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);
60 /* for multi-threaded aes-ctr cipher */
61 extern const EVP_CIPHER
*evp_aes_ctr_mt(void);
63 /* no longer needed. replaced by evp pointer swap */
64 /* extern void ssh_aes_ctr_thread_destroy(EVP_CIPHER_CTX *ctx); */
65 /* extern void ssh_aes_ctr_thread_reconstruction(EVP_CIPHER_CTX *ctx); */
69 int number
; /* for ssh1 only */
72 u_int iv_len
; /* defaults to block_size */
76 #define CFLAG_CBC (1<<0)
77 #define CFLAG_CHACHAPOLY (1<<1)
78 #define CFLAG_AESCTR (1<<2)
79 #define CFLAG_NONE (1<<3)
81 const EVP_CIPHER
*(*evptype
)(void);
87 static struct sshcipher ciphers
[] = {
89 { "des", SSH_CIPHER_DES
, 8, 8, 0, 0, 0, 1, EVP_des_cbc
},
90 { "3des", SSH_CIPHER_3DES
, 8, 16, 0, 0, 0, 1, evp_ssh1_3des
},
91 { "blowfish", SSH_CIPHER_BLOWFISH
, 8, 32, 0, 0, 0, 1, evp_ssh1_bf
},
92 #endif /* WITH_SSH1 */
94 { "none", SSH_CIPHER_NONE
, 8, 0, 0, 0, 0, 0, EVP_enc_null
},
95 { "3des-cbc", SSH_CIPHER_SSH2
, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc
},
97 SSH_CIPHER_SSH2
, 8, 16, 0, 0, 0, 1, EVP_bf_cbc
},
99 SSH_CIPHER_SSH2
, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc
},
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 { "aes128-cbc", SSH_CIPHER_SSH2
, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc
},
104 { "aes192-cbc", SSH_CIPHER_SSH2
, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc
},
105 { "aes256-cbc", SSH_CIPHER_SSH2
, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc
},
106 { "rijndael-cbc@lysator.liu.se",
107 SSH_CIPHER_SSH2
, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc
},
108 { "aes128-ctr", SSH_CIPHER_SSH2
, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr
},
109 { "aes192-ctr", SSH_CIPHER_SSH2
, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr
},
110 { "aes256-ctr", SSH_CIPHER_SSH2
, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr
},
111 # ifdef OPENSSL_HAVE_EVPGCM
112 { "aes128-gcm@openssh.com",
113 SSH_CIPHER_SSH2
, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm
},
114 { "aes256-gcm@openssh.com",
115 SSH_CIPHER_SSH2
, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm
},
116 # endif /* OPENSSL_HAVE_EVPGCM */
117 #else /* WITH_OPENSSL */
118 { "aes128-ctr", SSH_CIPHER_SSH2
, 16, 16, 0, 0, 0, CFLAG_AESCTR
, NULL
},
119 { "aes192-ctr", SSH_CIPHER_SSH2
, 16, 24, 0, 0, 0, CFLAG_AESCTR
, NULL
},
120 { "aes256-ctr", SSH_CIPHER_SSH2
, 16, 32, 0, 0, 0, CFLAG_AESCTR
, NULL
},
121 { "none", SSH_CIPHER_NONE
, 8, 0, 0, 0, 0, CFLAG_NONE
, NULL
},
122 #endif /* WITH_OPENSSL */
123 { "chacha20-poly1305@openssh.com",
124 SSH_CIPHER_SSH2
, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY
, NULL
},
126 { NULL
, SSH_CIPHER_INVALID
, 0, 0, 0, 0, 0, 0, NULL
}
131 /* used to get the cipher name so when force rekeying to handle the
132 * single to multithreaded ctr cipher swap we only rekey when appropriate
135 cipher_return_name(const struct sshcipher
*c
)
140 /* in order to get around sandbox and forking issues with a threaded cipher
141 * we set the initial pre-auth aes-ctr cipher to the default OpenSSH cipher
142 * post auth we set them to the new evp as defined by cipher-ctr-mt
146 cipher_reset_multithreaded()
148 (cipher_by_name("aes128-ctr"))->evptype
= evp_aes_ctr_mt
;
149 (cipher_by_name("aes192-ctr"))->evptype
= evp_aes_ctr_mt
;
150 (cipher_by_name("aes256-ctr"))->evptype
= evp_aes_ctr_mt
;
154 /* Returns a comma-separated list of supported ciphers. */
156 cipher_alg_list(char sep
, int auth_only
)
158 char *tmp
, *ret
= NULL
;
159 size_t nlen
, rlen
= 0;
160 const struct sshcipher
*c
;
162 for (c
= ciphers
; c
->name
!= NULL
; c
++) {
163 if (c
->number
!= SSH_CIPHER_SSH2
)
165 if (auth_only
&& c
->auth_len
== 0)
169 nlen
= strlen(c
->name
);
170 if ((tmp
= realloc(ret
, rlen
+ nlen
+ 2)) == NULL
) {
175 memcpy(ret
+ rlen
, c
->name
, nlen
+ 1);
182 cipher_blocksize(const struct sshcipher
*c
)
184 return (c
->block_size
);
188 cipher_keylen(const struct sshcipher
*c
)
194 cipher_seclen(const struct sshcipher
*c
)
196 if (strcmp("3des-cbc", c
->name
) == 0)
198 return cipher_keylen(c
);
202 cipher_authlen(const struct sshcipher
*c
)
204 return (c
->auth_len
);
208 cipher_ivlen(const struct sshcipher
*c
)
211 * Default is cipher block size, except for chacha20+poly1305 that
212 * needs no IV. XXX make iv_len == -1 default?
214 return (c
->iv_len
!= 0 || (c
->flags
& CFLAG_CHACHAPOLY
) != 0) ?
215 c
->iv_len
: c
->block_size
;
219 cipher_get_number(const struct sshcipher
*c
)
225 cipher_is_cbc(const struct sshcipher
*c
)
227 return (c
->flags
& CFLAG_CBC
) != 0;
231 cipher_mask_ssh1(int client
)
234 mask
|= 1 << SSH_CIPHER_3DES
; /* Mandatory */
235 mask
|= 1 << SSH_CIPHER_BLOWFISH
;
237 mask
|= 1 << SSH_CIPHER_DES
;
243 cipher_by_name(const char *name
)
246 for (c
= ciphers
; c
->name
!= NULL
; c
++)
247 if (strcmp(c
->name
, name
) == 0)
252 const struct sshcipher
*
253 cipher_by_number(int id
)
256 for (c
= ciphers
; c
->name
!= NULL
; c
++)
262 #define CIPHER_SEP ","
264 ciphers_valid(const char *names
)
266 const struct sshcipher
*c
;
267 char *cipher_list
, *cp
;
270 if (names
== NULL
|| strcmp(names
, "") == 0)
272 if ((cipher_list
= cp
= strdup(names
)) == NULL
)
274 for ((p
= strsep(&cp
, CIPHER_SEP
)); p
&& *p
!= '\0';
275 (p
= strsep(&cp
, CIPHER_SEP
))) {
276 c
= cipher_by_name(p
);
277 if (c
== NULL
|| (c
->number
!= SSH_CIPHER_SSH2
&&
278 c
->number
!= SSH_CIPHER_NONE
)) {
288 * Parses the name of the cipher. Returns the number of the corresponding
289 * cipher, or -1 on error.
293 cipher_number(const char *name
)
295 const struct sshcipher
*c
;
298 for (c
= ciphers
; c
->name
!= NULL
; c
++)
299 if (strcasecmp(c
->name
, name
) == 0)
307 const struct sshcipher
*c
= cipher_by_number(id
);
308 return (c
==NULL
) ? "<unknown>" : c
->name
;
312 cipher_warning_message(const struct sshcipher_ctx
*cc
)
314 if (cc
== NULL
|| cc
->cipher
== NULL
)
316 if (cc
->cipher
->number
== SSH_CIPHER_DES
)
317 return "use of DES is strongly discouraged due to "
318 "cryptographic weaknesses";
323 cipher_init(struct sshcipher_ctx
*cc
, const struct sshcipher
*cipher
,
324 const u_char
*key
, u_int keylen
, const u_char
*iv
, u_int ivlen
,
328 int ret
= SSH_ERR_INTERNAL_ERROR
;
329 const EVP_CIPHER
*type
;
331 u_char
*junk
, *discard
;
333 if (cipher
->number
== SSH_CIPHER_DES
) {
338 cc
->plaintext
= (cipher
->number
== SSH_CIPHER_NONE
);
339 cc
->encrypt
= do_encrypt
;
341 if (keylen
< cipher
->key_len
||
342 (iv
!= NULL
&& ivlen
< cipher_ivlen(cipher
)))
343 return SSH_ERR_INVALID_ARGUMENT
;
346 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
347 return chachapoly_init(&cc
->cp_ctx
, key
, keylen
);
350 if ((cc
->cipher
->flags
& CFLAG_AESCTR
) != 0) {
351 aesctr_keysetup(&cc
->ac_ctx
, key
, 8 * keylen
, 8 * ivlen
);
352 aesctr_ivsetup(&cc
->ac_ctx
, iv
);
355 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
357 return SSH_ERR_INVALID_ARGUMENT
;
359 type
= (*cipher
->evptype
)();
360 EVP_CIPHER_CTX_init(&cc
->evp
);
361 if (EVP_CipherInit(&cc
->evp
, type
, NULL
, (u_char
*)iv
,
362 (do_encrypt
== CIPHER_ENCRYPT
)) == 0) {
363 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
366 if (cipher_authlen(cipher
) &&
367 !EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_SET_IV_FIXED
,
369 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
372 klen
= EVP_CIPHER_CTX_key_length(&cc
->evp
);
373 if (klen
> 0 && keylen
!= (u_int
)klen
) {
374 if (EVP_CIPHER_CTX_set_key_length(&cc
->evp
, keylen
) == 0) {
375 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
379 if (EVP_CipherInit(&cc
->evp
, NULL
, (u_char
*)key
, NULL
, -1) == 0) {
380 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
384 if (cipher
->discard_len
> 0) {
385 if ((junk
= malloc(cipher
->discard_len
)) == NULL
||
386 (discard
= malloc(cipher
->discard_len
)) == NULL
) {
389 ret
= SSH_ERR_ALLOC_FAIL
;
392 ret
= EVP_Cipher(&cc
->evp
, discard
, junk
, cipher
->discard_len
);
393 explicit_bzero(discard
, cipher
->discard_len
);
397 ret
= SSH_ERR_LIBCRYPTO_ERROR
;
399 EVP_CIPHER_CTX_cleanup(&cc
->evp
);
408 * cipher_crypt() operates as following:
409 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
410 * Theses bytes are treated as additional authenticated data for
411 * authenticated encryption modes.
412 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
413 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
414 * This tag is written on encryption and verified on decryption.
415 * Both 'aadlen' and 'authlen' can be set to 0.
418 cipher_crypt(struct sshcipher_ctx
*cc
, u_int seqnr
, u_char
*dest
,
419 const u_char
*src
, u_int len
, u_int aadlen
, u_int authlen
)
421 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
422 return chachapoly_crypt(&cc
->cp_ctx
, seqnr
, dest
, src
,
423 len
, aadlen
, authlen
, cc
->encrypt
);
426 if ((cc
->cipher
->flags
& CFLAG_AESCTR
) != 0) {
428 memcpy(dest
, src
, aadlen
);
429 aesctr_encrypt_bytes(&cc
->ac_ctx
, src
+ aadlen
,
433 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0) {
434 memcpy(dest
, src
, aadlen
+ len
);
437 return SSH_ERR_INVALID_ARGUMENT
;
442 if (authlen
!= cipher_authlen(cc
->cipher
))
443 return SSH_ERR_INVALID_ARGUMENT
;
445 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_IV_GEN
,
447 return SSH_ERR_LIBCRYPTO_ERROR
;
448 /* set tag on decyption */
450 !EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_SET_TAG
,
451 authlen
, (u_char
*)src
+ aadlen
+ len
))
452 return SSH_ERR_LIBCRYPTO_ERROR
;
456 EVP_Cipher(&cc
->evp
, NULL
, (u_char
*)src
, aadlen
) < 0)
457 return SSH_ERR_LIBCRYPTO_ERROR
;
458 memcpy(dest
, src
, aadlen
);
460 if (len
% cc
->cipher
->block_size
)
461 return SSH_ERR_INVALID_ARGUMENT
;
462 if (EVP_Cipher(&cc
->evp
, dest
+ aadlen
, (u_char
*)src
+ aadlen
,
464 return SSH_ERR_LIBCRYPTO_ERROR
;
466 /* compute tag (on encrypt) or verify tag (on decrypt) */
467 if (EVP_Cipher(&cc
->evp
, NULL
, NULL
, 0) < 0)
469 SSH_ERR_LIBCRYPTO_ERROR
: SSH_ERR_MAC_INVALID
;
471 !EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_GET_TAG
,
472 authlen
, dest
+ aadlen
+ len
))
473 return SSH_ERR_LIBCRYPTO_ERROR
;
479 /* Extract the packet length, including any decryption necessary beforehand */
481 cipher_get_length(struct sshcipher_ctx
*cc
, u_int
*plenp
, u_int seqnr
,
482 const u_char
*cp
, u_int len
)
484 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
485 return chachapoly_get_length(&cc
->cp_ctx
, plenp
, seqnr
,
488 return SSH_ERR_MESSAGE_INCOMPLETE
;
489 *plenp
= get_u32(cp
);
494 cipher_cleanup(struct sshcipher_ctx
*cc
)
496 if (cc
== NULL
|| cc
->cipher
== NULL
)
498 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
499 explicit_bzero(&cc
->cp_ctx
, sizeof(cc
->cp_ctx
));
500 else if ((cc
->cipher
->flags
& CFLAG_AESCTR
) != 0)
501 explicit_bzero(&cc
->ac_ctx
, sizeof(cc
->ac_ctx
));
503 else if (EVP_CIPHER_CTX_cleanup(&cc
->evp
) == 0)
504 return SSH_ERR_LIBCRYPTO_ERROR
;
510 * Selects the cipher, and keys if by computing the MD5 checksum of the
511 * passphrase and using the resulting 16 bytes as the key.
514 cipher_set_key_string(struct sshcipher_ctx
*cc
, const struct sshcipher
*cipher
,
515 const char *passphrase
, int do_encrypt
)
518 int r
= SSH_ERR_INTERNAL_ERROR
;
520 if ((r
= ssh_digest_memory(SSH_DIGEST_MD5
,
521 passphrase
, strlen(passphrase
),
522 digest
, sizeof(digest
))) != 0)
525 r
= cipher_init(cc
, cipher
, digest
, 16, NULL
, 0, do_encrypt
);
527 explicit_bzero(digest
, sizeof(digest
));
532 * Exports an IV from the sshcipher_ctx required to export the key
533 * state back from the unprivileged child to the privileged parent
537 cipher_get_keyiv_len(const struct sshcipher_ctx
*cc
)
539 const struct sshcipher
*c
= cc
->cipher
;
542 if (c
->number
== SSH_CIPHER_3DES
)
544 else if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
548 ivlen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
549 #endif /* WITH_OPENSSL */
554 cipher_get_keyiv(struct sshcipher_ctx
*cc
, u_char
*iv
, u_int len
)
556 const struct sshcipher
*c
= cc
->cipher
;
561 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0) {
563 return SSH_ERR_INVALID_ARGUMENT
;
566 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
571 case SSH_CIPHER_NONE
:
572 case SSH_CIPHER_SSH2
:
574 case SSH_CIPHER_BLOWFISH
:
575 evplen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
579 return SSH_ERR_LIBCRYPTO_ERROR
;
580 if ((u_int
)evplen
!= len
)
581 return SSH_ERR_INVALID_ARGUMENT
;
582 #ifndef OPENSSL_HAVE_EVPCTR
583 if (c
->evptype
== evp_aes_128_ctr
)
584 ssh_aes_ctr_iv(&cc
->evp
, 0, iv
, len
);
587 if (cipher_authlen(c
)) {
588 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
, EVP_CTRL_GCM_IV_GEN
,
590 return SSH_ERR_LIBCRYPTO_ERROR
;
592 memcpy(iv
, cc
->evp
.iv
, len
);
596 case SSH_CIPHER_3DES
:
597 return ssh1_3des_iv(&cc
->evp
, 0, iv
, 24);
600 return SSH_ERR_INVALID_ARGUMENT
;
606 cipher_set_keyiv(struct sshcipher_ctx
*cc
, const u_char
*iv
)
608 const struct sshcipher
*c
= cc
->cipher
;
613 if ((cc
->cipher
->flags
& CFLAG_CHACHAPOLY
) != 0)
615 if ((cc
->cipher
->flags
& CFLAG_NONE
) != 0)
620 case SSH_CIPHER_NONE
:
621 case SSH_CIPHER_SSH2
:
623 case SSH_CIPHER_BLOWFISH
:
624 evplen
= EVP_CIPHER_CTX_iv_length(&cc
->evp
);
626 return SSH_ERR_LIBCRYPTO_ERROR
;
627 if (cipher_authlen(c
)) {
628 /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
629 if (!EVP_CIPHER_CTX_ctrl(&cc
->evp
,
630 EVP_CTRL_GCM_SET_IV_FIXED
, -1, (void *)iv
))
631 return SSH_ERR_LIBCRYPTO_ERROR
;
633 memcpy(cc
->evp
.iv
, iv
, evplen
);
637 case SSH_CIPHER_3DES
:
638 return ssh1_3des_iv(&cc
->evp
, 1, (u_char
*)iv
, 24);
641 return SSH_ERR_INVALID_ARGUMENT
;
647 #define EVP_X_STATE(evp) (evp).cipher_data
648 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
652 cipher_get_keycontext(const struct sshcipher_ctx
*cc
, u_char
*dat
)
655 const struct sshcipher
*c
= cc
->cipher
;
658 if (c
->evptype
== EVP_rc4
) {
659 plen
= EVP_X_STATE_LEN(cc
->evp
);
662 memcpy(dat
, EVP_X_STATE(cc
->evp
), plen
);
671 cipher_set_keycontext(struct sshcipher_ctx
*cc
, const u_char
*dat
)
674 const struct sshcipher
*c
= cc
->cipher
;
677 if (c
->evptype
== EVP_rc4
) {
678 plen
= EVP_X_STATE_LEN(cc
->evp
);
679 memcpy(EVP_X_STATE(cc
->evp
), dat
, plen
);