xref: /openssh-portable/cipher.c (revision 4706c1d8)
1 /* $OpenBSD: cipher.c,v 1.102 2016/08/03 05:41:57 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_ctx {
61 	int	plaintext;
62 	int	encrypt;
63 	EVP_CIPHER_CTX *evp;
64 	struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
65 	struct aesctr_ctx ac_ctx; /* XXX union with evp? */
66 	const struct sshcipher *cipher;
67 };
68 
69 struct sshcipher {
70 	char	*name;
71 	int	number;		/* for ssh1 only */
72 	u_int	block_size;
73 	u_int	key_len;
74 	u_int	iv_len;		/* defaults to block_size */
75 	u_int	auth_len;
76 	u_int	discard_len;
77 	u_int	flags;
78 #define CFLAG_CBC		(1<<0)
79 #define CFLAG_CHACHAPOLY	(1<<1)
80 #define CFLAG_AESCTR		(1<<2)
81 #define CFLAG_NONE		(1<<3)
82 #ifdef WITH_OPENSSL
83 	const EVP_CIPHER	*(*evptype)(void);
84 #else
85 	void	*ignored;
86 #endif
87 };
88 
89 static const struct sshcipher ciphers[] = {
90 #ifdef WITH_SSH1
91 	{ "des",	SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
92 	{ "3des",	SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
93 # ifndef OPENSSL_NO_BF
94 	{ "blowfish",	SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
95 # endif /* OPENSSL_NO_BF */
96 #endif /* WITH_SSH1 */
97 #ifdef WITH_OPENSSL
98 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
99 	{ "3des-cbc",	SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
100 # ifndef OPENSSL_NO_BF
101 	{ "blowfish-cbc",
102 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
103 # endif /* OPENSSL_NO_BF */
104 # ifndef OPENSSL_NO_CAST
105 	{ "cast128-cbc",
106 			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
107 # endif /* OPENSSL_NO_CAST */
108 # ifndef OPENSSL_NO_RC4
109 	{ "arcfour",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
110 	{ "arcfour128",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
111 	{ "arcfour256",	SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
112 # endif /* OPENSSL_NO_RC4 */
113 	{ "aes128-cbc",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
114 	{ "aes192-cbc",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
115 	{ "aes256-cbc",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
116 	{ "rijndael-cbc@lysator.liu.se",
117 			SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
118 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
119 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
120 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
121 # ifdef OPENSSL_HAVE_EVPGCM
122 	{ "aes128-gcm@openssh.com",
123 			SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
124 	{ "aes256-gcm@openssh.com",
125 			SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
126 # endif /* OPENSSL_HAVE_EVPGCM */
127 #else /* WITH_OPENSSL */
128 	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, CFLAG_AESCTR, NULL },
129 	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, CFLAG_AESCTR, NULL },
130 	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, CFLAG_AESCTR, NULL },
131 	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, CFLAG_NONE, NULL },
132 #endif /* WITH_OPENSSL */
133 	{ "chacha20-poly1305@openssh.com",
134 			SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
135 
136 	{ NULL,		SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
137 };
138 
139 /*--*/
140 
141 /* Returns a comma-separated list of supported ciphers. */
142 char *
143 cipher_alg_list(char sep, int auth_only)
144 {
145 	char *tmp, *ret = NULL;
146 	size_t nlen, rlen = 0;
147 	const struct sshcipher *c;
148 
149 	for (c = ciphers; c->name != NULL; c++) {
150 		if (c->number != SSH_CIPHER_SSH2)
151 			continue;
152 		if (auth_only && c->auth_len == 0)
153 			continue;
154 		if (ret != NULL)
155 			ret[rlen++] = sep;
156 		nlen = strlen(c->name);
157 		if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
158 			free(ret);
159 			return NULL;
160 		}
161 		ret = tmp;
162 		memcpy(ret + rlen, c->name, nlen + 1);
163 		rlen += nlen;
164 	}
165 	return ret;
166 }
167 
168 u_int
169 cipher_blocksize(const struct sshcipher *c)
170 {
171 	return (c->block_size);
172 }
173 
174 u_int
175 cipher_keylen(const struct sshcipher *c)
176 {
177 	return (c->key_len);
178 }
179 
180 u_int
181 cipher_seclen(const struct sshcipher *c)
182 {
183 	if (strcmp("3des-cbc", c->name) == 0)
184 		return 14;
185 	return cipher_keylen(c);
186 }
187 
188 u_int
189 cipher_authlen(const struct sshcipher *c)
190 {
191 	return (c->auth_len);
192 }
193 
194 u_int
195 cipher_ivlen(const struct sshcipher *c)
196 {
197 	/*
198 	 * Default is cipher block size, except for chacha20+poly1305 that
199 	 * needs no IV. XXX make iv_len == -1 default?
200 	 */
201 	return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
202 	    c->iv_len : c->block_size;
203 }
204 
205 u_int
206 cipher_get_number(const struct sshcipher *c)
207 {
208 	return (c->number);
209 }
210 
211 u_int
212 cipher_is_cbc(const struct sshcipher *c)
213 {
214 	return (c->flags & CFLAG_CBC) != 0;
215 }
216 
217 u_int
218 cipher_ctx_is_plaintext(struct sshcipher_ctx *cc)
219 {
220 	return cc->plaintext;
221 }
222 
223 u_int
224 cipher_ctx_get_number(struct sshcipher_ctx *cc)
225 {
226 	return cc->cipher->number;
227 }
228 
229 u_int
230 cipher_mask_ssh1(int client)
231 {
232 	u_int mask = 0;
233 	mask |= 1 << SSH_CIPHER_3DES;		/* Mandatory */
234 	mask |= 1 << SSH_CIPHER_BLOWFISH;
235 	if (client) {
236 		mask |= 1 << SSH_CIPHER_DES;
237 	}
238 	return mask;
239 }
240 
241 const struct sshcipher *
242 cipher_by_name(const char *name)
243 {
244 	const struct sshcipher *c;
245 	for (c = ciphers; c->name != NULL; c++)
246 		if (strcmp(c->name, name) == 0)
247 			return c;
248 	return NULL;
249 }
250 
251 const struct sshcipher *
252 cipher_by_number(int id)
253 {
254 	const struct sshcipher *c;
255 	for (c = ciphers; c->name != NULL; c++)
256 		if (c->number == id)
257 			return c;
258 	return NULL;
259 }
260 
261 #define	CIPHER_SEP	","
262 int
263 ciphers_valid(const char *names)
264 {
265 	const struct sshcipher *c;
266 	char *cipher_list, *cp;
267 	char *p;
268 
269 	if (names == NULL || strcmp(names, "") == 0)
270 		return 0;
271 	if ((cipher_list = cp = strdup(names)) == NULL)
272 		return 0;
273 	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
274 	    (p = strsep(&cp, CIPHER_SEP))) {
275 		c = cipher_by_name(p);
276 		if (c == NULL || c->number != SSH_CIPHER_SSH2) {
277 			free(cipher_list);
278 			return 0;
279 		}
280 	}
281 	free(cipher_list);
282 	return 1;
283 }
284 
285 /*
286  * Parses the name of the cipher.  Returns the number of the corresponding
287  * cipher, or -1 on error.
288  */
289 
290 int
291 cipher_number(const char *name)
292 {
293 	const struct sshcipher *c;
294 	if (name == NULL)
295 		return -1;
296 	for (c = ciphers; c->name != NULL; c++)
297 		if (strcasecmp(c->name, name) == 0)
298 			return c->number;
299 	return -1;
300 }
301 
302 char *
303 cipher_name(int id)
304 {
305 	const struct sshcipher *c = cipher_by_number(id);
306 	return (c==NULL) ? "<unknown>" : c->name;
307 }
308 
309 const char *
310 cipher_warning_message(const struct sshcipher_ctx *cc)
311 {
312 	if (cc == NULL || cc->cipher == NULL)
313 		return NULL;
314 	if (cc->cipher->number == SSH_CIPHER_DES)
315 		return "use of DES is strongly discouraged due to "
316 		    "cryptographic weaknesses";
317 	return NULL;
318 }
319 
320 int
321 cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher,
322     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
323     int do_encrypt)
324 {
325 	struct sshcipher_ctx *cc = NULL;
326 	int ret = SSH_ERR_INTERNAL_ERROR;
327 #ifdef WITH_OPENSSL
328 	const EVP_CIPHER *type;
329 	int klen;
330 	u_char *junk, *discard;
331 #endif
332 
333 	*ccp = NULL;
334 	if ((cc = calloc(sizeof(*cc), 1)) == NULL)
335 		return SSH_ERR_ALLOC_FAIL;
336 
337 	if (cipher->number == SSH_CIPHER_DES) {
338 		if (keylen > 8)
339 			keylen = 8;
340 	}
341 
342 	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
343 	cc->encrypt = do_encrypt;
344 
345 	if (keylen < cipher->key_len ||
346 	    (iv != NULL && ivlen < cipher_ivlen(cipher))) {
347 		ret = SSH_ERR_INVALID_ARGUMENT;
348 		goto out;
349 	}
350 
351 	cc->cipher = cipher;
352 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
353 		ret = chachapoly_init(&cc->cp_ctx, key, keylen);
354 		goto out;
355 	}
356 #ifndef WITH_OPENSSL
357 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
358 		aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
359 		aesctr_ivsetup(&cc->ac_ctx, iv);
360 		ret = 0;
361 		goto out;
362 	}
363 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
364 		ret = 0;
365 		goto out;
366 	}
367 	ret = SSH_ERR_INVALID_ARGUMENT;
368 	goto out;
369 #else /* WITH_OPENSSL */
370 	type = (*cipher->evptype)();
371 	if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) {
372 		ret = SSH_ERR_ALLOC_FAIL;
373 		goto out;
374 	}
375 	if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv,
376 	    (do_encrypt == CIPHER_ENCRYPT)) == 0) {
377 		ret = SSH_ERR_LIBCRYPTO_ERROR;
378 		goto out;
379 	}
380 	if (cipher_authlen(cipher) &&
381 	    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
382 	    -1, (u_char *)iv)) {
383 		ret = SSH_ERR_LIBCRYPTO_ERROR;
384 		goto out;
385 	}
386 	klen = EVP_CIPHER_CTX_key_length(cc->evp);
387 	if (klen > 0 && keylen != (u_int)klen) {
388 		if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) {
389 			ret = SSH_ERR_LIBCRYPTO_ERROR;
390 			goto out;
391 		}
392 	}
393 	if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
394 		ret = SSH_ERR_LIBCRYPTO_ERROR;
395 		goto out;
396 	}
397 
398 	if (cipher->discard_len > 0) {
399 		if ((junk = malloc(cipher->discard_len)) == NULL ||
400 		    (discard = malloc(cipher->discard_len)) == NULL) {
401 			free(junk);
402 			ret = SSH_ERR_ALLOC_FAIL;
403 			goto out;
404 		}
405 		ret = EVP_Cipher(cc->evp, discard, junk, cipher->discard_len);
406 		explicit_bzero(discard, cipher->discard_len);
407 		free(junk);
408 		free(discard);
409 		if (ret != 1) {
410 			ret = SSH_ERR_LIBCRYPTO_ERROR;
411 			goto out;
412 		}
413 	}
414 	ret = 0;
415 #endif /* WITH_OPENSSL */
416  out:
417 	if (ret == 0) {
418 		/* success */
419 		*ccp = cc;
420 	} else {
421 		if (cc != NULL) {
422 #ifdef WITH_OPENSSL
423 			if (cc->evp != NULL)
424 				EVP_CIPHER_CTX_free(cc->evp);
425 #endif /* WITH_OPENSSL */
426 			explicit_bzero(cc, sizeof(*cc));
427 			free(cc);
428 		}
429 	}
430 	return ret;
431 }
432 
433 /*
434  * cipher_crypt() operates as following:
435  * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
436  * Theses bytes are treated as additional authenticated data for
437  * authenticated encryption modes.
438  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
439  * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
440  * This tag is written on encryption and verified on decryption.
441  * Both 'aadlen' and 'authlen' can be set to 0.
442  */
443 int
444 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
445    const u_char *src, u_int len, u_int aadlen, u_int authlen)
446 {
447 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
448 		return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
449 		    len, aadlen, authlen, cc->encrypt);
450 	}
451 #ifndef WITH_OPENSSL
452 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
453 		if (aadlen)
454 			memcpy(dest, src, aadlen);
455 		aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
456 		    dest + aadlen, len);
457 		return 0;
458 	}
459 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
460 		memcpy(dest, src, aadlen + len);
461 		return 0;
462 	}
463 	return SSH_ERR_INVALID_ARGUMENT;
464 #else
465 	if (authlen) {
466 		u_char lastiv[1];
467 
468 		if (authlen != cipher_authlen(cc->cipher))
469 			return SSH_ERR_INVALID_ARGUMENT;
470 		/* increment IV */
471 		if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
472 		    1, lastiv))
473 			return SSH_ERR_LIBCRYPTO_ERROR;
474 		/* set tag on decyption */
475 		if (!cc->encrypt &&
476 		    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG,
477 		    authlen, (u_char *)src + aadlen + len))
478 			return SSH_ERR_LIBCRYPTO_ERROR;
479 	}
480 	if (aadlen) {
481 		if (authlen &&
482 		    EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0)
483 			return SSH_ERR_LIBCRYPTO_ERROR;
484 		memcpy(dest, src, aadlen);
485 	}
486 	if (len % cc->cipher->block_size)
487 		return SSH_ERR_INVALID_ARGUMENT;
488 	if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen,
489 	    len) < 0)
490 		return SSH_ERR_LIBCRYPTO_ERROR;
491 	if (authlen) {
492 		/* compute tag (on encrypt) or verify tag (on decrypt) */
493 		if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0)
494 			return cc->encrypt ?
495 			    SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
496 		if (cc->encrypt &&
497 		    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG,
498 		    authlen, dest + aadlen + len))
499 			return SSH_ERR_LIBCRYPTO_ERROR;
500 	}
501 	return 0;
502 #endif
503 }
504 
505 /* Extract the packet length, including any decryption necessary beforehand */
506 int
507 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
508     const u_char *cp, u_int len)
509 {
510 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
511 		return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
512 		    cp, len);
513 	if (len < 4)
514 		return SSH_ERR_MESSAGE_INCOMPLETE;
515 	*plenp = get_u32(cp);
516 	return 0;
517 }
518 
519 void
520 cipher_free(struct sshcipher_ctx *cc)
521 {
522 	if (cc == NULL)
523 		return;
524 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
525 		explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
526 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
527 		explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
528 #ifdef WITH_OPENSSL
529 	if (cc->evp != NULL) {
530 		EVP_CIPHER_CTX_free(cc->evp);
531 		cc->evp = NULL;
532 	}
533 #endif
534 	explicit_bzero(cc, sizeof(*cc));
535 	free(cc);
536 }
537 
538 /*
539  * Selects the cipher, and keys if by computing the MD5 checksum of the
540  * passphrase and using the resulting 16 bytes as the key.
541  */
542 int
543 cipher_set_key_string(struct sshcipher_ctx **ccp,
544     const struct sshcipher *cipher, const char *passphrase, int do_encrypt)
545 {
546 	u_char digest[16];
547 	int r = SSH_ERR_INTERNAL_ERROR;
548 
549 	if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
550 	    passphrase, strlen(passphrase),
551 	    digest, sizeof(digest))) != 0)
552 		goto out;
553 
554 	r = cipher_init(ccp, cipher, digest, 16, NULL, 0, do_encrypt);
555  out:
556 	explicit_bzero(digest, sizeof(digest));
557 	return r;
558 }
559 
560 /*
561  * Exports an IV from the sshcipher_ctx required to export the key
562  * state back from the unprivileged child to the privileged parent
563  * process.
564  */
565 int
566 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
567 {
568 	const struct sshcipher *c = cc->cipher;
569 	int ivlen = 0;
570 
571 	if (c->number == SSH_CIPHER_3DES)
572 		ivlen = 24;
573 	else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
574 		ivlen = 0;
575 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
576 		ivlen = sizeof(cc->ac_ctx.ctr);
577 #ifdef WITH_OPENSSL
578 	else
579 		ivlen = EVP_CIPHER_CTX_iv_length(cc->evp);
580 #endif /* WITH_OPENSSL */
581 	return (ivlen);
582 }
583 
584 int
585 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
586 {
587 	const struct sshcipher *c = cc->cipher;
588 #ifdef WITH_OPENSSL
589  	int evplen;
590 #endif
591 
592 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
593 		if (len != 0)
594 			return SSH_ERR_INVALID_ARGUMENT;
595 		return 0;
596 	}
597 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
598 		if (len != sizeof(cc->ac_ctx.ctr))
599 			return SSH_ERR_INVALID_ARGUMENT;
600 		memcpy(iv, cc->ac_ctx.ctr, len);
601 		return 0;
602 	}
603 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
604 		return 0;
605 
606 	switch (c->number) {
607 #ifdef WITH_OPENSSL
608 	case SSH_CIPHER_SSH2:
609 	case SSH_CIPHER_DES:
610 	case SSH_CIPHER_BLOWFISH:
611 		evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
612 		if (evplen == 0)
613 			return 0;
614 		else if (evplen < 0)
615 			return SSH_ERR_LIBCRYPTO_ERROR;
616 		if ((u_int)evplen != len)
617 			return SSH_ERR_INVALID_ARGUMENT;
618 #ifndef OPENSSL_HAVE_EVPCTR
619 		if (c->evptype == evp_aes_128_ctr)
620 			ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
621 		else
622 #endif
623 		if (cipher_authlen(c)) {
624 			if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
625 			   len, iv))
626 			       return SSH_ERR_LIBCRYPTO_ERROR;
627 		} else
628 			memcpy(iv, cc->evp->iv, len);
629 		break;
630 #endif
631 #ifdef WITH_SSH1
632 	case SSH_CIPHER_3DES:
633 		return ssh1_3des_iv(cc->evp, 0, iv, 24);
634 #endif
635 	default:
636 		return SSH_ERR_INVALID_ARGUMENT;
637 	}
638 	return 0;
639 }
640 
641 int
642 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
643 {
644 	const struct sshcipher *c = cc->cipher;
645 #ifdef WITH_OPENSSL
646  	int evplen = 0;
647 #endif
648 
649 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
650 		return 0;
651 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
652 		return 0;
653 
654 	switch (c->number) {
655 #ifdef WITH_OPENSSL
656 	case SSH_CIPHER_SSH2:
657 	case SSH_CIPHER_DES:
658 	case SSH_CIPHER_BLOWFISH:
659 		evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
660 		if (evplen <= 0)
661 			return SSH_ERR_LIBCRYPTO_ERROR;
662 		if (cipher_authlen(c)) {
663 			/* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
664 			if (!EVP_CIPHER_CTX_ctrl(cc->evp,
665 			    EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
666 				return SSH_ERR_LIBCRYPTO_ERROR;
667 		} else
668 			memcpy(cc->evp->iv, iv, evplen);
669 		break;
670 #endif
671 #ifdef WITH_SSH1
672 	case SSH_CIPHER_3DES:
673 		return ssh1_3des_iv(cc->evp, 1, (u_char *)iv, 24);
674 #endif
675 	default:
676 		return SSH_ERR_INVALID_ARGUMENT;
677 	}
678 	return 0;
679 }
680 
681 #ifdef WITH_OPENSSL
682 #define EVP_X_STATE(evp)	(evp)->cipher_data
683 #define EVP_X_STATE_LEN(evp)	(evp)->cipher->ctx_size
684 #endif
685 
686 int
687 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
688 {
689 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
690 	const struct sshcipher *c = cc->cipher;
691 	int plen = 0;
692 
693 	if (c->evptype == EVP_rc4) {
694 		plen = EVP_X_STATE_LEN(cc->evp);
695 		if (dat == NULL)
696 			return (plen);
697 		memcpy(dat, EVP_X_STATE(cc->evp), plen);
698 	}
699 	return (plen);
700 #else
701 	return 0;
702 #endif
703 }
704 
705 void
706 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
707 {
708 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
709 	const struct sshcipher *c = cc->cipher;
710 	int plen;
711 
712 	if (c->evptype == EVP_rc4) {
713 		plen = EVP_X_STATE_LEN(cc->evp);
714 		memcpy(EVP_X_STATE(cc->evp), dat, plen);
715 	}
716 #endif
717 }
718