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);