1 /* $OpenBSD: cipher.c,v 1.80 2006/07/22 20:48:22 stevesk 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 <openssl/md5.h>
48 /* compatibility with old or broken OpenSSL versions */
49 #include "openbsd-compat/openssl-compat.h"
51 extern const EVP_CIPHER *evp_ssh1_bf(void);
52 extern const EVP_CIPHER *evp_ssh1_3des(void);
53 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
54 extern const EVP_CIPHER *evp_aes_128_ctr(void);
55 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
59 int number; /* for ssh1 only */
63 const EVP_CIPHER *(*evptype)(void);
65 { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
66 { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
67 { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
68 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
70 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
71 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
72 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
73 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
74 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
75 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
76 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
77 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
78 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
79 { "rijndael-cbc@lysator.liu.se",
80 SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
81 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
82 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
83 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
84 #ifdef USE_CIPHER_ACSS
85 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
87 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL }
93 cipher_blocksize(const Cipher *c)
95 return (c->block_size);
99 cipher_keylen(const Cipher *c)
105 cipher_get_number(const Cipher *c)
111 cipher_mask_ssh1(int client)
114 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
115 mask |= 1 << SSH_CIPHER_BLOWFISH;
117 mask |= 1 << SSH_CIPHER_DES;
123 cipher_by_name(const char *name)
126 for (c = ciphers; c->name != NULL; c++)
127 if (strcmp(c->name, name) == 0)
133 cipher_by_number(int id)
136 for (c = ciphers; c->name != NULL; c++)
142 #define CIPHER_SEP ","
144 ciphers_valid(const char *names)
147 char *cipher_list, *cp;
150 if (names == NULL || strcmp(names, "") == 0)
152 cipher_list = cp = xstrdup(names);
153 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
154 (p = strsep(&cp, CIPHER_SEP))) {
155 c = cipher_by_name(p);
156 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
157 debug("bad cipher %s [%s]", p, names);
161 debug3("cipher ok: %s [%s]", p, names);
164 debug3("ciphers ok: [%s]", names);
170 * Parses the name of the cipher. Returns the number of the corresponding
171 * cipher, or -1 on error.
175 cipher_number(const char *name)
180 for (c = ciphers; c->name != NULL; c++)
181 if (strcasecmp(c->name, name) == 0)
189 Cipher *c = cipher_by_number(id);
190 return (c==NULL) ? "<unknown>" : c->name;
194 cipher_init(CipherContext *cc, Cipher *cipher,
195 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
198 static int dowarn = 1;
202 const EVP_CIPHER *type;
205 u_char *junk, *discard;
207 if (cipher->number == SSH_CIPHER_DES) {
209 error("Warning: use of DES is strongly discouraged "
210 "due to cryptographic weaknesses");
216 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
218 if (keylen < cipher->key_len)
219 fatal("cipher_init: key length %d is insufficient for %s.",
220 keylen, cipher->name);
221 if (iv != NULL && ivlen < cipher->block_size)
222 fatal("cipher_init: iv length %d is insufficient for %s.",
223 ivlen, cipher->name);
226 type = (*cipher->evptype)();
228 EVP_CIPHER_CTX_init(&cc->evp);
230 if (type->key_len > 0 && type->key_len != keylen) {
231 debug("cipher_init: set keylen (%d -> %d)",
232 type->key_len, keylen);
233 type->key_len = keylen;
235 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
236 (do_encrypt == CIPHER_ENCRYPT));
238 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
239 (do_encrypt == CIPHER_ENCRYPT)) == 0)
240 fatal("cipher_init: EVP_CipherInit failed for %s",
242 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
243 if (klen > 0 && keylen != (u_int)klen) {
244 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
245 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
246 fatal("cipher_init: set keylen failed (%d -> %d)",
249 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
250 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
254 if (cipher->discard_len > 0) {
255 junk = xmalloc(cipher->discard_len);
256 discard = xmalloc(cipher->discard_len);
257 if (EVP_Cipher(&cc->evp, discard, junk,
258 cipher->discard_len) == 0)
259 fatal("evp_crypt: EVP_Cipher failed during discard");
260 memset(discard, 0, cipher->discard_len);
267 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
269 if (len % cc->cipher->block_size)
270 fatal("cipher_encrypt: bad plaintext length %d", len);
271 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
272 fatal("evp_crypt: EVP_Cipher failed");
276 cipher_cleanup(CipherContext *cc)
278 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
279 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
283 * Selects the cipher, and keys if by computing the MD5 checksum of the
284 * passphrase and using the resulting 16 bytes as the key.
288 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
289 const char *passphrase, int do_encrypt)
295 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
296 MD5_Final(digest, &md);
298 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
300 memset(digest, 0, sizeof(digest));
301 memset(&md, 0, sizeof(md));
305 * Exports an IV from the CipherContext required to export the key
306 * state back from the unprivileged child to the privileged parent
311 cipher_get_keyiv_len(const CipherContext *cc)
313 Cipher *c = cc->cipher;
316 if (c->number == SSH_CIPHER_3DES)
319 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
324 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
326 Cipher *c = cc->cipher;
330 case SSH_CIPHER_SSH2:
332 case SSH_CIPHER_BLOWFISH:
333 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
336 if ((u_int)evplen != len)
337 fatal("%s: wrong iv length %d != %d", __func__,
339 #ifdef USE_BUILTIN_RIJNDAEL
340 if (c->evptype == evp_rijndael)
341 ssh_rijndael_iv(&cc->evp, 0, iv, len);
344 if (c->evptype == evp_aes_128_ctr)
345 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
347 memcpy(iv, cc->evp.iv, len);
349 case SSH_CIPHER_3DES:
350 ssh1_3des_iv(&cc->evp, 0, iv, 24);
353 fatal("%s: bad cipher %d", __func__, c->number);
358 cipher_set_keyiv(CipherContext *cc, u_char *iv)
360 Cipher *c = cc->cipher;
364 case SSH_CIPHER_SSH2:
366 case SSH_CIPHER_BLOWFISH:
367 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
370 #ifdef USE_BUILTIN_RIJNDAEL
371 if (c->evptype == evp_rijndael)
372 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
375 if (c->evptype == evp_aes_128_ctr)
376 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
378 memcpy(cc->evp.iv, iv, evplen);
380 case SSH_CIPHER_3DES:
381 ssh1_3des_iv(&cc->evp, 1, iv, 24);
384 fatal("%s: bad cipher %d", __func__, c->number);
388 #if OPENSSL_VERSION_NUMBER < 0x00907000L
389 #define EVP_X_STATE(evp) &(evp).c
390 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
392 #define EVP_X_STATE(evp) (evp).cipher_data
393 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
397 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
399 Cipher *c = cc->cipher;
402 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
403 plen = EVP_X_STATE_LEN(cc->evp);
406 memcpy(dat, EVP_X_STATE(cc->evp), plen);
412 cipher_set_keycontext(CipherContext *cc, u_char *dat)
414 Cipher *c = cc->cipher;
417 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
418 plen = EVP_X_STATE_LEN(cc->evp);
419 memcpy(EVP_X_STATE(cc->evp), dat, plen);