1 /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
15 * Copyright (c) 1999 Niels Provos. All rights reserved.
16 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 #include <sys/types.h>
43 #include <openssl/md5.h>
52 /* compatibility with old or broken OpenSSL versions */
53 #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 void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
58 extern const EVP_CIPHER *evp_aes_128_ctr(void);
59 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
63 int number; /* for ssh1 only */
68 const EVP_CIPHER *(*evptype)(void);
70 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
71 { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
72 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
73 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
75 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
76 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
77 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
78 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
79 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
80 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
81 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
82 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
83 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
84 { "rijndael-cbc@lysator.liu.se",
85 SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
86 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr },
87 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr },
88 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr },
89 #ifdef USE_CIPHER_ACSS
90 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
92 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
98 cipher_blocksize(const Cipher *c)
100 return (c->block_size);
104 cipher_keylen(const Cipher *c)
110 cipher_get_number(const Cipher *c)
116 cipher_is_cbc(const Cipher *c)
118 return (c->cbc_mode);
122 cipher_mask_ssh1(int client)
125 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
126 mask |= 1 << SSH_CIPHER_BLOWFISH;
128 mask |= 1 << SSH_CIPHER_DES;
134 cipher_by_name(const char *name)
137 for (c = ciphers; c->name != NULL; c++)
138 if (strcmp(c->name, name) == 0)
144 cipher_by_number(int id)
147 for (c = ciphers; c->name != NULL; c++)
153 #define CIPHER_SEP ","
155 ciphers_valid(const char *names)
158 char *cipher_list, *cp;
161 if (names == NULL || strcmp(names, "") == 0)
163 cipher_list = cp = xstrdup(names);
164 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
165 (p = strsep(&cp, CIPHER_SEP))) {
166 c = cipher_by_name(p);
167 #ifdef NONE_CIPHER_ENABLED
168 if (c == NULL || (c->number != SSH_CIPHER_SSH2 &&
169 c->number != SSH_CIPHER_NONE)) {
171 if (c == NULL || (c->number != SSH_CIPHER_SSH2)) {
173 debug("bad cipher %s [%s]", p, names);
177 debug3("cipher ok: %s [%s]", p, names);
180 debug3("ciphers ok: [%s]", names);
186 * Parses the name of the cipher. Returns the number of the corresponding
187 * cipher, or -1 on error.
191 cipher_number(const char *name)
196 for (c = ciphers; c->name != NULL; c++)
197 if (strcasecmp(c->name, name) == 0)
205 Cipher *c = cipher_by_number(id);
206 return (c==NULL) ? "<unknown>" : c->name;
210 cipher_init(CipherContext *cc, Cipher *cipher,
211 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
214 static int dowarn = 1;
218 const EVP_CIPHER *type;
221 u_char *junk, *discard;
223 if (cipher->number == SSH_CIPHER_DES) {
225 error("Warning: use of DES is strongly discouraged "
226 "due to cryptographic weaknesses");
232 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
234 if (keylen < cipher->key_len)
235 fatal("cipher_init: key length %d is insufficient for %s.",
236 keylen, cipher->name);
237 if (iv != NULL && ivlen < cipher->block_size)
238 fatal("cipher_init: iv length %d is insufficient for %s.",
239 ivlen, cipher->name);
242 type = (*cipher->evptype)();
244 EVP_CIPHER_CTX_init(&cc->evp);
246 if (type->key_len > 0 && type->key_len != keylen) {
247 debug("cipher_init: set keylen (%d -> %d)",
248 type->key_len, keylen);
249 type->key_len = keylen;
251 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
252 (do_encrypt == CIPHER_ENCRYPT));
254 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
255 (do_encrypt == CIPHER_ENCRYPT)) == 0)
256 fatal("cipher_init: EVP_CipherInit failed for %s",
258 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
259 if (klen > 0 && keylen != (u_int)klen) {
260 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
261 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
262 fatal("cipher_init: set keylen failed (%d -> %d)",
265 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
266 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
270 if (cipher->discard_len > 0) {
271 junk = xmalloc(cipher->discard_len);
272 discard = xmalloc(cipher->discard_len);
273 if (EVP_Cipher(&cc->evp, discard, junk,
274 cipher->discard_len) == 0)
275 fatal("evp_crypt: EVP_Cipher failed during discard");
276 memset(discard, 0, cipher->discard_len);
283 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
285 if (len % cc->cipher->block_size)
286 fatal("cipher_encrypt: bad plaintext length %d", len);
287 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
288 fatal("evp_crypt: EVP_Cipher failed");
292 cipher_cleanup(CipherContext *cc)
294 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
295 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
299 * Selects the cipher, and keys if by computing the MD5 checksum of the
300 * passphrase and using the resulting 16 bytes as the key.
304 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
305 const char *passphrase, int do_encrypt)
311 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
312 MD5_Final(digest, &md);
314 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
316 memset(digest, 0, sizeof(digest));
317 memset(&md, 0, sizeof(md));
321 * Exports an IV from the CipherContext required to export the key
322 * state back from the unprivileged child to the privileged parent
327 cipher_get_keyiv_len(const CipherContext *cc)
329 Cipher *c = cc->cipher;
332 if (c->number == SSH_CIPHER_3DES)
335 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
340 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
342 Cipher *c = cc->cipher;
346 #ifdef NONE_CIPHER_ENABLED
347 case SSH_CIPHER_NONE:
349 case SSH_CIPHER_SSH2:
351 case SSH_CIPHER_BLOWFISH:
352 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
355 if ((u_int)evplen != len)
356 fatal("%s: wrong iv length %d != %d", __func__,
358 #ifdef USE_BUILTIN_RIJNDAEL
359 if (c->evptype == evp_rijndael)
360 ssh_rijndael_iv(&cc->evp, 0, iv, len);
363 if (c->evptype == evp_aes_128_ctr)
364 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
366 memcpy(iv, cc->evp.iv, len);
368 case SSH_CIPHER_3DES:
369 ssh1_3des_iv(&cc->evp, 0, iv, 24);
372 fatal("%s: bad cipher %d", __func__, c->number);
377 cipher_set_keyiv(CipherContext *cc, u_char *iv)
379 Cipher *c = cc->cipher;
383 #ifdef NONE_CIPHER_ENABLED
384 case SSH_CIPHER_NONE:
386 case SSH_CIPHER_SSH2:
388 case SSH_CIPHER_BLOWFISH:
389 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
392 #ifdef USE_BUILTIN_RIJNDAEL
393 if (c->evptype == evp_rijndael)
394 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
397 if (c->evptype == evp_aes_128_ctr)
398 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
400 memcpy(cc->evp.iv, iv, evplen);
402 case SSH_CIPHER_3DES:
403 ssh1_3des_iv(&cc->evp, 1, iv, 24);
406 fatal("%s: bad cipher %d", __func__, c->number);
410 #if OPENSSL_VERSION_NUMBER < 0x00907000L
411 #define EVP_X_STATE(evp) &(evp).c
412 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
414 #define EVP_X_STATE(evp) (evp).cipher_data
415 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
419 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
421 Cipher *c = cc->cipher;
424 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
425 plen = EVP_X_STATE_LEN(cc->evp);
428 memcpy(dat, EVP_X_STATE(cc->evp), plen);
434 cipher_set_keycontext(CipherContext *cc, u_char *dat)
436 Cipher *c = cc->cipher;
439 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
440 plen = EVP_X_STATE_LEN(cc->evp);
441 memcpy(EVP_X_STATE(cc->evp), dat, plen);