xref: /freebsd/crypto/openssh/cipher.c (revision 076ad2f836d5f49dc1375f1677335a48fe0d4b82)
1 /* $OpenBSD: cipher.c,v 1.101 2015/12/10 17:08:40 mmcc 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 # ifndef OPENSSL_NO_BF
85 	{ "blowfish",	SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
86 # endif /* OPENSSL_NO_BF */
87 #endif /* WITH_SSH1 */
88 #ifdef WITH_OPENSSL
89 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
90 	{ "3des-cbc",	SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
91 # ifndef OPENSSL_NO_BF
92 	{ "blowfish-cbc",
93 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
94 # endif /* OPENSSL_NO_BF */
95 # ifndef OPENSSL_NO_CAST
96 	{ "cast128-cbc",
97 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
98 # endif /* OPENSSL_NO_CAST */
99 # ifndef OPENSSL_NO_RC4
100 	{ "arcfour",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
101 	{ "arcfour128",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
102 	{ "arcfour256",	SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
103 # endif /* OPENSSL_NO_RC4 */
104 	{ "aes128-cbc",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
105 	{ "aes192-cbc",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
106 	{ "aes256-cbc",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
107 	{ "rijndael-cbc@lysator.liu.se",
108 			SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
109 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
110 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
111 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
112 # ifdef OPENSSL_HAVE_EVPGCM
113 	{ "aes128-gcm@openssh.com",
114 			SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
115 	{ "aes256-gcm@openssh.com",
116 			SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
117 # endif /* OPENSSL_HAVE_EVPGCM */
118 #else /* WITH_OPENSSL */
119 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, CFLAG_AESCTR, NULL },
120 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, CFLAG_AESCTR, NULL },
121 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, CFLAG_AESCTR, NULL },
122 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, CFLAG_NONE, NULL },
123 #endif /* WITH_OPENSSL */
124 	{ "chacha20-poly1305@openssh.com",
125 			SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
126 
127 	{ NULL,		SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
128 };
129 
130 /*--*/
131 
132 /* Returns a comma-separated list of supported ciphers. */
133 char *
134 cipher_alg_list(char sep, int auth_only)
135 {
136 	char *tmp, *ret = NULL;
137 	size_t nlen, rlen = 0;
138 	const struct sshcipher *c;
139 
140 	for (c = ciphers; c->name != NULL; c++) {
141 		if (c->number != SSH_CIPHER_SSH2)
142 			continue;
143 		if (auth_only && c->auth_len == 0)
144 			continue;
145 		if (ret != NULL)
146 			ret[rlen++] = sep;
147 		nlen = strlen(c->name);
148 		if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
149 			free(ret);
150 			return NULL;
151 		}
152 		ret = tmp;
153 		memcpy(ret + rlen, c->name, nlen + 1);
154 		rlen += nlen;
155 	}
156 	return ret;
157 }
158 
159 u_int
160 cipher_blocksize(const struct sshcipher *c)
161 {
162 	return (c->block_size);
163 }
164 
165 u_int
166 cipher_keylen(const struct sshcipher *c)
167 {
168 	return (c->key_len);
169 }
170 
171 u_int
172 cipher_seclen(const struct sshcipher *c)
173 {
174 	if (strcmp("3des-cbc", c->name) == 0)
175 		return 14;
176 	return cipher_keylen(c);
177 }
178 
179 u_int
180 cipher_authlen(const struct sshcipher *c)
181 {
182 	return (c->auth_len);
183 }
184 
185 u_int
186 cipher_ivlen(const struct sshcipher *c)
187 {
188 	/*
189 	 * Default is cipher block size, except for chacha20+poly1305 that
190 	 * needs no IV. XXX make iv_len == -1 default?
191 	 */
192 	return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
193 	    c->iv_len : c->block_size;
194 }
195 
196 u_int
197 cipher_get_number(const struct sshcipher *c)
198 {
199 	return (c->number);
200 }
201 
202 u_int
203 cipher_is_cbc(const struct sshcipher *c)
204 {
205 	return (c->flags & CFLAG_CBC) != 0;
206 }
207 
208 u_int
209 cipher_mask_ssh1(int client)
210 {
211 	u_int mask = 0;
212 	mask |= 1 << SSH_CIPHER_3DES;		/* Mandatory */
213 	mask |= 1 << SSH_CIPHER_BLOWFISH;
214 	if (client) {
215 		mask |= 1 << SSH_CIPHER_DES;
216 	}
217 	return mask;
218 }
219 
220 const struct sshcipher *
221 cipher_by_name(const char *name)
222 {
223 	const struct sshcipher *c;
224 	for (c = ciphers; c->name != NULL; c++)
225 		if (strcmp(c->name, name) == 0)
226 			return c;
227 	return NULL;
228 }
229 
230 const struct sshcipher *
231 cipher_by_number(int id)
232 {
233 	const struct sshcipher *c;
234 	for (c = ciphers; c->name != NULL; c++)
235 		if (c->number == id)
236 			return c;
237 	return NULL;
238 }
239 
240 #define	CIPHER_SEP	","
241 int
242 ciphers_valid(const char *names)
243 {
244 	const struct sshcipher *c;
245 	char *cipher_list, *cp;
246 	char *p;
247 
248 	if (names == NULL || strcmp(names, "") == 0)
249 		return 0;
250 	if ((cipher_list = cp = strdup(names)) == NULL)
251 		return 0;
252 	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
253 	    (p = strsep(&cp, CIPHER_SEP))) {
254 		c = cipher_by_name(p);
255 		if (c == NULL || c->number != SSH_CIPHER_SSH2) {
256 			free(cipher_list);
257 			return 0;
258 		}
259 	}
260 	free(cipher_list);
261 	return 1;
262 }
263 
264 /*
265  * Parses the name of the cipher.  Returns the number of the corresponding
266  * cipher, or -1 on error.
267  */
268 
269 int
270 cipher_number(const char *name)
271 {
272 	const struct sshcipher *c;
273 	if (name == NULL)
274 		return -1;
275 	for (c = ciphers; c->name != NULL; c++)
276 		if (strcasecmp(c->name, name) == 0)
277 			return c->number;
278 	return -1;
279 }
280 
281 char *
282 cipher_name(int id)
283 {
284 	const struct sshcipher *c = cipher_by_number(id);
285 	return (c==NULL) ? "<unknown>" : c->name;
286 }
287 
288 const char *
289 cipher_warning_message(const struct sshcipher_ctx *cc)
290 {
291 	if (cc == NULL || cc->cipher == NULL)
292 		return NULL;
293 	if (cc->cipher->number == SSH_CIPHER_DES)
294 		return "use of DES is strongly discouraged due to "
295 		    "cryptographic weaknesses";
296 	return NULL;
297 }
298 
299 int
300 cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
301     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
302     int do_encrypt)
303 {
304 #ifdef WITH_OPENSSL
305 	int ret = SSH_ERR_INTERNAL_ERROR;
306 	const EVP_CIPHER *type;
307 	int klen;
308 	u_char *junk, *discard;
309 
310 	if (cipher->number == SSH_CIPHER_DES) {
311 		if (keylen > 8)
312 			keylen = 8;
313 	}
314 #endif
315 	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
316 	cc->encrypt = do_encrypt;
317 
318 	if (keylen < cipher->key_len ||
319 	    (iv != NULL && ivlen < cipher_ivlen(cipher)))
320 		return SSH_ERR_INVALID_ARGUMENT;
321 
322 	cc->cipher = cipher;
323 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
324 		return chachapoly_init(&cc->cp_ctx, key, keylen);
325 	}
326 #ifndef WITH_OPENSSL
327 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
328 		aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
329 		aesctr_ivsetup(&cc->ac_ctx, iv);
330 		return 0;
331 	}
332 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
333 		return 0;
334 	return SSH_ERR_INVALID_ARGUMENT;
335 #else
336 	type = (*cipher->evptype)();
337 	EVP_CIPHER_CTX_init(&cc->evp);
338 	if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
339 	    (do_encrypt == CIPHER_ENCRYPT)) == 0) {
340 		ret = SSH_ERR_LIBCRYPTO_ERROR;
341 		goto bad;
342 	}
343 	if (cipher_authlen(cipher) &&
344 	    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
345 	    -1, (u_char *)iv)) {
346 		ret = SSH_ERR_LIBCRYPTO_ERROR;
347 		goto bad;
348 	}
349 	klen = EVP_CIPHER_CTX_key_length(&cc->evp);
350 	if (klen > 0 && keylen != (u_int)klen) {
351 		if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) {
352 			ret = SSH_ERR_LIBCRYPTO_ERROR;
353 			goto bad;
354 		}
355 	}
356 	if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
357 		ret = SSH_ERR_LIBCRYPTO_ERROR;
358 		goto bad;
359 	}
360 
361 	if (cipher->discard_len > 0) {
362 		if ((junk = malloc(cipher->discard_len)) == NULL ||
363 		    (discard = malloc(cipher->discard_len)) == NULL) {
364 			free(junk);
365 			ret = SSH_ERR_ALLOC_FAIL;
366 			goto bad;
367 		}
368 		ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
369 		explicit_bzero(discard, cipher->discard_len);
370 		free(junk);
371 		free(discard);
372 		if (ret != 1) {
373 			ret = SSH_ERR_LIBCRYPTO_ERROR;
374  bad:
375 			EVP_CIPHER_CTX_cleanup(&cc->evp);
376 			return ret;
377 		}
378 	}
379 #endif
380 	return 0;
381 }
382 
383 /*
384  * cipher_crypt() operates as following:
385  * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
386  * Theses bytes are treated as additional authenticated data for
387  * authenticated encryption modes.
388  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
389  * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
390  * This tag is written on encryption and verified on decryption.
391  * Both 'aadlen' and 'authlen' can be set to 0.
392  */
393 int
394 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
395    const u_char *src, u_int len, u_int aadlen, u_int authlen)
396 {
397 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
398 		return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
399 		    len, aadlen, authlen, cc->encrypt);
400 	}
401 #ifndef WITH_OPENSSL
402 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
403 		if (aadlen)
404 			memcpy(dest, src, aadlen);
405 		aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
406 		    dest + aadlen, len);
407 		return 0;
408 	}
409 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
410 		memcpy(dest, src, aadlen + len);
411 		return 0;
412 	}
413 	return SSH_ERR_INVALID_ARGUMENT;
414 #else
415 	if (authlen) {
416 		u_char lastiv[1];
417 
418 		if (authlen != cipher_authlen(cc->cipher))
419 			return SSH_ERR_INVALID_ARGUMENT;
420 		/* increment IV */
421 		if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
422 		    1, lastiv))
423 			return SSH_ERR_LIBCRYPTO_ERROR;
424 		/* set tag on decyption */
425 		if (!cc->encrypt &&
426 		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
427 		    authlen, (u_char *)src + aadlen + len))
428 			return SSH_ERR_LIBCRYPTO_ERROR;
429 	}
430 	if (aadlen) {
431 		if (authlen &&
432 		    EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
433 			return SSH_ERR_LIBCRYPTO_ERROR;
434 		memcpy(dest, src, aadlen);
435 	}
436 	if (len % cc->cipher->block_size)
437 		return SSH_ERR_INVALID_ARGUMENT;
438 	if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
439 	    len) < 0)
440 		return SSH_ERR_LIBCRYPTO_ERROR;
441 	if (authlen) {
442 		/* compute tag (on encrypt) or verify tag (on decrypt) */
443 		if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
444 			return cc->encrypt ?
445 			    SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
446 		if (cc->encrypt &&
447 		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
448 		    authlen, dest + aadlen + len))
449 			return SSH_ERR_LIBCRYPTO_ERROR;
450 	}
451 	return 0;
452 #endif
453 }
454 
455 /* Extract the packet length, including any decryption necessary beforehand */
456 int
457 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
458     const u_char *cp, u_int len)
459 {
460 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
461 		return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
462 		    cp, len);
463 	if (len < 4)
464 		return SSH_ERR_MESSAGE_INCOMPLETE;
465 	*plenp = get_u32(cp);
466 	return 0;
467 }
468 
469 int
470 cipher_cleanup(struct sshcipher_ctx *cc)
471 {
472 	if (cc == NULL || cc->cipher == NULL)
473 		return 0;
474 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
475 		explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
476 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
477 		explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
478 #ifdef WITH_OPENSSL
479 	else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
480 		return SSH_ERR_LIBCRYPTO_ERROR;
481 #endif
482 	return 0;
483 }
484 
485 /*
486  * Selects the cipher, and keys if by computing the MD5 checksum of the
487  * passphrase and using the resulting 16 bytes as the key.
488  */
489 int
490 cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
491     const char *passphrase, int do_encrypt)
492 {
493 	u_char digest[16];
494 	int r = SSH_ERR_INTERNAL_ERROR;
495 
496 	if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
497 	    passphrase, strlen(passphrase),
498 	    digest, sizeof(digest))) != 0)
499 		goto out;
500 
501 	r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
502  out:
503 	explicit_bzero(digest, sizeof(digest));
504 	return r;
505 }
506 
507 /*
508  * Exports an IV from the sshcipher_ctx required to export the key
509  * state back from the unprivileged child to the privileged parent
510  * process.
511  */
512 int
513 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
514 {
515 	const struct sshcipher *c = cc->cipher;
516 	int ivlen = 0;
517 
518 	if (c->number == SSH_CIPHER_3DES)
519 		ivlen = 24;
520 	else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
521 		ivlen = 0;
522 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
523 		ivlen = sizeof(cc->ac_ctx.ctr);
524 #ifdef WITH_OPENSSL
525 	else
526 		ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
527 #endif /* WITH_OPENSSL */
528 	return (ivlen);
529 }
530 
531 int
532 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
533 {
534 	const struct sshcipher *c = cc->cipher;
535 #ifdef WITH_OPENSSL
536  	int evplen;
537 #endif
538 
539 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
540 		if (len != 0)
541 			return SSH_ERR_INVALID_ARGUMENT;
542 		return 0;
543 	}
544 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
545 		if (len != sizeof(cc->ac_ctx.ctr))
546 			return SSH_ERR_INVALID_ARGUMENT;
547 		memcpy(iv, cc->ac_ctx.ctr, len);
548 		return 0;
549 	}
550 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
551 		return 0;
552 
553 	switch (c->number) {
554 #ifdef WITH_OPENSSL
555 	case SSH_CIPHER_SSH2:
556 	case SSH_CIPHER_DES:
557 	case SSH_CIPHER_BLOWFISH:
558 		evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
559 		if (evplen == 0)
560 			return 0;
561 		else if (evplen < 0)
562 			return SSH_ERR_LIBCRYPTO_ERROR;
563 		if ((u_int)evplen != len)
564 			return SSH_ERR_INVALID_ARGUMENT;
565 #ifndef OPENSSL_HAVE_EVPCTR
566 		if (c->evptype == evp_aes_128_ctr)
567 			ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
568 		else
569 #endif
570 		if (cipher_authlen(c)) {
571 			if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
572 			   len, iv))
573 			       return SSH_ERR_LIBCRYPTO_ERROR;
574 		} else
575 			memcpy(iv, cc->evp.iv, len);
576 		break;
577 #endif
578 #ifdef WITH_SSH1
579 	case SSH_CIPHER_3DES:
580 		return ssh1_3des_iv(&cc->evp, 0, iv, 24);
581 #endif
582 	default:
583 		return SSH_ERR_INVALID_ARGUMENT;
584 	}
585 	return 0;
586 }
587 
588 int
589 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
590 {
591 	const struct sshcipher *c = cc->cipher;
592 #ifdef WITH_OPENSSL
593  	int evplen = 0;
594 #endif
595 
596 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
597 		return 0;
598 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
599 		return 0;
600 
601 	switch (c->number) {
602 #ifdef WITH_OPENSSL
603 	case SSH_CIPHER_SSH2:
604 	case SSH_CIPHER_DES:
605 	case SSH_CIPHER_BLOWFISH:
606 		evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
607 		if (evplen <= 0)
608 			return SSH_ERR_LIBCRYPTO_ERROR;
609 		if (cipher_authlen(c)) {
610 			/* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
611 			if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
612 			    EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
613 				return SSH_ERR_LIBCRYPTO_ERROR;
614 		} else
615 			memcpy(cc->evp.iv, iv, evplen);
616 		break;
617 #endif
618 #ifdef WITH_SSH1
619 	case SSH_CIPHER_3DES:
620 		return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
621 #endif
622 	default:
623 		return SSH_ERR_INVALID_ARGUMENT;
624 	}
625 	return 0;
626 }
627 
628 #ifdef WITH_OPENSSL
629 #define EVP_X_STATE(evp)	(evp).cipher_data
630 #define EVP_X_STATE_LEN(evp)	(evp).cipher->ctx_size
631 #endif
632 
633 int
634 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
635 {
636 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
637 	const struct sshcipher *c = cc->cipher;
638 	int plen = 0;
639 
640 	if (c->evptype == EVP_rc4) {
641 		plen = EVP_X_STATE_LEN(cc->evp);
642 		if (dat == NULL)
643 			return (plen);
644 		memcpy(dat, EVP_X_STATE(cc->evp), plen);
645 	}
646 	return (plen);
647 #else
648 	return 0;
649 #endif
650 }
651 
652 void
653 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
654 {
655 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
656 	const struct sshcipher *c = cc->cipher;
657 	int plen;
658 
659 	if (c->evptype == EVP_rc4) {
660 		plen = EVP_X_STATE_LEN(cc->evp);
661 		memcpy(EVP_X_STATE(cc->evp), dat, plen);
662 	}
663 #endif
664 }
665