xref: /openssh-portable/cipher.c (revision 540e8911)
1 /* $OpenBSD: cipher.c,v 1.100 2015/01/14 10:29:45 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  *
7  * As far as I am concerned, the code I have written for this software
8  * can be used freely for any purpose.  Any derived versions of this
9  * software must be clearly marked as such, and if the derived work is
10  * incompatible with the protocol description in the RFC file, it must be
11  * called by a name other than "ssh" or "Secure Shell".
12  *
13  *
14  * Copyright (c) 1999 Niels Provos.  All rights reserved.
15  * Copyright (c) 1999, 2000 Markus Friedl.  All rights reserved.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 #include "includes.h"
39 
40 #include <sys/types.h>
41 
42 #include <string.h>
43 #include <stdarg.h>
44 #include <stdio.h>
45 
46 #include "cipher.h"
47 #include "misc.h"
48 #include "sshbuf.h"
49 #include "ssherr.h"
50 #include "digest.h"
51 
52 #include "openbsd-compat/openssl-compat.h"
53 
54 #ifdef WITH_SSH1
55 extern const EVP_CIPHER *evp_ssh1_bf(void);
56 extern const EVP_CIPHER *evp_ssh1_3des(void);
57 extern int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
58 #endif
59 
60 struct sshcipher {
61 	char	*name;
62 	int	number;		/* for ssh1 only */
63 	u_int	block_size;
64 	u_int	key_len;
65 	u_int	iv_len;		/* defaults to block_size */
66 	u_int	auth_len;
67 	u_int	discard_len;
68 	u_int	flags;
69 #define CFLAG_CBC		(1<<0)
70 #define CFLAG_CHACHAPOLY	(1<<1)
71 #define CFLAG_AESCTR		(1<<2)
72 #define CFLAG_NONE		(1<<3)
73 #ifdef WITH_OPENSSL
74 	const EVP_CIPHER	*(*evptype)(void);
75 #else
76 	void	*ignored;
77 #endif
78 };
79 
80 static const struct sshcipher ciphers[] = {
81 #ifdef WITH_SSH1
82 	{ "des",	SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
83 	{ "3des",	SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
84 	{ "blowfish",	SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
85 #endif /* WITH_SSH1 */
86 #ifdef WITH_OPENSSL
87 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
88 	{ "3des-cbc",	SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
89 	{ "blowfish-cbc",
90 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
91 	{ "cast128-cbc",
92 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
93 	{ "arcfour",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
94 	{ "arcfour128",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
95 	{ "arcfour256",	SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
96 	{ "aes128-cbc",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
97 	{ "aes192-cbc",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
98 	{ "aes256-cbc",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
99 	{ "rijndael-cbc@lysator.liu.se",
100 			SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
101 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
102 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
103 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
104 # ifdef OPENSSL_HAVE_EVPGCM
105 	{ "aes128-gcm@openssh.com",
106 			SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
107 	{ "aes256-gcm@openssh.com",
108 			SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
109 # endif /* OPENSSL_HAVE_EVPGCM */
110 #else /* WITH_OPENSSL */
111 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, CFLAG_AESCTR, NULL },
112 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, CFLAG_AESCTR, NULL },
113 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, CFLAG_AESCTR, NULL },
114 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, CFLAG_NONE, NULL },
115 #endif /* WITH_OPENSSL */
116 	{ "chacha20-poly1305@openssh.com",
117 			SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
118 
119 	{ NULL,		SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
120 };
121 
122 /*--*/
123 
124 /* Returns a comma-separated list of supported ciphers. */
125 char *
126 cipher_alg_list(char sep, int auth_only)
127 {
128 	char *tmp, *ret = NULL;
129 	size_t nlen, rlen = 0;
130 	const struct sshcipher *c;
131 
132 	for (c = ciphers; c->name != NULL; c++) {
133 		if (c->number != SSH_CIPHER_SSH2)
134 			continue;
135 		if (auth_only && c->auth_len == 0)
136 			continue;
137 		if (ret != NULL)
138 			ret[rlen++] = sep;
139 		nlen = strlen(c->name);
140 		if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
141 			free(ret);
142 			return NULL;
143 		}
144 		ret = tmp;
145 		memcpy(ret + rlen, c->name, nlen + 1);
146 		rlen += nlen;
147 	}
148 	return ret;
149 }
150 
151 u_int
152 cipher_blocksize(const struct sshcipher *c)
153 {
154 	return (c->block_size);
155 }
156 
157 u_int
158 cipher_keylen(const struct sshcipher *c)
159 {
160 	return (c->key_len);
161 }
162 
163 u_int
164 cipher_seclen(const struct sshcipher *c)
165 {
166 	if (strcmp("3des-cbc", c->name) == 0)
167 		return 14;
168 	return cipher_keylen(c);
169 }
170 
171 u_int
172 cipher_authlen(const struct sshcipher *c)
173 {
174 	return (c->auth_len);
175 }
176 
177 u_int
178 cipher_ivlen(const struct sshcipher *c)
179 {
180 	/*
181 	 * Default is cipher block size, except for chacha20+poly1305 that
182 	 * needs no IV. XXX make iv_len == -1 default?
183 	 */
184 	return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
185 	    c->iv_len : c->block_size;
186 }
187 
188 u_int
189 cipher_get_number(const struct sshcipher *c)
190 {
191 	return (c->number);
192 }
193 
194 u_int
195 cipher_is_cbc(const struct sshcipher *c)
196 {
197 	return (c->flags & CFLAG_CBC) != 0;
198 }
199 
200 u_int
201 cipher_mask_ssh1(int client)
202 {
203 	u_int mask = 0;
204 	mask |= 1 << SSH_CIPHER_3DES;		/* Mandatory */
205 	mask |= 1 << SSH_CIPHER_BLOWFISH;
206 	if (client) {
207 		mask |= 1 << SSH_CIPHER_DES;
208 	}
209 	return mask;
210 }
211 
212 const struct sshcipher *
213 cipher_by_name(const char *name)
214 {
215 	const struct sshcipher *c;
216 	for (c = ciphers; c->name != NULL; c++)
217 		if (strcmp(c->name, name) == 0)
218 			return c;
219 	return NULL;
220 }
221 
222 const struct sshcipher *
223 cipher_by_number(int id)
224 {
225 	const struct sshcipher *c;
226 	for (c = ciphers; c->name != NULL; c++)
227 		if (c->number == id)
228 			return c;
229 	return NULL;
230 }
231 
232 #define	CIPHER_SEP	","
233 int
234 ciphers_valid(const char *names)
235 {
236 	const struct sshcipher *c;
237 	char *cipher_list, *cp;
238 	char *p;
239 
240 	if (names == NULL || strcmp(names, "") == 0)
241 		return 0;
242 	if ((cipher_list = cp = strdup(names)) == NULL)
243 		return 0;
244 	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
245 	    (p = strsep(&cp, CIPHER_SEP))) {
246 		c = cipher_by_name(p);
247 		if (c == NULL || c->number != SSH_CIPHER_SSH2) {
248 			free(cipher_list);
249 			return 0;
250 		}
251 	}
252 	free(cipher_list);
253 	return 1;
254 }
255 
256 /*
257  * Parses the name of the cipher.  Returns the number of the corresponding
258  * cipher, or -1 on error.
259  */
260 
261 int
262 cipher_number(const char *name)
263 {
264 	const struct sshcipher *c;
265 	if (name == NULL)
266 		return -1;
267 	for (c = ciphers; c->name != NULL; c++)
268 		if (strcasecmp(c->name, name) == 0)
269 			return c->number;
270 	return -1;
271 }
272 
273 char *
274 cipher_name(int id)
275 {
276 	const struct sshcipher *c = cipher_by_number(id);
277 	return (c==NULL) ? "<unknown>" : c->name;
278 }
279 
280 const char *
281 cipher_warning_message(const struct sshcipher_ctx *cc)
282 {
283 	if (cc == NULL || cc->cipher == NULL)
284 		return NULL;
285 	if (cc->cipher->number == SSH_CIPHER_DES)
286 		return "use of DES is strongly discouraged due to "
287 		    "cryptographic weaknesses";
288 	return NULL;
289 }
290 
291 int
292 cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
293     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
294     int do_encrypt)
295 {
296 #ifdef WITH_OPENSSL
297 	int ret = SSH_ERR_INTERNAL_ERROR;
298 	const EVP_CIPHER *type;
299 	int klen;
300 	u_char *junk, *discard;
301 
302 	if (cipher->number == SSH_CIPHER_DES) {
303 		if (keylen > 8)
304 			keylen = 8;
305 	}
306 #endif
307 	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
308 	cc->encrypt = do_encrypt;
309 
310 	if (keylen < cipher->key_len ||
311 	    (iv != NULL && ivlen < cipher_ivlen(cipher)))
312 		return SSH_ERR_INVALID_ARGUMENT;
313 
314 	cc->cipher = cipher;
315 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
316 		return chachapoly_init(&cc->cp_ctx, key, keylen);
317 	}
318 #ifndef WITH_OPENSSL
319 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
320 		aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
321 		aesctr_ivsetup(&cc->ac_ctx, iv);
322 		return 0;
323 	}
324 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
325 		return 0;
326 	return SSH_ERR_INVALID_ARGUMENT;
327 #else
328 	type = (*cipher->evptype)();
329 	EVP_CIPHER_CTX_init(&cc->evp);
330 	if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
331 	    (do_encrypt == CIPHER_ENCRYPT)) == 0) {
332 		ret = SSH_ERR_LIBCRYPTO_ERROR;
333 		goto bad;
334 	}
335 	if (cipher_authlen(cipher) &&
336 	    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
337 	    -1, (u_char *)iv)) {
338 		ret = SSH_ERR_LIBCRYPTO_ERROR;
339 		goto bad;
340 	}
341 	klen = EVP_CIPHER_CTX_key_length(&cc->evp);
342 	if (klen > 0 && keylen != (u_int)klen) {
343 		if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) {
344 			ret = SSH_ERR_LIBCRYPTO_ERROR;
345 			goto bad;
346 		}
347 	}
348 	if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
349 		ret = SSH_ERR_LIBCRYPTO_ERROR;
350 		goto bad;
351 	}
352 
353 	if (cipher->discard_len > 0) {
354 		if ((junk = malloc(cipher->discard_len)) == NULL ||
355 		    (discard = malloc(cipher->discard_len)) == NULL) {
356 			if (junk != NULL)
357 				free(junk);
358 			ret = SSH_ERR_ALLOC_FAIL;
359 			goto bad;
360 		}
361 		ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
362 		explicit_bzero(discard, cipher->discard_len);
363 		free(junk);
364 		free(discard);
365 		if (ret != 1) {
366 			ret = SSH_ERR_LIBCRYPTO_ERROR;
367  bad:
368 			EVP_CIPHER_CTX_cleanup(&cc->evp);
369 			return ret;
370 		}
371 	}
372 #endif
373 	return 0;
374 }
375 
376 /*
377  * cipher_crypt() operates as following:
378  * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
379  * Theses bytes are treated as additional authenticated data for
380  * authenticated encryption modes.
381  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
382  * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
383  * This tag is written on encryption and verified on decryption.
384  * Both 'aadlen' and 'authlen' can be set to 0.
385  */
386 int
387 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
388    const u_char *src, u_int len, u_int aadlen, u_int authlen)
389 {
390 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
391 		return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
392 		    len, aadlen, authlen, cc->encrypt);
393 	}
394 #ifndef WITH_OPENSSL
395 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
396 		if (aadlen)
397 			memcpy(dest, src, aadlen);
398 		aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
399 		    dest + aadlen, len);
400 		return 0;
401 	}
402 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
403 		memcpy(dest, src, aadlen + len);
404 		return 0;
405 	}
406 	return SSH_ERR_INVALID_ARGUMENT;
407 #else
408 	if (authlen) {
409 		u_char lastiv[1];
410 
411 		if (authlen != cipher_authlen(cc->cipher))
412 			return SSH_ERR_INVALID_ARGUMENT;
413 		/* increment IV */
414 		if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
415 		    1, lastiv))
416 			return SSH_ERR_LIBCRYPTO_ERROR;
417 		/* set tag on decyption */
418 		if (!cc->encrypt &&
419 		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
420 		    authlen, (u_char *)src + aadlen + len))
421 			return SSH_ERR_LIBCRYPTO_ERROR;
422 	}
423 	if (aadlen) {
424 		if (authlen &&
425 		    EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
426 			return SSH_ERR_LIBCRYPTO_ERROR;
427 		memcpy(dest, src, aadlen);
428 	}
429 	if (len % cc->cipher->block_size)
430 		return SSH_ERR_INVALID_ARGUMENT;
431 	if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
432 	    len) < 0)
433 		return SSH_ERR_LIBCRYPTO_ERROR;
434 	if (authlen) {
435 		/* compute tag (on encrypt) or verify tag (on decrypt) */
436 		if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
437 			return cc->encrypt ?
438 			    SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
439 		if (cc->encrypt &&
440 		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
441 		    authlen, dest + aadlen + len))
442 			return SSH_ERR_LIBCRYPTO_ERROR;
443 	}
444 	return 0;
445 #endif
446 }
447 
448 /* Extract the packet length, including any decryption necessary beforehand */
449 int
450 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
451     const u_char *cp, u_int len)
452 {
453 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
454 		return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
455 		    cp, len);
456 	if (len < 4)
457 		return SSH_ERR_MESSAGE_INCOMPLETE;
458 	*plenp = get_u32(cp);
459 	return 0;
460 }
461 
462 int
463 cipher_cleanup(struct sshcipher_ctx *cc)
464 {
465 	if (cc == NULL || cc->cipher == NULL)
466 		return 0;
467 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
468 		explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
469 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
470 		explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
471 #ifdef WITH_OPENSSL
472 	else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
473 		return SSH_ERR_LIBCRYPTO_ERROR;
474 #endif
475 	return 0;
476 }
477 
478 /*
479  * Selects the cipher, and keys if by computing the MD5 checksum of the
480  * passphrase and using the resulting 16 bytes as the key.
481  */
482 int
483 cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
484     const char *passphrase, int do_encrypt)
485 {
486 	u_char digest[16];
487 	int r = SSH_ERR_INTERNAL_ERROR;
488 
489 	if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
490 	    passphrase, strlen(passphrase),
491 	    digest, sizeof(digest))) != 0)
492 		goto out;
493 
494 	r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
495  out:
496 	explicit_bzero(digest, sizeof(digest));
497 	return r;
498 }
499 
500 /*
501  * Exports an IV from the sshcipher_ctx required to export the key
502  * state back from the unprivileged child to the privileged parent
503  * process.
504  */
505 int
506 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
507 {
508 	const struct sshcipher *c = cc->cipher;
509 	int ivlen = 0;
510 
511 	if (c->number == SSH_CIPHER_3DES)
512 		ivlen = 24;
513 	else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
514 		ivlen = 0;
515 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
516 		ivlen = sizeof(cc->ac_ctx.ctr);
517 #ifdef WITH_OPENSSL
518 	else
519 		ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
520 #endif /* WITH_OPENSSL */
521 	return (ivlen);
522 }
523 
524 int
525 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
526 {
527 	const struct sshcipher *c = cc->cipher;
528 #ifdef WITH_OPENSSL
529  	int evplen;
530 #endif
531 
532 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
533 		if (len != 0)
534 			return SSH_ERR_INVALID_ARGUMENT;
535 		return 0;
536 	}
537 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
538 		if (len != sizeof(cc->ac_ctx.ctr))
539 			return SSH_ERR_INVALID_ARGUMENT;
540 		memcpy(iv, cc->ac_ctx.ctr, len);
541 		return 0;
542 	}
543 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
544 		return 0;
545 
546 	switch (c->number) {
547 #ifdef WITH_OPENSSL
548 	case SSH_CIPHER_SSH2:
549 	case SSH_CIPHER_DES:
550 	case SSH_CIPHER_BLOWFISH:
551 		evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
552 		if (evplen == 0)
553 			return 0;
554 		else if (evplen < 0)
555 			return SSH_ERR_LIBCRYPTO_ERROR;
556 		if ((u_int)evplen != len)
557 			return SSH_ERR_INVALID_ARGUMENT;
558 #ifndef OPENSSL_HAVE_EVPCTR
559 		if (c->evptype == evp_aes_128_ctr)
560 			ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
561 		else
562 #endif
563 		if (cipher_authlen(c)) {
564 			if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
565 			   len, iv))
566 			       return SSH_ERR_LIBCRYPTO_ERROR;
567 		} else
568 			memcpy(iv, cc->evp.iv, len);
569 		break;
570 #endif
571 #ifdef WITH_SSH1
572 	case SSH_CIPHER_3DES:
573 		return ssh1_3des_iv(&cc->evp, 0, iv, 24);
574 #endif
575 	default:
576 		return SSH_ERR_INVALID_ARGUMENT;
577 	}
578 	return 0;
579 }
580 
581 int
582 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
583 {
584 	const struct sshcipher *c = cc->cipher;
585 #ifdef WITH_OPENSSL
586  	int evplen = 0;
587 #endif
588 
589 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
590 		return 0;
591 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
592 		return 0;
593 
594 	switch (c->number) {
595 #ifdef WITH_OPENSSL
596 	case SSH_CIPHER_SSH2:
597 	case SSH_CIPHER_DES:
598 	case SSH_CIPHER_BLOWFISH:
599 		evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
600 		if (evplen <= 0)
601 			return SSH_ERR_LIBCRYPTO_ERROR;
602 		if (cipher_authlen(c)) {
603 			/* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
604 			if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
605 			    EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
606 				return SSH_ERR_LIBCRYPTO_ERROR;
607 		} else
608 			memcpy(cc->evp.iv, iv, evplen);
609 		break;
610 #endif
611 #ifdef WITH_SSH1
612 	case SSH_CIPHER_3DES:
613 		return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
614 #endif
615 	default:
616 		return SSH_ERR_INVALID_ARGUMENT;
617 	}
618 	return 0;
619 }
620 
621 #ifdef WITH_OPENSSL
622 #define EVP_X_STATE(evp)	(evp).cipher_data
623 #define EVP_X_STATE_LEN(evp)	(evp).cipher->ctx_size
624 #endif
625 
626 int
627 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
628 {
629 #ifdef WITH_OPENSSL
630 	const struct sshcipher *c = cc->cipher;
631 	int plen = 0;
632 
633 	if (c->evptype == EVP_rc4) {
634 		plen = EVP_X_STATE_LEN(cc->evp);
635 		if (dat == NULL)
636 			return (plen);
637 		memcpy(dat, EVP_X_STATE(cc->evp), plen);
638 	}
639 	return (plen);
640 #else
641 	return 0;
642 #endif
643 }
644 
645 void
646 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
647 {
648 #ifdef WITH_OPENSSL
649 	const struct sshcipher *c = cc->cipher;
650 	int plen;
651 
652 	if (c->evptype == EVP_rc4) {
653 		plen = EVP_X_STATE_LEN(cc->evp);
654 		memcpy(EVP_X_STATE(cc->evp), dat, plen);
655 	}
656 #endif
657 }
658