1 /* $OpenBSD: cipher.c,v 1.111 2018/02/23 15:58:37 markus 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 struct sshcipher_ctx {
59 struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
60 struct aesctr_ctx ac_ctx; /* XXX union with evp? */
61 const struct sshcipher *cipher;
68 u_int iv_len; /* defaults to block_size */
71 #define CFLAG_CBC (1<<0)
72 #define CFLAG_CHACHAPOLY (1<<1)
73 #define CFLAG_AESCTR (1<<2)
74 #define CFLAG_NONE (1<<3)
75 #define CFLAG_INTERNAL CFLAG_NONE /* Don't use "none" for packets */
77 const EVP_CIPHER *(*evptype)(void);
83 static const struct sshcipher ciphers[] = {
85 #ifndef OPENSSL_NO_DES
86 { "3des-cbc", 8, 24, 0, 0, CFLAG_CBC, EVP_des_ede3_cbc },
88 { "aes128-cbc", 16, 16, 0, 0, CFLAG_CBC, EVP_aes_128_cbc },
89 { "aes192-cbc", 16, 24, 0, 0, CFLAG_CBC, EVP_aes_192_cbc },
90 { "aes256-cbc", 16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
91 { "rijndael-cbc@lysator.liu.se",
92 16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
93 { "aes128-ctr", 16, 16, 0, 0, 0, EVP_aes_128_ctr },
94 { "aes192-ctr", 16, 24, 0, 0, 0, EVP_aes_192_ctr },
95 { "aes256-ctr", 16, 32, 0, 0, 0, EVP_aes_256_ctr },
96 # ifdef OPENSSL_HAVE_EVPGCM
97 { "aes128-gcm@openssh.com",
98 16, 16, 12, 16, 0, EVP_aes_128_gcm },
99 { "aes256-gcm@openssh.com",
100 16, 32, 12, 16, 0, EVP_aes_256_gcm },
101 # endif /* OPENSSL_HAVE_EVPGCM */
103 { "aes128-ctr", 16, 16, 0, 0, CFLAG_AESCTR, NULL },
104 { "aes192-ctr", 16, 24, 0, 0, CFLAG_AESCTR, NULL },
105 { "aes256-ctr", 16, 32, 0, 0, CFLAG_AESCTR, NULL },
107 { "chacha20-poly1305@openssh.com",
108 8, 64, 0, 16, CFLAG_CHACHAPOLY, NULL },
109 { "none", 8, 0, 0, 0, CFLAG_NONE, NULL },
111 { NULL, 0, 0, 0, 0, 0, NULL }
116 /* Returns a comma-separated list of supported ciphers. */
118 cipher_alg_list(char sep, int auth_only)
120 char *tmp, *ret = NULL;
121 size_t nlen, rlen = 0;
122 const struct sshcipher *c;
124 for (c = ciphers; c->name != NULL; c++) {
125 if ((c->flags & CFLAG_INTERNAL) != 0)
127 if (auth_only && c->auth_len == 0)
131 nlen = strlen(c->name);
132 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
137 memcpy(ret + rlen, c->name, nlen + 1);
144 cipher_blocksize(const struct sshcipher *c)
146 return (c->block_size);
150 cipher_keylen(const struct sshcipher *c)
156 cipher_seclen(const struct sshcipher *c)
158 if (strcmp("3des-cbc", c->name) == 0)
160 return cipher_keylen(c);
164 cipher_authlen(const struct sshcipher *c)
166 return (c->auth_len);
170 cipher_ivlen(const struct sshcipher *c)
173 * Default is cipher block size, except for chacha20+poly1305 that
174 * needs no IV. XXX make iv_len == -1 default?
176 return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
177 c->iv_len : c->block_size;
181 cipher_is_cbc(const struct sshcipher *c)
183 return (c->flags & CFLAG_CBC) != 0;
187 cipher_ctx_is_plaintext(struct sshcipher_ctx *cc)
189 return cc->plaintext;
192 const struct sshcipher *
193 cipher_by_name(const char *name)
195 const struct sshcipher *c;
196 for (c = ciphers; c->name != NULL; c++)
197 if (strcmp(c->name, name) == 0)
202 #define CIPHER_SEP ","
204 ciphers_valid(const char *names)
206 const struct sshcipher *c;
207 char *cipher_list, *cp;
210 if (names == NULL || strcmp(names, "") == 0)
212 if ((cipher_list = cp = strdup(names)) == NULL)
214 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
215 (p = strsep(&cp, CIPHER_SEP))) {
216 c = cipher_by_name(p);
217 if (c == NULL || (c->flags & CFLAG_INTERNAL) != 0) {
227 cipher_warning_message(const struct sshcipher_ctx *cc)
229 if (cc == NULL || cc->cipher == NULL)
231 /* XXX repurpose for CBC warning */
236 cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher,
237 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
240 struct sshcipher_ctx *cc = NULL;
241 int ret = SSH_ERR_INTERNAL_ERROR;
243 const EVP_CIPHER *type;
248 if ((cc = calloc(sizeof(*cc), 1)) == NULL)
249 return SSH_ERR_ALLOC_FAIL;
251 cc->plaintext = (cipher->flags & CFLAG_NONE) != 0;
252 cc->encrypt = do_encrypt;
254 if (keylen < cipher->key_len ||
255 (iv != NULL && ivlen < cipher_ivlen(cipher))) {
256 ret = SSH_ERR_INVALID_ARGUMENT;
261 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
262 ret = chachapoly_init(&cc->cp_ctx, key, keylen);
265 if ((cc->cipher->flags & CFLAG_NONE) != 0) {
270 if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
271 aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
272 aesctr_ivsetup(&cc->ac_ctx, iv);
276 ret = SSH_ERR_INVALID_ARGUMENT;
278 #else /* WITH_OPENSSL */
279 type = (*cipher->evptype)();
280 if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) {
281 ret = SSH_ERR_ALLOC_FAIL;
284 if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv,
285 (do_encrypt == CIPHER_ENCRYPT)) == 0) {
286 ret = SSH_ERR_LIBCRYPTO_ERROR;
289 if (cipher_authlen(cipher) &&
290 !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
292 ret = SSH_ERR_LIBCRYPTO_ERROR;
295 klen = EVP_CIPHER_CTX_key_length(cc->evp);
296 if (klen > 0 && keylen != (u_int)klen) {
297 if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) {
298 ret = SSH_ERR_LIBCRYPTO_ERROR;
302 if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
303 ret = SSH_ERR_LIBCRYPTO_ERROR;
307 #endif /* WITH_OPENSSL */
315 EVP_CIPHER_CTX_free(cc->evp);
316 #endif /* WITH_OPENSSL */
317 explicit_bzero(cc, sizeof(*cc));
325 * cipher_crypt() operates as following:
326 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
327 * Theses bytes are treated as additional authenticated data for
328 * authenticated encryption modes.
329 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
330 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
331 * This tag is written on encryption and verified on decryption.
332 * Both 'aadlen' and 'authlen' can be set to 0.
335 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
336 const u_char *src, u_int len, u_int aadlen, u_int authlen)
338 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
339 return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
340 len, aadlen, authlen, cc->encrypt);
342 if ((cc->cipher->flags & CFLAG_NONE) != 0) {
343 memcpy(dest, src, aadlen + len);
347 if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
349 memcpy(dest, src, aadlen);
350 aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
354 return SSH_ERR_INVALID_ARGUMENT;
359 if (authlen != cipher_authlen(cc->cipher))
360 return SSH_ERR_INVALID_ARGUMENT;
362 if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
364 return SSH_ERR_LIBCRYPTO_ERROR;
365 /* set tag on decyption */
367 !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG,
368 authlen, (u_char *)src + aadlen + len))
369 return SSH_ERR_LIBCRYPTO_ERROR;
373 EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0)
374 return SSH_ERR_LIBCRYPTO_ERROR;
375 memcpy(dest, src, aadlen);
377 if (len % cc->cipher->block_size)
378 return SSH_ERR_INVALID_ARGUMENT;
379 if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen,
381 return SSH_ERR_LIBCRYPTO_ERROR;
383 /* compute tag (on encrypt) or verify tag (on decrypt) */
384 if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0)
386 SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
388 !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG,
389 authlen, dest + aadlen + len))
390 return SSH_ERR_LIBCRYPTO_ERROR;
396 /* Extract the packet length, including any decryption necessary beforehand */
398 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
399 const u_char *cp, u_int len)
401 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
402 return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
405 return SSH_ERR_MESSAGE_INCOMPLETE;
406 *plenp = PEEK_U32(cp);
411 cipher_free(struct sshcipher_ctx *cc)
415 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
416 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
417 else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
418 explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
420 EVP_CIPHER_CTX_free(cc->evp);
423 explicit_bzero(cc, sizeof(*cc));
428 * Exports an IV from the sshcipher_ctx required to export the key
429 * state back from the unprivileged child to the privileged parent
433 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
435 const struct sshcipher *c = cc->cipher;
437 if ((c->flags & CFLAG_CHACHAPOLY) != 0)
439 else if ((c->flags & CFLAG_AESCTR) != 0)
440 return sizeof(cc->ac_ctx.ctr);
442 return EVP_CIPHER_CTX_iv_length(cc->evp);
449 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, size_t len)
452 const struct sshcipher *c = cc->cipher;
456 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
458 return SSH_ERR_INVALID_ARGUMENT;
461 if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
462 if (len != sizeof(cc->ac_ctx.ctr))
463 return SSH_ERR_INVALID_ARGUMENT;
464 memcpy(iv, cc->ac_ctx.ctr, len);
467 if ((cc->cipher->flags & CFLAG_NONE) != 0)
471 evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
475 return SSH_ERR_LIBCRYPTO_ERROR;
476 if ((size_t)evplen != len)
477 return SSH_ERR_INVALID_ARGUMENT;
478 #ifndef OPENSSL_HAVE_EVPCTR
479 if (c->evptype == evp_aes_128_ctr)
480 ssh_aes_ctr_iv(cc->evp, 0, iv, len);
483 if (cipher_authlen(c)) {
484 if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
486 return SSH_ERR_LIBCRYPTO_ERROR;
487 } else if (!EVP_CIPHER_CTX_get_iv(cc->evp, iv, len))
488 return SSH_ERR_LIBCRYPTO_ERROR;
494 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv, size_t len)
497 const struct sshcipher *c = cc->cipher;
501 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
503 if ((cc->cipher->flags & CFLAG_NONE) != 0)
507 evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
509 return SSH_ERR_LIBCRYPTO_ERROR;
510 if ((size_t)evplen != len)
511 return SSH_ERR_INVALID_ARGUMENT;
512 #ifndef OPENSSL_HAVE_EVPCTR
513 /* XXX iv arg is const, but ssh_aes_ctr_iv isn't */
514 if (c->evptype == evp_aes_128_ctr)
515 ssh_aes_ctr_iv(cc->evp, 1, (u_char *)iv, evplen);
518 if (cipher_authlen(c)) {
519 /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
520 if (!EVP_CIPHER_CTX_ctrl(cc->evp,
521 EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
522 return SSH_ERR_LIBCRYPTO_ERROR;
523 } else if (!EVP_CIPHER_CTX_set_iv(cc->evp, iv, evplen))
524 return SSH_ERR_LIBCRYPTO_ERROR;