xref: /freebsd/contrib/telnet/libtelnet/encrypt.c (revision c1b2af731bbdd6f37d0f75386acab31b5ad86090)
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. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 
32 __FBSDID("$FreeBSD$");
33 
34 #ifndef lint
35 #if 0
36 static const char sccsid[] = "@(#)encrypt.c	8.2 (Berkeley) 5/30/95";
37 #endif
38 #endif /* not lint */
39 
40 /*
41  * Copyright (C) 1990 by the Massachusetts Institute of Technology
42  *
43  * Export of this software from the United States of America is assumed
44  * to require a specific license from the United States Government.
45  * It is the responsibility of any person or organization contemplating
46  * export to obtain such a license before exporting.
47  *
48  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
49  * distribute this software and its documentation for any purpose and
50  * without fee is hereby granted, provided that the above copyright
51  * notice appear in all copies and that both that copyright notice and
52  * this permission notice appear in supporting documentation, and that
53  * the name of M.I.T. not be used in advertising or publicity pertaining
54  * to distribution of the software without specific, written prior
55  * permission.  M.I.T. makes no representations about the suitability of
56  * this software for any purpose.  It is provided "as is" without express
57  * or implied warranty.
58  */
59 
60 #ifdef	ENCRYPTION
61 
62 #include <sys/types.h>
63 #define	ENCRYPT_NAMES
64 #include <arpa/telnet.h>
65 #include <stdio.h>
66 #include <stdlib.h>
67 #include <string.h>
68 
69 #include "encrypt.h"
70 #include "misc.h"
71 
72 int EncryptType(char *type, char *mode);
73 int EncryptStart(char *mode);
74 int EncryptStop(char *mode);
75 int EncryptStartInput(void);
76 int EncryptStartOutput(void);
77 int EncryptStopInput(void);
78 int EncryptStopOutput(void);
79 
80 int encrypt_debug_mode = 0;
81 static int decrypt_mode = 0;
82 static int encrypt_mode = 0;
83 static int encrypt_verbose = 0;
84 static int autoencrypt = 0;
85 static int autodecrypt = 0;
86 static int havesessionkey = 0;
87 static int Server = 0;
88 static const char *Name = "Noname";
89 
90 #define	typemask(x)	((x) > 0 ? 1 << ((x)-1) : 0)
91 
92 static u_long i_support_encrypt = 0
93  | typemask(ENCTYPE_DES_CFB64) | typemask(ENCTYPE_DES_OFB64)
94  |0;
95 static u_long i_support_decrypt = 0
96  | typemask(ENCTYPE_DES_CFB64) | typemask(ENCTYPE_DES_OFB64)
97  |0;
98 
99 static u_long i_wont_support_encrypt = 0;
100 static u_long i_wont_support_decrypt = 0;
101 #define	I_SUPPORT_ENCRYPT	(i_support_encrypt & ~i_wont_support_encrypt)
102 #define	I_SUPPORT_DECRYPT	(i_support_decrypt & ~i_wont_support_decrypt)
103 
104 static u_long remote_supports_encrypt = 0;
105 static u_long remote_supports_decrypt = 0;
106 
107 static Encryptions encryptions[] = {
108     { "DES_CFB64",	ENCTYPE_DES_CFB64,
109 			cfb64_encrypt,
110 			cfb64_decrypt,
111 			cfb64_init,
112 			cfb64_start,
113 			cfb64_is,
114 			cfb64_reply,
115 			cfb64_session,
116 			cfb64_keyid,
117 			cfb64_printsub },
118     { "DES_OFB64",	ENCTYPE_DES_OFB64,
119 			ofb64_encrypt,
120 			ofb64_decrypt,
121 			ofb64_init,
122 			ofb64_start,
123 			ofb64_is,
124 			ofb64_reply,
125 			ofb64_session,
126 			ofb64_keyid,
127 			ofb64_printsub },
128     { NULL, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
129 };
130 
131 static unsigned char str_send[64] = { IAC, SB, TELOPT_ENCRYPT,
132 					 ENCRYPT_SUPPORT };
133 static unsigned char str_suplen = 0;
134 static unsigned char str_start[72] = { IAC, SB, TELOPT_ENCRYPT };
135 static unsigned char str_end[] = { IAC, SB, TELOPT_ENCRYPT, 0, IAC, SE };
136 
137 Encryptions *
138 findencryption(int type)
139 {
140 	Encryptions *ep = encryptions;
141 
142 	if (!(I_SUPPORT_ENCRYPT & remote_supports_decrypt & (unsigned)typemask(type)))
143 		return(0);
144 	while (ep->type && ep->type != type)
145 		++ep;
146 	return(ep->type ? ep : 0);
147 }
148 
149 static Encryptions *
150 finddecryption(int type)
151 {
152 	Encryptions *ep = encryptions;
153 
154 	if (!(I_SUPPORT_DECRYPT & remote_supports_encrypt & (unsigned)typemask(type)))
155 		return(0);
156 	while (ep->type && ep->type != type)
157 		++ep;
158 	return(ep->type ? ep : 0);
159 }
160 
161 #define	MAXKEYLEN 64
162 
163 static struct key_info {
164 	unsigned char keyid[MAXKEYLEN];
165 	int keylen;
166 	int dir;
167 	int *modep;
168 	Encryptions *(*getcrypt)(int);
169 } ki[2] = {
170 	{ { 0 }, 0, DIR_ENCRYPT, &encrypt_mode, findencryption },
171 	{ { 0 }, 0, DIR_DECRYPT, &decrypt_mode, finddecryption },
172 };
173 
174 static void encrypt_keyid(struct key_info *kp, unsigned char *keyid, int len);
175 
176 void
177 encrypt_init(const char *name, int server)
178 {
179 	Encryptions *ep = encryptions;
180 
181 	Name = name;
182 	Server = server;
183 	i_support_encrypt = i_support_decrypt = 0;
184 	remote_supports_encrypt = remote_supports_decrypt = 0;
185 	encrypt_mode = 0;
186 	decrypt_mode = 0;
187 	encrypt_output = 0;
188 	decrypt_input = 0;
189 
190 	str_suplen = 4;
191 
192 	while (ep->type) {
193 		if (encrypt_debug_mode)
194 			printf(">>>%s: I will support %s\r\n",
195 				Name, ENCTYPE_NAME(ep->type));
196 		i_support_encrypt |= typemask(ep->type);
197 		i_support_decrypt |= typemask(ep->type);
198 		if ((i_wont_support_decrypt & typemask(ep->type)) == 0)
199 			if ((str_send[str_suplen++] = ep->type) == IAC)
200 				str_send[str_suplen++] = IAC;
201 		if (ep->init)
202 			(*ep->init)(Server);
203 		++ep;
204 	}
205 	str_send[str_suplen++] = IAC;
206 	str_send[str_suplen++] = SE;
207 }
208 
209 static void
210 encrypt_list_types(void)
211 {
212 	Encryptions *ep = encryptions;
213 
214 	printf("Valid encryption types:\n");
215 	while (ep->type) {
216 		printf("\t%s (%d)\r\n", ENCTYPE_NAME(ep->type), ep->type);
217 		++ep;
218 	}
219 }
220 
221 int
222 EncryptEnable(char *type, char *mode)
223 {
224 	if (isprefix(type, "help") || isprefix(type, "?")) {
225 		printf("Usage: encrypt enable <type> [input|output]\n");
226 		encrypt_list_types();
227 		return(0);
228 	}
229 	if (EncryptType(type, mode))
230 		return(EncryptStart(mode));
231 	return(0);
232 }
233 
234 int
235 EncryptDisable(char *type, char *mode)
236 {
237 	Encryptions *ep;
238 	int ret = 0;
239 
240 	if (isprefix(type, "help") || isprefix(type, "?")) {
241 		printf("Usage: encrypt disable <type> [input|output]\n");
242 		encrypt_list_types();
243 	} else if ((ep = (Encryptions *)genget(type, (char **)encryptions,
244 						sizeof(Encryptions))) == 0) {
245 		printf("%s: invalid encryption type\n", type);
246 	} else if (Ambiguous((char **)ep)) {
247 		printf("Ambiguous type '%s'\n", type);
248 	} else {
249 		if ((mode == 0) || (isprefix(mode, "input") ? 1 : 0)) {
250 			if (decrypt_mode == ep->type)
251 				EncryptStopInput();
252 			i_wont_support_decrypt |= typemask(ep->type);
253 			ret = 1;
254 		}
255 		if ((mode == 0) || (isprefix(mode, "output"))) {
256 			if (encrypt_mode == ep->type)
257 				EncryptStopOutput();
258 			i_wont_support_encrypt |= typemask(ep->type);
259 			ret = 1;
260 		}
261 		if (ret == 0)
262 			printf("%s: invalid encryption mode\n", mode);
263 	}
264 	return(ret);
265 }
266 
267 int
268 EncryptType(char *type, char *mode)
269 {
270 	Encryptions *ep;
271 	int ret = 0;
272 
273 	if (isprefix(type, "help") || isprefix(type, "?")) {
274 		printf("Usage: encrypt type <type> [input|output]\n");
275 		encrypt_list_types();
276 	} else if ((ep = (Encryptions *)genget(type, (char **)encryptions,
277 						sizeof(Encryptions))) == 0) {
278 		printf("%s: invalid encryption type\n", type);
279 	} else if (Ambiguous((char **)ep)) {
280 		printf("Ambiguous type '%s'\n", type);
281 	} else {
282 		if ((mode == 0) || isprefix(mode, "input")) {
283 			decrypt_mode = ep->type;
284 			i_wont_support_decrypt &= ~typemask(ep->type);
285 			ret = 1;
286 		}
287 		if ((mode == 0) || isprefix(mode, "output")) {
288 			encrypt_mode = ep->type;
289 			i_wont_support_encrypt &= ~typemask(ep->type);
290 			ret = 1;
291 		}
292 		if (ret == 0)
293 			printf("%s: invalid encryption mode\n", mode);
294 	}
295 	return(ret);
296 }
297 
298 int
299 EncryptStart(char *mode)
300 {
301 	int ret = 0;
302 	if (mode) {
303 		if (isprefix(mode, "input"))
304 			return(EncryptStartInput());
305 		if (isprefix(mode, "output"))
306 			return(EncryptStartOutput());
307 		if (isprefix(mode, "help") || isprefix(mode, "?")) {
308 			printf("Usage: encrypt start [input|output]\n");
309 			return(0);
310 		}
311 		printf("%s: invalid encryption mode 'encrypt start ?' for help\n", mode);
312 		return(0);
313 	}
314 	ret += EncryptStartInput();
315 	ret += EncryptStartOutput();
316 	return(ret);
317 }
318 
319 int
320 EncryptStartInput(void)
321 {
322 	if (decrypt_mode) {
323 		encrypt_send_request_start();
324 		return(1);
325 	}
326 	printf("No previous decryption mode, decryption not enabled\r\n");
327 	return(0);
328 }
329 
330 int
331 EncryptStartOutput(void)
332 {
333 	if (encrypt_mode) {
334 		encrypt_start_output(encrypt_mode);
335 		return(1);
336 	}
337 	printf("No previous encryption mode, encryption not enabled\r\n");
338 	return(0);
339 }
340 
341 int
342 EncryptStop(char *mode)
343 {
344 	int ret = 0;
345 	if (mode) {
346 		if (isprefix(mode, "input"))
347 			return(EncryptStopInput());
348 		if (isprefix(mode, "output"))
349 			return(EncryptStopOutput());
350 		if (isprefix(mode, "help") || isprefix(mode, "?")) {
351 			printf("Usage: encrypt stop [input|output]\n");
352 			return(0);
353 		}
354 		printf("%s: invalid encryption mode 'encrypt stop ?' for help\n", mode);
355 		return(0);
356 	}
357 	ret += EncryptStopInput();
358 	ret += EncryptStopOutput();
359 	return(ret);
360 }
361 
362 int
363 EncryptStopInput(void)
364 {
365 	encrypt_send_request_end();
366 	return(1);
367 }
368 
369 int
370 EncryptStopOutput(void)
371 {
372 	encrypt_send_end();
373 	return(1);
374 }
375 
376 void
377 encrypt_display(void)
378 {
379 	if (encrypt_output)
380 		printf("Currently encrypting output with %s\r\n",
381 			ENCTYPE_NAME(encrypt_mode));
382 	if (decrypt_input)
383 		printf("Currently decrypting input with %s\r\n",
384 			ENCTYPE_NAME(decrypt_mode));
385 }
386 
387 int
388 EncryptStatus(void)
389 {
390 	if (encrypt_output)
391 		printf("Currently encrypting output with %s\r\n",
392 			ENCTYPE_NAME(encrypt_mode));
393 	else if (encrypt_mode) {
394 		printf("Currently output is clear text.\r\n");
395 		printf("Last encryption mode was %s\r\n",
396 			ENCTYPE_NAME(encrypt_mode));
397 	}
398 	if (decrypt_input) {
399 		printf("Currently decrypting input with %s\r\n",
400 			ENCTYPE_NAME(decrypt_mode));
401 	} else if (decrypt_mode) {
402 		printf("Currently input is clear text.\r\n");
403 		printf("Last decryption mode was %s\r\n",
404 			ENCTYPE_NAME(decrypt_mode));
405 	}
406 	return 1;
407 }
408 
409 void
410 encrypt_send_support(void)
411 {
412 	if (str_suplen) {
413 		/*
414 		 * If the user has requested that decryption start
415 		 * immediatly, then send a "REQUEST START" before
416 		 * we negotiate the type.
417 		 */
418 		if (!Server && autodecrypt)
419 			encrypt_send_request_start();
420 		net_write(str_send, str_suplen);
421 		printsub('>', &str_send[2], str_suplen - 2);
422 		str_suplen = 0;
423 	}
424 }
425 
426 int
427 EncryptDebug(int on)
428 {
429 	if (on < 0)
430 		encrypt_debug_mode ^= 1;
431 	else
432 		encrypt_debug_mode = on;
433 	printf("Encryption debugging %s\r\n",
434 		encrypt_debug_mode ? "enabled" : "disabled");
435 	return(1);
436 }
437 
438 int
439 EncryptVerbose(int on)
440 {
441 	if (on < 0)
442 		encrypt_verbose ^= 1;
443 	else
444 		encrypt_verbose = on;
445 	printf("Encryption %s verbose\r\n",
446 		encrypt_verbose ? "is" : "is not");
447 	return(1);
448 }
449 
450 int
451 EncryptAutoEnc(int on)
452 {
453 	encrypt_auto(on);
454 	printf("Automatic encryption of output is %s\r\n",
455 		autoencrypt ? "enabled" : "disabled");
456 	return(1);
457 }
458 
459 int
460 EncryptAutoDec(int on)
461 {
462 	decrypt_auto(on);
463 	printf("Automatic decryption of input is %s\r\n",
464 		autodecrypt ? "enabled" : "disabled");
465 	return(1);
466 }
467 
468 /*
469  * Called when ENCRYPT SUPPORT is received.
470  */
471 void
472 encrypt_support(unsigned char *typelist, int cnt)
473 {
474 	int type, use_type = 0;
475 	Encryptions *ep;
476 
477 	/*
478 	 * Forget anything the other side has previously told us.
479 	 */
480 	remote_supports_decrypt = 0;
481 
482 	while (cnt-- > 0) {
483 		type = *typelist++;
484 		if (encrypt_debug_mode)
485 			printf(">>>%s: He is supporting %s (%d)\r\n",
486 				Name,
487 				ENCTYPE_NAME(type), type);
488 		if ((type < ENCTYPE_CNT) &&
489 		    (I_SUPPORT_ENCRYPT & typemask(type))) {
490 			remote_supports_decrypt |= typemask(type);
491 			if (use_type == 0)
492 				use_type = type;
493 		}
494 	}
495 	if (use_type) {
496 		ep = findencryption(use_type);
497 		if (!ep)
498 			return;
499 		type = ep->start ? (*ep->start)(DIR_ENCRYPT, Server) : 0;
500 		if (encrypt_debug_mode)
501 			printf(">>>%s: (*ep->start)() returned %d\r\n",
502 					Name, type);
503 		if (type < 0)
504 			return;
505 		encrypt_mode = use_type;
506 		if (type == 0)
507 			encrypt_start_output(use_type);
508 	}
509 }
510 
511 void
512 encrypt_is(unsigned char *data, int cnt)
513 {
514 	Encryptions *ep;
515 	int type, ret;
516 
517 	if (--cnt < 0)
518 		return;
519 	type = *data++;
520 	if (type < ENCTYPE_CNT)
521 		remote_supports_encrypt |= typemask(type);
522 	if (!(ep = finddecryption(type))) {
523 		if (encrypt_debug_mode)
524 			printf(">>>%s: Can't find type %s (%d) for initial negotiation\r\n",
525 				Name,
526 				ENCTYPE_NAME_OK(type)
527 					? ENCTYPE_NAME(type) : "(unknown)",
528 				type);
529 		return;
530 	}
531 	if (!ep->is) {
532 		if (encrypt_debug_mode)
533 			printf(">>>%s: No initial negotiation needed for type %s (%d)\r\n",
534 				Name,
535 				ENCTYPE_NAME_OK(type)
536 					? ENCTYPE_NAME(type) : "(unknown)",
537 				type);
538 		ret = 0;
539 	} else {
540 		ret = (*ep->is)(data, cnt);
541 		if (encrypt_debug_mode)
542 			printf("(*ep->is)(%p, %d) returned %s(%d)\n", data, cnt,
543 				(ret < 0) ? "FAIL " :
544 				(ret == 0) ? "SUCCESS " : "MORE_TO_DO ", ret);
545 	}
546 	if (ret < 0) {
547 		autodecrypt = 0;
548 	} else {
549 		decrypt_mode = type;
550 		if (ret == 0 && autodecrypt)
551 			encrypt_send_request_start();
552 	}
553 }
554 
555 void
556 encrypt_reply(unsigned char *data, int cnt)
557 {
558 	Encryptions *ep;
559 	int ret, type;
560 
561 	if (--cnt < 0)
562 		return;
563 	type = *data++;
564 	if (!(ep = findencryption(type))) {
565 		if (encrypt_debug_mode)
566 			printf(">>>%s: Can't find type %s (%d) for initial negotiation\r\n",
567 				Name,
568 				ENCTYPE_NAME_OK(type)
569 					? ENCTYPE_NAME(type) : "(unknown)",
570 				type);
571 		return;
572 	}
573 	if (!ep->reply) {
574 		if (encrypt_debug_mode)
575 			printf(">>>%s: No initial negotiation needed for type %s (%d)\r\n",
576 				Name,
577 				ENCTYPE_NAME_OK(type)
578 					? ENCTYPE_NAME(type) : "(unknown)",
579 				type);
580 		ret = 0;
581 	} else {
582 		ret = (*ep->reply)(data, cnt);
583 		if (encrypt_debug_mode)
584 			printf("(*ep->reply)(%p, %d) returned %s(%d)\n",
585 				data, cnt,
586 				(ret < 0) ? "FAIL " :
587 				(ret == 0) ? "SUCCESS " : "MORE_TO_DO ", ret);
588 	}
589 	if (encrypt_debug_mode)
590 		printf(">>>%s: encrypt_reply returned %d\n", Name, ret);
591 	if (ret < 0) {
592 		autoencrypt = 0;
593 	} else {
594 		encrypt_mode = type;
595 		if (ret == 0 && autoencrypt)
596 			encrypt_start_output(type);
597 	}
598 }
599 
600 /*
601  * Called when a ENCRYPT START command is received.
602  */
603 void
604 encrypt_start(unsigned char *data __unused, int cnt __unused)
605 {
606 	Encryptions *ep;
607 
608 	if (!decrypt_mode) {
609 		/*
610 		 * Something is wrong.  We should not get a START
611 		 * command without having already picked our
612 		 * decryption scheme.  Send a REQUEST-END to
613 		 * attempt to clear the channel...
614 		 */
615 		printf("%s: Warning, Cannot decrypt input stream!!!\r\n", Name);
616 		encrypt_send_request_end();
617 		return;
618 	}
619 
620 	if ((ep = finddecryption(decrypt_mode))) {
621 		decrypt_input = ep->input;
622 		if (encrypt_verbose)
623 			printf("[ Input is now decrypted with type %s ]\r\n",
624 				ENCTYPE_NAME(decrypt_mode));
625 		if (encrypt_debug_mode)
626 			printf(">>>%s: Start to decrypt input with type %s\r\n",
627 				Name, ENCTYPE_NAME(decrypt_mode));
628 	} else {
629 		printf("%s: Warning, Cannot decrypt type %s (%d)!!!\r\n",
630 				Name,
631 				ENCTYPE_NAME_OK(decrypt_mode)
632 					? ENCTYPE_NAME(decrypt_mode)
633 					: "(unknown)",
634 				decrypt_mode);
635 		encrypt_send_request_end();
636 	}
637 }
638 
639 void
640 encrypt_session_key( Session_Key *key, int server)
641 {
642 	Encryptions *ep = encryptions;
643 
644 	havesessionkey = 1;
645 
646 	while (ep->type) {
647 		if (ep->session)
648 			(*ep->session)(key, server);
649 		++ep;
650 	}
651 }
652 
653 /*
654  * Called when ENCRYPT END is received.
655  */
656 void
657 encrypt_end(void)
658 {
659 	decrypt_input = 0;
660 	if (encrypt_debug_mode)
661 		printf(">>>%s: Input is back to clear text\r\n", Name);
662 	if (encrypt_verbose)
663 		printf("[ Input is now clear text ]\r\n");
664 }
665 
666 /*
667  * Called when ENCRYPT REQUEST-END is received.
668  */
669 void
670 encrypt_request_end(void)
671 {
672 	encrypt_send_end();
673 }
674 
675 /*
676  * Called when ENCRYPT REQUEST-START is received.  If we receive
677  * this before a type is picked, then that indicates that the
678  * other side wants us to start encrypting data as soon as we
679  * can.
680  */
681 void
682 encrypt_request_start(unsigned char *data __unused, int cnt __unused)
683 {
684 	if (encrypt_mode == 0)  {
685 		if (Server)
686 			autoencrypt = 1;
687 		return;
688 	}
689 	encrypt_start_output(encrypt_mode);
690 }
691 
692 static unsigned char str_keyid[(MAXKEYLEN*2)+5] = { IAC, SB, TELOPT_ENCRYPT };
693 
694 void
695 encrypt_enc_keyid(unsigned char *keyid, int len)
696 {
697 	encrypt_keyid(&ki[1], keyid, len);
698 }
699 
700 void
701 encrypt_dec_keyid(unsigned char *keyid, int len)
702 {
703 	encrypt_keyid(&ki[0], keyid, len);
704 }
705 
706 void
707 encrypt_keyid(struct key_info *kp, unsigned char *keyid, int len)
708 {
709 	Encryptions *ep;
710 	int dir = kp->dir;
711 	int ret = 0;
712 
713 	if (len > MAXKEYLEN)
714 		len = MAXKEYLEN;
715 
716 	if (!(ep = (*kp->getcrypt)(*kp->modep))) {
717 		if (len == 0)
718 			return;
719 		kp->keylen = 0;
720 	} else if (len == 0) {
721 		/*
722 		 * Empty option, indicates a failure.
723 		 */
724 		if (kp->keylen == 0)
725 			return;
726 		kp->keylen = 0;
727 		if (ep->keyid)
728 			(void)(*ep->keyid)(dir, kp->keyid, &kp->keylen);
729 
730 	} else if ((len != kp->keylen) ||
731 		   (memcmp(keyid, kp->keyid, len) != 0)) {
732 		/*
733 		 * Length or contents are different
734 		 */
735 		kp->keylen = len;
736 		memmove(kp->keyid, keyid, len);
737 		if (ep->keyid)
738 			(void)(*ep->keyid)(dir, kp->keyid, &kp->keylen);
739 	} else {
740 		if (ep->keyid)
741 			ret = (*ep->keyid)(dir, kp->keyid, &kp->keylen);
742 		if ((ret == 0) && (dir == DIR_ENCRYPT) && autoencrypt)
743 			encrypt_start_output(*kp->modep);
744 		return;
745 	}
746 
747 	encrypt_send_keyid(dir, kp->keyid, kp->keylen, 0);
748 }
749 
750 void
751 encrypt_send_keyid(int dir, const char *keyid, int keylen, int saveit)
752 {
753 	unsigned char *strp;
754 
755 	str_keyid[3] = (dir == DIR_ENCRYPT)
756 			? ENCRYPT_ENC_KEYID : ENCRYPT_DEC_KEYID;
757 	if (saveit) {
758 		struct key_info *kp = &ki[(dir == DIR_ENCRYPT) ? 0 : 1];
759 		memmove(kp->keyid, keyid, keylen);
760 		kp->keylen = keylen;
761 	}
762 
763 	for (strp = &str_keyid[4]; keylen > 0; --keylen) {
764 		if ((*strp++ = *keyid++) == IAC)
765 			*strp++ = IAC;
766 	}
767 	*strp++ = IAC;
768 	*strp++ = SE;
769 	net_write(str_keyid, strp - str_keyid);
770 	printsub('>', &str_keyid[2], strp - str_keyid - 2);
771 }
772 
773 void
774 encrypt_auto(int on)
775 {
776 	if (on < 0)
777 		autoencrypt ^= 1;
778 	else
779 		autoencrypt = on ? 1 : 0;
780 }
781 
782 void
783 decrypt_auto(int on)
784 {
785 	if (on < 0)
786 		autodecrypt ^= 1;
787 	else
788 		autodecrypt = on ? 1 : 0;
789 }
790 
791 void
792 encrypt_start_output(int type)
793 {
794 	Encryptions *ep;
795 	unsigned char *p;
796 	int i;
797 
798 	if (!(ep = findencryption(type))) {
799 		if (encrypt_debug_mode) {
800 			printf(">>>%s: Can't encrypt with type %s (%d)\r\n",
801 				Name,
802 				ENCTYPE_NAME_OK(type)
803 					? ENCTYPE_NAME(type) : "(unknown)",
804 				type);
805 		}
806 		return;
807 	}
808 	if (ep->start) {
809 		i = (*ep->start)(DIR_ENCRYPT, Server);
810 		if (encrypt_debug_mode) {
811 			printf(">>>%s: Encrypt start: %s (%d) %s\r\n",
812 				Name,
813 				(i < 0) ? "failed" :
814 					"initial negotiation in progress",
815 				i, ENCTYPE_NAME(type));
816 		}
817 		if (i)
818 			return;
819 	}
820 	p = str_start + 3;
821 	*p++ = ENCRYPT_START;
822 	for (i = 0; i < ki[0].keylen; ++i) {
823 		if ((*p++ = ki[0].keyid[i]) == IAC)
824 			*p++ = IAC;
825 	}
826 	*p++ = IAC;
827 	*p++ = SE;
828 	net_write(str_start, p - str_start);
829 	net_encrypt();
830 	printsub('>', &str_start[2], p - &str_start[2]);
831 	/*
832 	 * If we are already encrypting in some mode, then
833 	 * encrypt the ring (which includes our request) in
834 	 * the old mode, mark it all as "clear text" and then
835 	 * switch to the new mode.
836 	 */
837 	encrypt_output = ep->output;
838 	encrypt_mode = type;
839 	if (encrypt_debug_mode)
840 		printf(">>>%s: Started to encrypt output with type %s\r\n",
841 			Name, ENCTYPE_NAME(type));
842 	if (encrypt_verbose)
843 		printf("[ Output is now encrypted with type %s ]\r\n",
844 			ENCTYPE_NAME(type));
845 }
846 
847 void
848 encrypt_send_end(void)
849 {
850 	if (!encrypt_output)
851 		return;
852 
853 	str_end[3] = ENCRYPT_END;
854 	net_write(str_end, sizeof(str_end));
855 	net_encrypt();
856 	printsub('>', &str_end[2], sizeof(str_end) - 2);
857 	/*
858 	 * Encrypt the output buffer now because it will not be done by
859 	 * netflush...
860 	 */
861 	encrypt_output = 0;
862 	if (encrypt_debug_mode)
863 		printf(">>>%s: Output is back to clear text\r\n", Name);
864 	if (encrypt_verbose)
865 		printf("[ Output is now clear text ]\r\n");
866 }
867 
868 void
869 encrypt_send_request_start(void)
870 {
871 	unsigned char *p;
872 	int i;
873 
874 	p = &str_start[3];
875 	*p++ = ENCRYPT_REQSTART;
876 	for (i = 0; i < ki[1].keylen; ++i) {
877 		if ((*p++ = ki[1].keyid[i]) == IAC)
878 			*p++ = IAC;
879 	}
880 	*p++ = IAC;
881 	*p++ = SE;
882 	net_write(str_start, p - str_start);
883 	printsub('>', &str_start[2], p - &str_start[2]);
884 	if (encrypt_debug_mode)
885 		printf(">>>%s: Request input to be encrypted\r\n", Name);
886 }
887 
888 void
889 encrypt_send_request_end(void)
890 {
891 	str_end[3] = ENCRYPT_REQEND;
892 	net_write(str_end, sizeof(str_end));
893 	printsub('>', &str_end[2], sizeof(str_end) - 2);
894 
895 	if (encrypt_debug_mode)
896 		printf(">>>%s: Request input to be clear text\r\n", Name);
897 }
898 
899 void
900 encrypt_wait(void)
901 {
902 	if (encrypt_debug_mode)
903 		printf(">>>%s: in encrypt_wait\r\n", Name);
904 	if (!havesessionkey || !(I_SUPPORT_ENCRYPT & remote_supports_decrypt))
905 		return;
906 	while (autoencrypt && !encrypt_output)
907 		if (telnet_spin())
908 			return;
909 }
910 
911 void
912 encrypt_gen_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
913 {
914 	char tbuf[16], *cp;
915 
916 	cnt -= 2;
917 	data += 2;
918 	buf[buflen-1] = '\0';
919 	buf[buflen-2] = '*';
920 	buflen -= 2;;
921 	for (; cnt > 0; cnt--, data++) {
922 		sprintf(tbuf, " %d", *data);
923 		for (cp = tbuf; *cp && buflen > 0; --buflen)
924 			*buf++ = *cp++;
925 		if (buflen <= 0)
926 			return;
927 	}
928 	*buf = '\0';
929 }
930 
931 void
932 encrypt_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
933 {
934 	Encryptions *ep;
935 	int type = data[1];
936 
937 	for (ep = encryptions; ep->type && ep->type != type; ep++)
938 		;
939 
940 	if (ep->printsub)
941 		(*ep->printsub)(data, cnt, buf, buflen);
942 	else
943 		encrypt_gen_printsub(data, cnt, buf, buflen);
944 }
945 #endif	/* ENCRYPTION */
946