3; i < cnt && buflen > 0; i++, buflen--)
                                *buf++ = data[i];
                        if (buflen <= 0)
                                break;
                        *buf++ = '"';
                        --buflen;
                }
                if (buflen <= 0)
                        break;
                *buf++ = '\0';
                break;

        case KRBDES_FEED_INIT:
                cp = "FEED_INIT ";
                goto common2;

        case KRBDES_FEED_VRFY:
                cp = "FEED_VRFY ";
                goto common2;

        default:
                sprintf(lbuf, " %d (unknown)", data[2]);
                cp = lbuf;
        common2:
                for (; (buflen > 0) && (*buf = *cp++); buf++)
                        buflen--;
                for (i = 3; i < cnt; i++) {
                        sprintf(lbuf, " %d", data[i]);
                        for (cp = lbuf; (buflen > 0) && (*buf = *cp++); buf++)
                                buflen--;
                }
                break;
        }
}

static  Block stream_output[2];
static  Block stream_feed[2];
static  Schedule stream_sched[2];
static  int stream_index[2];

        void
key_stream_init(key, seed, dir)
        Block key;
        Block seed;
        int dir;
{
        des_key_sched(key, stream_sched[--dir]);
        bcopy((void *)seed, (void *)stream_output[dir], sizeof(Block));
        stream_index[dir] = sizeof(Block);
}

        unsigned char
key_stream(dir, data)
        int dir;
        int data;       /* data de/encrypting */
{
        int index;

        if (data == -1) {
                /* Backpeddle */
                if (stream_index[--dir])
                        --stream_index[dir];
                return(0);
        }
        if ((index = stream_index[--dir]++) == sizeof(Block)) {
                Block b;
                des_ecb_encrypt(stream_output[dir],
                                b,
                                stream_sched[dir], 1);
                bcopy((void *)b, (void *)stream_feed[dir], sizeof(Block));
                stream_index[dir] = 1;  /* Next time will be 1 */
                index = 0;              /* But now use 0 */
        }

        /*
         * On encryption, we store (feed ^ data) which is cypher
         * On decryption we store (data) which is cypher
         */
        if (dir == DIR_DECRYPT)
                return(stream_output[dir][index] =
                        (stream_feed[dir][index] ^ data));
        else
                return((stream_output[dir][index] = data) ^
                          stream_feed[dir][index]);
}
#endif