1 /* $OpenBSD: cipher.c,v 1.99 2014/06/24 01:13:21 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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".
14 * Copyright (c) 1999 Niels Provos. All rights reserved.
15 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
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.
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.
40 #include <sys/types.h>
52 #include "openbsd-compat/openssl-compat.h"
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);
62 int number
; /* for ssh1 only */
65 u_int iv_len
; /* defaults to block_size */
69 #define CFLAG_CBC (1<<0)
70 #define CFLAG_CHACHAPOLY (1<<1)
71 #define CFLAG_AESCTR (1<<2)
72 #define CFLAG_NONE (1<<3)
74 const EVP_CIPHER
*(*evptype
)(void);
80 static const struct sshcipher ciphers
[] = {
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 */
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
},
90 SSH_CIPHER_SSH2
, 8, 16, 0, 0, 0, 1, EVP_bf_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
},
119 { NULL
, SSH_CIPHER_INVALID
, 0, 0, 0, 0, 0, 0, NULL
}
124 /* Returns a comma-separated list of supported ciphers. */
126 cipher_alg_list(char sep
, int auth_only
)
128 char *tmp
, *ret
= NULL
;
129 size_t nlen
, rlen
= 0;
130 const struct sshcipher
*c
;
132 for (c
= ciphers
; c
->name
!= NULL
; c
++) {
133 if (c
->number
!= SSH_CIPHER_SSH2
)
135 if (auth_only
&& c
->auth_len
== 0)
139 nlen
= strlen(c
->name
);
140 if ((tmp
= realloc(ret
, rlen
+ nlen
+ 2)) == NULL
) {
145 memcpy(ret
+ rlen
, c
->name
, nlen
+ 1);
152 cipher_blocksize(const struct sshcipher
*c
)
154 return (c
->block_size
);
158 cipher_keylen(const struct sshcipher
*c
)
164 cipher_seclen(const struct sshcipher
*c
)
166 if (strcmp("3des-cbc", c
->name
) == 0)
168 return cipher_keylen(c
);
172 cipher_authlen(const struct sshcipher
*c
)
174 return (c
->auth_len
);
178 cipher_ivlen(const struct sshcipher
*c
)
181 * Default is cipher block size, except for chacha20+poly1305 that
182 * needs no IV. XXX make iv_len == -1 default?
184 return (c
->iv_len
!= 0 || (c
->flags
& CFLAG_CHACHAPOLY
) != 0) ?
185 c
->iv_len
: c
->block_size
;
189 cipher_get_number(const struct sshcipher
*c
)
195 cipher_is_cbc(const struct sshcipher
*c
)
197 return (c
->flags
& CFLAG_CBC
) != 0;
201 cipher_mask_ssh1(int client
)
204 mask
|= 1 << SSH_CIPHER_3DES
; /* Mandatory */
205 mask
|= 1 << SSH_CIPHER_BLOWFISH
;
207 mask
|= 1 << SSH_CIPHER_DES
;
212 const struct sshcipher
*
213 cipher_by_name(const char *name
)
215 const struct sshcipher
*c
;
216 for (c
= ciphers
; c
->name
!= NULL
; c
++)
217 if (strcmp(c
->name
, name
) == 0)
222 const struct sshcipher
*
223 cipher_by_number(int id
)
225 const struct sshcipher
*c
;
226 for (c
= ciphers
; c
->name
!= NULL
; c
++)
232 #define CIPHER_SEP ","
234 ciphers_valid(const char *names
)
236 const struct sshcipher
*c
;
237 char *cipher_list
, *cp
;
240 if (names
== NULL
|| strcmp(names
, "") == 0)
242 if ((cipher_list
= cp
= strdup(names
)) == NULL
)
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
) {
257 * Parses the name of the cipher. Returns the number of the corresponding
258 * cipher, or -1 on error.
262 cipher_number(const char *name
)
264 const struct sshcipher
*c
;
267 for (c
= ciphers
; c
->name
!= NULL
; c
++)
268 if (strcasecmp(c
->name
, name
) == 0)
276 const struct sshcipher
*c
= cipher_by_number(id
);
277 return (c
==NULL
) ? "<unknown>" : c
->name
;
281 cipher_warning_message(const struct sshcipher_ctx
*cc
)
283 if (cc
== NULL
|| cc
->cipher
== NULL
)
285 if (cc
->cipher
->number
== SSH_CIPHER_DES
)
286 return "use of DES is strongly discouraged due to "
287 "cryptographic weaknesses";
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
,
297 int ret
= SSH_ERR_INTERNAL_ERROR
;
298 const EVP_CIPHER
*type
;
300 u_char
*junk
, *discard
;
302 if (cipher
->number
== SSH_CIPHER_DES
) {
307 cc
->plaintext
= (cipher
->number
== SSH_CIPHER_NONE
);
308 cc
->encrypt
= do_encrypt
;
310 if (keylen
< cipher
->key_len
||
311 (iv
!= NULL
&& ivlen
< cipher_ivlen(cipher
)))
312 return SSH_ERR_INVALID_ARGUMENT
;
315 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
316 return chachapoly_init(&cc
->cp_ctx
, key
, keylen
);
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
);
324 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
326 return SSH_ERR_INVALID_ARGUMENT
;
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
;
335 if (cipher_authlen(cipher
) &&
336 !EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_SET_IV_FIXED
,
338 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
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
;
348 if (EVP_CipherInit(&cc
->evp
, NULL
, (u_char
*)key
, NULL
, -1) == 0) {
349 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
353 if (cipher
->discard_len
> 0) {
354 if ((junk
= malloc(cipher
->discard_len
)) == NULL
||
355 (discard
= malloc(cipher
->discard_len
)) == NULL
) {
358 ret
= SSH_ERR_ALLOC_FAIL
;
361 ret
= EVP_Cipher(&cc
->evp
, discard
, junk
, cipher
->discard_len
);
362 explicit_bzero(discard
, cipher
->discard_len
);
366 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
368 EVP_CIPHER_CTX_cleanup(&cc
->evp
);
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.
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
)
390 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
391 return chachapoly_crypt(&cc
->cp_ctx
, seqnr
, dest
, src
,
392 len
, aadlen
, authlen
, cc
->encrypt
);
395 if ((cc
->cipher
->flags
& CFLAG_AESCTR
) != 0) {
397 memcpy(dest
, src
, aadlen
);
398 aesctr_encrypt_bytes(&cc
->ac_ctx
, src
+ aadlen
,
402 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0) {
403 memcpy(dest
, src
, aadlen
+ len
);
406 return SSH_ERR_INVALID_ARGUMENT
;
411 if (authlen
!= cipher_authlen(cc
->cipher
))
412 return SSH_ERR_INVALID_ARGUMENT
;
414 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_IV_GEN
,
416 return SSH_ERR_LIBCRYPTO_ERROR
;
417 /* set tag on decyption */
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
;
425 EVP_Cipher(&cc
->evp
, NULL
, (u_char
*)src
, aadlen
) < 0)
426 return SSH_ERR_LIBCRYPTO_ERROR
;
427 memcpy(dest
, src
, aadlen
);
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
,
433 return SSH_ERR_LIBCRYPTO_ERROR
;
435 /* compute tag (on encrypt) or verify tag (on decrypt) */
436 if (EVP_Cipher(&cc
->evp
, NULL
, NULL
, 0) < 0)
438 SSH_ERR_LIBCRYPTO_ERROR
: SSH_ERR_MAC_INVALID
;
440 !EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_GET_TAG
,
441 authlen
, dest
+ aadlen
+ len
))
442 return SSH_ERR_LIBCRYPTO_ERROR
;
448 /* Extract the packet length, including any decryption necessary beforehand */
450 cipher_get_length(struct sshcipher_ctx
*cc
, u_int
*plenp
, u_int seqnr
,
451 const u_char
*cp
, u_int len
)
453 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
454 return chachapoly_get_length(&cc
->cp_ctx
, plenp
, seqnr
,
457 return SSH_ERR_MESSAGE_INCOMPLETE
;
458 *plenp
= get_u32(cp
);
463 cipher_cleanup(struct sshcipher_ctx
*cc
)
465 if (cc
== NULL
|| cc
->cipher
== NULL
)
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
));
472 else if (EVP_CIPHER_CTX_cleanup(&cc
->evp
) == 0)
473 return SSH_ERR_LIBCRYPTO_ERROR
;
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.
483 cipher_set_key_string(struct sshcipher_ctx
*cc
, const struct sshcipher
*cipher
,
484 const char *passphrase
, int do_encrypt
)
487 int r
= SSH_ERR_INTERNAL_ERROR
;
489 if ((r
= ssh_digest_memory(SSH_DIGEST_MD5
,
490 passphrase
, strlen(passphrase
),
491 digest
, sizeof(digest
))) != 0)
494 r
= cipher_init(cc
, cipher
, digest
, 16, NULL
, 0, do_encrypt
);
496 explicit_bzero(digest
, sizeof(digest
));
501 * Exports an IV from the sshcipher_ctx required to export the key
502 * state back from the unprivileged child to the privileged parent
506 cipher_get_keyiv_len(const struct sshcipher_ctx
*cc
)
508 const struct sshcipher
*c
= cc
->cipher
;
511 if (c
->number
== SSH_CIPHER_3DES
)
513 else if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
517 ivlen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
518 #endif /* WITH_OPENSSL */
523 cipher_get_keyiv(struct sshcipher_ctx
*cc
, u_char
*iv
, u_int len
)
525 const struct sshcipher
*c
= cc
->cipher
;
530 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
532 return SSH_ERR_INVALID_ARGUMENT
;
535 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
540 case SSH_CIPHER_SSH2
:
542 case SSH_CIPHER_BLOWFISH
:
543 evplen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
547 return SSH_ERR_LIBCRYPTO_ERROR
;
548 if ((u_int
)evplen
!= len
)
549 return SSH_ERR_INVALID_ARGUMENT
;
550 #ifndef OPENSSL_HAVE_EVPCTR
551 if (c
->evptype
== evp_aes_128_ctr
)
552 ssh_aes_ctr_iv(&cc
->evp
, 0, iv
, len
);
555 if (cipher_authlen(c
)) {
556 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_IV_GEN
,
558 return SSH_ERR_LIBCRYPTO_ERROR
;
560 memcpy(iv
, cc
->evp
.iv
, len
);
564 case SSH_CIPHER_3DES
:
565 return ssh1_3des_iv(&cc
->evp
, 0, iv
, 24);
568 return SSH_ERR_INVALID_ARGUMENT
;
574 cipher_set_keyiv(struct sshcipher_ctx
*cc
, const u_char
*iv
)
576 const struct sshcipher
*c
= cc
->cipher
;
581 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
583 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
588 case SSH_CIPHER_SSH2
:
590 case SSH_CIPHER_BLOWFISH
:
591 evplen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
593 return SSH_ERR_LIBCRYPTO_ERROR
;
594 if (cipher_authlen(c
)) {
595 /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
596 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
,
597 EVP_CTRL_GCM_SET_IV_FIXED
, -1, (void *)iv
))
598 return SSH_ERR_LIBCRYPTO_ERROR
;
600 memcpy(cc
->evp
.iv
, iv
, evplen
);
604 case SSH_CIPHER_3DES
:
605 return ssh1_3des_iv(&cc
->evp
, 1, (u_char
*)iv
, 24);
608 return SSH_ERR_INVALID_ARGUMENT
;
614 #define EVP_X_STATE(evp) (evp).cipher_data
615 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
619 cipher_get_keycontext(const struct sshcipher_ctx
*cc
, u_char
*dat
)
622 const struct sshcipher
*c
= cc
->cipher
;
625 if (c
->evptype
== EVP_rc4
) {
626 plen
= EVP_X_STATE_LEN(cc
->evp
);
629 memcpy(dat
, EVP_X_STATE(cc
->evp
), plen
);
638 cipher_set_keycontext(struct sshcipher_ctx
*cc
, const u_char
*dat
)
641 const struct sshcipher
*c
= cc
->cipher
;
644 if (c
->evptype
== EVP_rc4
) {
645 plen
= EVP_X_STATE_LEN(cc
->evp
);
646 memcpy(EVP_X_STATE(cc
->evp
), dat
, plen
);