1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <config.h>
35
36 RCSID("$Id$");
37
38 #if defined(AUTHENTICATION) && defined(ENCRYPTION) && defined(DES_ENCRYPTION)
39 #include <arpa/telnet.h>
40 #include <stdio.h>
41 #ifdef __STDC__
42 #include <stdlib.h>
43 #include <string.h>
44 #endif
45 #include <roken.h>
46 #ifdef SOCKS
47 #include <socks.h>
48 #endif
49
50 #include "encrypt.h"
51 #include "misc-proto.h"
52
53 #include "crypto-headers.h"
54
55 extern int encrypt_debug_mode;
56
57 #define CFB 0
58 #define OFB 1
59
60 #define NO_SEND_IV 1
61 #define NO_RECV_IV 2
62 #define NO_KEYID 4
63 #define IN_PROGRESS (NO_SEND_IV|NO_RECV_IV|NO_KEYID)
64 #define SUCCESS 0
65 #define FAILED -1
66
67
68 struct stinfo {
69 DES_cblock str_output;
70 DES_cblock str_feed;
71 DES_cblock str_iv;
72 DES_cblock str_ikey;
73 DES_key_schedule str_sched;
74 int str_index;
75 int str_flagshift;
76 };
77
78 struct fb {
79 DES_cblock krbdes_key;
80 DES_key_schedule krbdes_sched;
81 DES_cblock temp_feed;
82 unsigned char fb_feed[64];
83 int need_start;
84 int state[2];
85 int keyid[2];
86 struct stinfo streams[2];
87 };
88
89 static struct fb fb[2];
90
91 struct keyidlist {
92 char *keyid;
93 int keyidlen;
94 char *key;
95 int keylen;
96 int flags;
97 } keyidlist [] = {
98 { "\0", 1, 0, 0, 0 }, /* default key of zero */
99 { 0, 0, 0, 0, 0 }
100 };
101
102 #define KEYFLAG_MASK 03
103
104 #define KEYFLAG_NOINIT 00
105 #define KEYFLAG_INIT 01
106 #define KEYFLAG_OK 02
107 #define KEYFLAG_BAD 03
108
109 #define KEYFLAG_SHIFT 2
110
111 #define SHIFT_VAL(a,b) (KEYFLAG_SHIFT*((a)+((b)*2)))
112
113 #define FB64_IV 1
114 #define FB64_IV_OK 2
115 #define FB64_IV_BAD 3
116
117
118 void fb64_stream_iv (DES_cblock, struct stinfo *);
119 void fb64_init (struct fb *);
120 static int fb64_start (struct fb *, int, int);
121 int fb64_is (unsigned char *, int, struct fb *);
122 int fb64_reply (unsigned char *, int, struct fb *);
123 static void fb64_session (Session_Key *, int, struct fb *);
124 void fb64_stream_key (DES_cblock, struct stinfo *);
125 int fb64_keyid (int, unsigned char *, int *, struct fb *);
126 void fb64_printsub(unsigned char *, size_t ,
127 unsigned char *, size_t , char *);
128
cfb64_init(int server)129 void cfb64_init(int server)
130 {
131 fb64_init(&fb[CFB]);
132 fb[CFB].fb_feed[4] = ENCTYPE_DES_CFB64;
133 fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, CFB);
134 fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, CFB);
135 }
136
137
ofb64_init(int server)138 void ofb64_init(int server)
139 {
140 fb64_init(&fb[OFB]);
141 fb[OFB].fb_feed[4] = ENCTYPE_DES_OFB64;
142 fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, OFB);
143 fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, OFB);
144 }
145
fb64_init(struct fb * fbp)146 void fb64_init(struct fb *fbp)
147 {
148 memset(fbp,0, sizeof(*fbp));
149 fbp->state[0] = fbp->state[1] = FAILED;
150 fbp->fb_feed[0] = IAC;
151 fbp->fb_feed[1] = SB;
152 fbp->fb_feed[2] = TELOPT_ENCRYPT;
153 fbp->fb_feed[3] = ENCRYPT_IS;
154 }
155
156 /*
157 * Returns:
158 * -1: some error. Negotiation is done, encryption not ready.
159 * 0: Successful, initial negotiation all done.
160 * 1: successful, negotiation not done yet.
161 * 2: Not yet. Other things (like getting the key from
162 * Kerberos) have to happen before we can continue.
163 */
cfb64_start(int dir,int server)164 int cfb64_start(int dir, int server)
165 {
166 return(fb64_start(&fb[CFB], dir, server));
167 }
168
ofb64_start(int dir,int server)169 int ofb64_start(int dir, int server)
170 {
171 return(fb64_start(&fb[OFB], dir, server));
172 }
173
fb64_start(struct fb * fbp,int dir,int server)174 static int fb64_start(struct fb *fbp, int dir, int server)
175 {
176 int x;
177 unsigned char *p;
178 int state;
179
180 switch (dir) {
181 case DIR_DECRYPT:
182 /*
183 * This is simply a request to have the other side
184 * start output (our input). He will negotiate an
185 * IV so we need not look for it.
186 */
187 state = fbp->state[dir-1];
188 if (state == FAILED)
189 state = IN_PROGRESS;
190 break;
191
192 case DIR_ENCRYPT:
193 state = fbp->state[dir-1];
194 if (state == FAILED)
195 state = IN_PROGRESS;
196 else if ((state & NO_SEND_IV) == 0) {
197 break;
198 }
199
200 if (!VALIDKEY(fbp->krbdes_key)) {
201 fbp->need_start = 1;
202 break;
203 }
204
205 state &= ~NO_SEND_IV;
206 state |= NO_RECV_IV;
207 if (encrypt_debug_mode)
208 printf("Creating new feed\r\n");
209 /*
210 * Create a random feed and send it over.
211 */
212 do {
213 if (RAND_bytes(fbp->temp_feed,
214 sizeof(*fbp->temp_feed)) != 1)
215 abort();
216 DES_set_odd_parity(&fbp->temp_feed);
217 } while(DES_is_weak_key(&fbp->temp_feed));
218
219 p = fbp->fb_feed + 3;
220 *p++ = ENCRYPT_IS;
221 p++;
222 *p++ = FB64_IV;
223 for (x = 0; x < sizeof(DES_cblock); ++x) {
224 if ((*p++ = fbp->temp_feed[x]) == IAC)
225 *p++ = IAC;
226 }
227 *p++ = IAC;
228 *p++ = SE;
229 printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
230 telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);
231 break;
232 default:
233 return(FAILED);
234 }
235 return(fbp->state[dir-1] = state);
236 }
237
238 /*
239 * Returns:
240 * -1: some error. Negotiation is done, encryption not ready.
241 * 0: Successful, initial negotiation all done.
242 * 1: successful, negotiation not done yet.
243 */
244
cfb64_is(unsigned char * data,int cnt)245 int cfb64_is(unsigned char *data, int cnt)
246 {
247 return(fb64_is(data, cnt, &fb[CFB]));
248 }
249
ofb64_is(unsigned char * data,int cnt)250 int ofb64_is(unsigned char *data, int cnt)
251 {
252 return(fb64_is(data, cnt, &fb[OFB]));
253 }
254
255
fb64_is(unsigned char * data,int cnt,struct fb * fbp)256 int fb64_is(unsigned char *data, int cnt, struct fb *fbp)
257 {
258 unsigned char *p;
259 int state = fbp->state[DIR_DECRYPT-1];
260
261 if (cnt-- < 1)
262 goto failure;
263
264 switch (*data++) {
265 case FB64_IV:
266 if (cnt != sizeof(DES_cblock)) {
267 if (encrypt_debug_mode)
268 printf("CFB64: initial vector failed on size\r\n");
269 state = FAILED;
270 goto failure;
271 }
272
273 if (encrypt_debug_mode)
274 printf("CFB64: initial vector received\r\n");
275
276 if (encrypt_debug_mode)
277 printf("Initializing Decrypt stream\r\n");
278
279 fb64_stream_iv(data, &fbp->streams[DIR_DECRYPT-1]);
280
281 p = fbp->fb_feed + 3;
282 *p++ = ENCRYPT_REPLY;
283 p++;
284 *p++ = FB64_IV_OK;
285 *p++ = IAC;
286 *p++ = SE;
287 printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
288 telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);
289
290 state = fbp->state[DIR_DECRYPT-1] = IN_PROGRESS;
291 break;
292
293 default:
294 if (encrypt_debug_mode) {
295 printf("Unknown option type: %d\r\n", *(data-1));
296 printd(data, cnt);
297 printf("\r\n");
298 }
299 /* FALL THROUGH */
300 failure:
301 /*
302 * We failed. Send an FB64_IV_BAD option
303 * to the other side so it will know that
304 * things failed.
305 */
306 p = fbp->fb_feed + 3;
307 *p++ = ENCRYPT_REPLY;
308 p++;
309 *p++ = FB64_IV_BAD;
310 *p++ = IAC;
311 *p++ = SE;
312 printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
313 telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);
314
315 break;
316 }
317 return(fbp->state[DIR_DECRYPT-1] = state);
318 }
319
320 /*
321 * Returns:
322 * -1: some error. Negotiation is done, encryption not ready.
323 * 0: Successful, initial negotiation all done.
324 * 1: successful, negotiation not done yet.
325 */
326
cfb64_reply(unsigned char * data,int cnt)327 int cfb64_reply(unsigned char *data, int cnt)
328 {
329 return(fb64_reply(data, cnt, &fb[CFB]));
330 }
331
ofb64_reply(unsigned char * data,int cnt)332 int ofb64_reply(unsigned char *data, int cnt)
333 {
334 return(fb64_reply(data, cnt, &fb[OFB]));
335 }
336
337
fb64_reply(unsigned char * data,int cnt,struct fb * fbp)338 int fb64_reply(unsigned char *data, int cnt, struct fb *fbp)
339 {
340 int state = fbp->state[DIR_ENCRYPT-1];
341
342 if (cnt-- < 1)
343 goto failure;
344
345 switch (*data++) {
346 case FB64_IV_OK:
347 fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
348 if (state == FAILED)
349 state = IN_PROGRESS;
350 state &= ~NO_RECV_IV;
351 encrypt_send_keyid(DIR_ENCRYPT, (unsigned char *)"\0", 1, 1);
352 break;
353
354 case FB64_IV_BAD:
355 memset(fbp->temp_feed, 0, sizeof(DES_cblock));
356 fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
357 state = FAILED;
358 break;
359
360 default:
361 if (encrypt_debug_mode) {
362 printf("Unknown option type: %d\r\n", data[-1]);
363 printd(data, cnt);
364 printf("\r\n");
365 }
366 /* FALL THROUGH */
367 failure:
368 state = FAILED;
369 break;
370 }
371 return(fbp->state[DIR_ENCRYPT-1] = state);
372 }
373
cfb64_session(Session_Key * key,int server)374 void cfb64_session(Session_Key *key, int server)
375 {
376 fb64_session(key, server, &fb[CFB]);
377 }
378
ofb64_session(Session_Key * key,int server)379 void ofb64_session(Session_Key *key, int server)
380 {
381 fb64_session(key, server, &fb[OFB]);
382 }
383
fb64_session(Session_Key * key,int server,struct fb * fbp)384 static void fb64_session(Session_Key *key, int server, struct fb *fbp)
385 {
386
387 if (!key || key->type != SK_DES) {
388 if (encrypt_debug_mode)
389 printf("Can't set krbdes's session key (%d != %d)\r\n",
390 key ? key->type : -1, SK_DES);
391 return;
392 }
393 memcpy(fbp->krbdes_key, key->data, sizeof(DES_cblock));
394
395 fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_ENCRYPT-1]);
396 fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_DECRYPT-1]);
397
398 RAND_seed(key->data, key->length);
399
400 DES_set_key_checked((DES_cblock *)&fbp->krbdes_key,
401 &fbp->krbdes_sched);
402 /*
403 * Now look to see if krbdes_start() was waiting for the key to
404 * show up. If so, go ahead an call it now that we have the key.
405 */
406 if (fbp->need_start) {
407 fbp->need_start = 0;
408 fb64_start(fbp, DIR_ENCRYPT, server);
409 }
410 }
411
412 /*
413 * We only accept a keyid of 0. If we get a keyid of
414 * 0, then mark the state as SUCCESS.
415 */
416
cfb64_keyid(int dir,unsigned char * kp,int * lenp)417 int cfb64_keyid(int dir, unsigned char *kp, int *lenp)
418 {
419 return(fb64_keyid(dir, kp, lenp, &fb[CFB]));
420 }
421
ofb64_keyid(int dir,unsigned char * kp,int * lenp)422 int ofb64_keyid(int dir, unsigned char *kp, int *lenp)
423 {
424 return(fb64_keyid(dir, kp, lenp, &fb[OFB]));
425 }
426
fb64_keyid(int dir,unsigned char * kp,int * lenp,struct fb * fbp)427 int fb64_keyid(int dir, unsigned char *kp, int *lenp, struct fb *fbp)
428 {
429 int state = fbp->state[dir-1];
430
431 if (*lenp != 1 || (*kp != '\0')) {
432 *lenp = 0;
433 return(state);
434 }
435
436 if (state == FAILED)
437 state = IN_PROGRESS;
438
439 state &= ~NO_KEYID;
440
441 return(fbp->state[dir-1] = state);
442 }
443
fb64_printsub(unsigned char * data,size_t cnt,unsigned char * buf,size_t buflen,char * type)444 void fb64_printsub(unsigned char *data, size_t cnt,
445 unsigned char *buf, size_t buflen, char *type)
446 {
447 char lbuf[32];
448 int i;
449 char *cp;
450
451 buf[buflen-1] = '\0'; /* make sure it's NULL terminated */
452 buflen -= 1;
453
454 switch(data[2]) {
455 case FB64_IV:
456 snprintf(lbuf, sizeof(lbuf), "%s_IV", type);
457 cp = lbuf;
458 goto common;
459
460 case FB64_IV_OK:
461 snprintf(lbuf, sizeof(lbuf), "%s_IV_OK", type);
462 cp = lbuf;
463 goto common;
464
465 case FB64_IV_BAD:
466 snprintf(lbuf, sizeof(lbuf), "%s_IV_BAD", type);
467 cp = lbuf;
468 goto common;
469
470 default:
471 snprintf(lbuf, sizeof(lbuf), " %d (unknown)", data[2]);
472 cp = lbuf;
473 common:
474 for (; (buflen > 0) && (*buf = *cp++); buf++)
475 buflen--;
476 for (i = 3; i < cnt; i++) {
477 snprintf(lbuf, sizeof(lbuf), " %d", data[i]);
478 for (cp = lbuf; (buflen > 0) && (*buf = *cp++); buf++)
479 buflen--;
480 }
481 break;
482 }
483 }
484
cfb64_printsub(unsigned char * data,size_t cnt,unsigned char * buf,size_t buflen)485 void cfb64_printsub(unsigned char *data, size_t cnt,
486 unsigned char *buf, size_t buflen)
487 {
488 fb64_printsub(data, cnt, buf, buflen, "CFB64");
489 }
490
ofb64_printsub(unsigned char * data,size_t cnt,unsigned char * buf,size_t buflen)491 void ofb64_printsub(unsigned char *data, size_t cnt,
492 unsigned char *buf, size_t buflen)
493 {
494 fb64_printsub(data, cnt, buf, buflen, "OFB64");
495 }
496
fb64_stream_iv(DES_cblock seed,struct stinfo * stp)497 void fb64_stream_iv(DES_cblock seed, struct stinfo *stp)
498 {
499
500 memcpy(stp->str_iv, seed,sizeof(DES_cblock));
501 memcpy(stp->str_output, seed, sizeof(DES_cblock));
502
503 DES_set_key_checked(&stp->str_ikey, &stp->str_sched);
504
505 stp->str_index = sizeof(DES_cblock);
506 }
507
fb64_stream_key(DES_cblock key,struct stinfo * stp)508 void fb64_stream_key(DES_cblock key, struct stinfo *stp)
509 {
510 memcpy(stp->str_ikey, key, sizeof(DES_cblock));
511 DES_set_key_checked((DES_cblock*)key, &stp->str_sched);
512
513 memcpy(stp->str_output, stp->str_iv, sizeof(DES_cblock));
514
515 stp->str_index = sizeof(DES_cblock);
516 }
517
518 /*
519 * DES 64 bit Cipher Feedback
520 *
521 * key --->+-----+
522 * +->| DES |--+
523 * | +-----+ |
524 * | v
525 * INPUT --(--------->(+)+---> DATA
526 * | |
527 * +-------------+
528 *
529 *
530 * Given:
531 * iV: Initial vector, 64 bits (8 bytes) long.
532 * Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
533 * On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
534 *
535 * V0 = DES(iV, key)
536 * On = Dn ^ Vn
537 * V(n+1) = DES(On, key)
538 */
539
cfb64_encrypt(unsigned char * s,int c)540 void cfb64_encrypt(unsigned char *s, int c)
541 {
542 struct stinfo *stp = &fb[CFB].streams[DIR_ENCRYPT-1];
543 int index;
544
545 index = stp->str_index;
546 while (c-- > 0) {
547 if (index == sizeof(DES_cblock)) {
548 DES_cblock b;
549 DES_ecb_encrypt(&stp->str_output, &b,&stp->str_sched, 1);
550 memcpy(stp->str_feed, b, sizeof(DES_cblock));
551 index = 0;
552 }
553
554 /* On encryption, we store (feed ^ data) which is cypher */
555 *s = stp->str_output[index] = (stp->str_feed[index] ^ *s);
556 s++;
557 index++;
558 }
559 stp->str_index = index;
560 }
561
cfb64_decrypt(int data)562 int cfb64_decrypt(int data)
563 {
564 struct stinfo *stp = &fb[CFB].streams[DIR_DECRYPT-1];
565 int index;
566
567 if (data == -1) {
568 /*
569 * Back up one byte. It is assumed that we will
570 * never back up more than one byte. If we do, this
571 * may or may not work.
572 */
573 if (stp->str_index)
574 --stp->str_index;
575 return(0);
576 }
577
578 index = stp->str_index++;
579 if (index == sizeof(DES_cblock)) {
580 DES_cblock b;
581 DES_ecb_encrypt(&stp->str_output,&b, &stp->str_sched, 1);
582 memcpy(stp->str_feed, b, sizeof(DES_cblock));
583 stp->str_index = 1; /* Next time will be 1 */
584 index = 0; /* But now use 0 */
585 }
586
587 /* On decryption we store (data) which is cypher. */
588 stp->str_output[index] = data;
589 return(data ^ stp->str_feed[index]);
590 }
591
592 /*
593 * DES 64 bit Output Feedback
594 *
595 * key --->+-----+
596 * +->| DES |--+
597 * | +-----+ |
598 * +-----------+
599 * v
600 * INPUT -------->(+) ----> DATA
601 *
602 * Given:
603 * iV: Initial vector, 64 bits (8 bytes) long.
604 * Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
605 * On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
606 *
607 * V0 = DES(iV, key)
608 * V(n+1) = DES(Vn, key)
609 * On = Dn ^ Vn
610 */
611
ofb64_encrypt(unsigned char * s,int c)612 void ofb64_encrypt(unsigned char *s, int c)
613 {
614 struct stinfo *stp = &fb[OFB].streams[DIR_ENCRYPT-1];
615 int index;
616
617 index = stp->str_index;
618 while (c-- > 0) {
619 if (index == sizeof(DES_cblock)) {
620 DES_cblock b;
621 DES_ecb_encrypt(&stp->str_feed,&b, &stp->str_sched, 1);
622 memcpy(stp->str_feed, b, sizeof(DES_cblock));
623 index = 0;
624 }
625 *s++ ^= stp->str_feed[index];
626 index++;
627 }
628 stp->str_index = index;
629 }
630
ofb64_decrypt(int data)631 int ofb64_decrypt(int data)
632 {
633 struct stinfo *stp = &fb[OFB].streams[DIR_DECRYPT-1];
634 int index;
635
636 if (data == -1) {
637 /*
638 * Back up one byte. It is assumed that we will
639 * never back up more than one byte. If we do, this
640 * may or may not work.
641 */
642 if (stp->str_index)
643 --stp->str_index;
644 return(0);
645 }
646
647 index = stp->str_index++;
648 if (index == sizeof(DES_cblock)) {
649 DES_cblock b;
650 DES_ecb_encrypt(&stp->str_feed,&b,&stp->str_sched, 1);
651 memcpy(stp->str_feed, b, sizeof(DES_cblock));
652 stp->str_index = 1; /* Next time will be 1 */
653 index = 0; /* But now use 0 */
654 }
655
656 return(data ^ stp->str_feed[index]);
657 }
658 #endif
659
660