1 /* $OpenBSD: cipher.c,v 1.101 2015/12/10 17:08:40 mmcc 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) {
357 ret = SSH_ERR_ALLOC_FAIL;
360 ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
361 explicit_bzero(discard, cipher->discard_len);
365 ret = SSH_ERR_LIBCRYPTO_ERROR;
367 EVP_CIPHER_CTX_cleanup(&cc->evp);
376 * cipher_crypt() operates as following:
377 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
378 * Theses bytes are treated as additional authenticated data for
379 * authenticated encryption modes.
380 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
381 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
382 * This tag is written on encryption and verified on decryption.
383 * Both 'aadlen' and 'authlen' can be set to 0.
386 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
387 const u_char *src, u_int len, u_int aadlen, u_int authlen)
389 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
390 return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
391 len, aadlen, authlen, cc->encrypt);
394 if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
396 memcpy(dest, src, aadlen);
397 aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
401 if ((cc->cipher->flags & CFLAG_NONE) != 0) {
402 memcpy(dest, src, aadlen + len);
405 return SSH_ERR_INVALID_ARGUMENT;
410 if (authlen != cipher_authlen(cc->cipher))
411 return SSH_ERR_INVALID_ARGUMENT;
413 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
415 return SSH_ERR_LIBCRYPTO_ERROR;
416 /* set tag on decyption */
418 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
419 authlen, (u_char *)src + aadlen + len))
420 return SSH_ERR_LIBCRYPTO_ERROR;
424 EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
425 return SSH_ERR_LIBCRYPTO_ERROR;
426 memcpy(dest, src, aadlen);
428 if (len % cc->cipher->block_size)
429 return SSH_ERR_INVALID_ARGUMENT;
430 if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
432 return SSH_ERR_LIBCRYPTO_ERROR;
434 /* compute tag (on encrypt) or verify tag (on decrypt) */
435 if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
437 SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
439 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
440 authlen, dest + aadlen + len))
441 return SSH_ERR_LIBCRYPTO_ERROR;
447 /* Extract the packet length, including any decryption necessary beforehand */
449 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
450 const u_char *cp, u_int len)
452 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
453 return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
456 return SSH_ERR_MESSAGE_INCOMPLETE;
457 *plenp = get_u32(cp);
462 cipher_cleanup(struct sshcipher_ctx *cc)
464 if (cc == NULL || cc->cipher == NULL)
466 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
467 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
468 else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
469 explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
471 else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
472 return SSH_ERR_LIBCRYPTO_ERROR;
478 * Selects the cipher, and keys if by computing the MD5 checksum of the
479 * passphrase and using the resulting 16 bytes as the key.
482 cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
483 const char *passphrase, int do_encrypt)
486 int r = SSH_ERR_INTERNAL_ERROR;
488 if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
489 passphrase, strlen(passphrase),
490 digest, sizeof(digest))) != 0)
493 r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
495 explicit_bzero(digest, sizeof(digest));
500 * Exports an IV from the sshcipher_ctx required to export the key
501 * state back from the unprivileged child to the privileged parent
505 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
507 const struct sshcipher *c = cc->cipher;
510 if (c->number == SSH_CIPHER_3DES)
512 else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
514 else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
515 ivlen = sizeof(cc->ac_ctx.ctr);
518 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
519 #endif /* WITH_OPENSSL */
524 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
526 const struct sshcipher *c = cc->cipher;
531 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
533 return SSH_ERR_INVALID_ARGUMENT;
536 if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
537 if (len != sizeof(cc->ac_ctx.ctr))
538 return SSH_ERR_INVALID_ARGUMENT;
539 memcpy(iv, cc->ac_ctx.ctr, len);
542 if ((cc->cipher->flags & CFLAG_NONE) != 0)
547 case SSH_CIPHER_SSH2:
549 case SSH_CIPHER_BLOWFISH:
550 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
554 return SSH_ERR_LIBCRYPTO_ERROR;
555 if ((u_int)evplen != len)
556 return SSH_ERR_INVALID_ARGUMENT;
557 #ifndef OPENSSL_HAVE_EVPCTR
558 if (c->evptype == evp_aes_128_ctr)
559 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
562 if (cipher_authlen(c)) {
563 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
565 return SSH_ERR_LIBCRYPTO_ERROR;
567 memcpy(iv, cc->evp.iv, len);
571 case SSH_CIPHER_3DES:
572 return ssh1_3des_iv(&cc->evp, 0, iv, 24);
575 return SSH_ERR_INVALID_ARGUMENT;
581 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
583 const struct sshcipher *c = cc->cipher;
588 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
590 if ((cc->cipher->flags & CFLAG_NONE) != 0)
595 case SSH_CIPHER_SSH2:
597 case SSH_CIPHER_BLOWFISH:
598 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
600 return SSH_ERR_LIBCRYPTO_ERROR;
601 if (cipher_authlen(c)) {
602 /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
603 if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
604 EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
605 return SSH_ERR_LIBCRYPTO_ERROR;
607 memcpy(cc->evp.iv, iv, evplen);
611 case SSH_CIPHER_3DES:
612 return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
615 return SSH_ERR_INVALID_ARGUMENT;
621 #define EVP_X_STATE(evp) (evp).cipher_data
622 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
626 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
629 const struct sshcipher *c = cc->cipher;
632 if (c->evptype == EVP_rc4) {
633 plen = EVP_X_STATE_LEN(cc->evp);
636 memcpy(dat, EVP_X_STATE(cc->evp), plen);
645 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
648 const struct sshcipher *c = cc->cipher;
651 if (c->evptype == EVP_rc4) {
652 plen = EVP_X_STATE_LEN(cc->evp);
653 memcpy(EVP_X_STATE(cc->evp), dat, plen);