1 /* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt 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>
42 #include <openssl/md5.h>
51 /* compatibility with old or broken OpenSSL versions */
52 #include "openbsd-compat/openssl-compat.h"
54 extern const EVP_CIPHER *evp_ssh1_bf(void);
55 extern const EVP_CIPHER *evp_ssh1_3des(void);
56 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
57 extern const EVP_CIPHER *evp_aes_128_ctr(void);
58 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
62 int number; /* for ssh1 only */
66 const EVP_CIPHER *(*evptype)(void);
68 { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
69 { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
70 { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
71 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
73 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
74 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
75 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
76 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
77 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
78 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
79 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
80 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
81 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
82 { "rijndael-cbc@lysator.liu.se",
83 SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
84 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
85 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
86 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
87 #ifdef USE_CIPHER_ACSS
88 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
90 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL }
96 cipher_blocksize(const Cipher *c)
98 return (c->block_size);
102 cipher_keylen(const Cipher *c)
108 cipher_get_number(const Cipher *c)
114 cipher_mask_ssh1(int client)
117 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
118 mask |= 1 << SSH_CIPHER_BLOWFISH;
120 mask |= 1 << SSH_CIPHER_DES;
126 cipher_by_name(const char *name)
129 for (c = ciphers; c->name != NULL; c++)
130 if (strcmp(c->name, name) == 0)
136 cipher_by_number(int id)
139 for (c = ciphers; c->name != NULL; c++)
145 #define CIPHER_SEP ","
147 ciphers_valid(const char *names)
150 char *cipher_list, *cp;
153 if (names == NULL || strcmp(names, "") == 0)
155 cipher_list = cp = xstrdup(names);
156 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
157 (p = strsep(&cp, CIPHER_SEP))) {
158 c = cipher_by_name(p);
159 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
160 debug("bad cipher %s [%s]", p, names);
164 debug3("cipher ok: %s [%s]", p, names);
167 debug3("ciphers ok: [%s]", names);
173 * Parses the name of the cipher. Returns the number of the corresponding
174 * cipher, or -1 on error.
178 cipher_number(const char *name)
183 for (c = ciphers; c->name != NULL; c++)
184 if (strcasecmp(c->name, name) == 0)
192 Cipher *c = cipher_by_number(id);
193 return (c==NULL) ? "<unknown>" : c->name;
197 cipher_init(CipherContext *cc, Cipher *cipher,
198 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
201 static int dowarn = 1;
205 const EVP_CIPHER *type;
208 u_char *junk, *discard;
210 if (cipher->number == SSH_CIPHER_DES) {
212 error("Warning: use of DES is strongly discouraged "
213 "due to cryptographic weaknesses");
219 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
221 if (keylen < cipher->key_len)
222 fatal("cipher_init: key length %d is insufficient for %s.",
223 keylen, cipher->name);
224 if (iv != NULL && ivlen < cipher->block_size)
225 fatal("cipher_init: iv length %d is insufficient for %s.",
226 ivlen, cipher->name);
229 type = (*cipher->evptype)();
231 EVP_CIPHER_CTX_init(&cc->evp);
233 if (type->key_len > 0 && type->key_len != keylen) {
234 debug("cipher_init: set keylen (%d -> %d)",
235 type->key_len, keylen);
236 type->key_len = keylen;
238 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
239 (do_encrypt == CIPHER_ENCRYPT));
241 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
242 (do_encrypt == CIPHER_ENCRYPT)) == 0)
243 fatal("cipher_init: EVP_CipherInit failed for %s",
245 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
246 if (klen > 0 && keylen != (u_int)klen) {
247 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
248 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
249 fatal("cipher_init: set keylen failed (%d -> %d)",
252 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
253 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
257 if (cipher->discard_len > 0) {
258 junk = xmalloc(cipher->discard_len);
259 discard = xmalloc(cipher->discard_len);
260 if (EVP_Cipher(&cc->evp, discard, junk,
261 cipher->discard_len) == 0)
262 fatal("evp_crypt: EVP_Cipher failed during discard");
263 memset(discard, 0, cipher->discard_len);
270 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
272 if (len % cc->cipher->block_size)
273 fatal("cipher_encrypt: bad plaintext length %d", len);
274 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
275 fatal("evp_crypt: EVP_Cipher failed");
279 cipher_cleanup(CipherContext *cc)
281 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
282 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
286 * Selects the cipher, and keys if by computing the MD5 checksum of the
287 * passphrase and using the resulting 16 bytes as the key.
291 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
292 const char *passphrase, int do_encrypt)
298 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
299 MD5_Final(digest, &md);
301 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
303 memset(digest, 0, sizeof(digest));
304 memset(&md, 0, sizeof(md));
308 * Exports an IV from the CipherContext required to export the key
309 * state back from the unprivileged child to the privileged parent
314 cipher_get_keyiv_len(const CipherContext *cc)
316 Cipher *c = cc->cipher;
319 if (c->number == SSH_CIPHER_3DES)
322 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
327 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
329 Cipher *c = cc->cipher;
333 case SSH_CIPHER_SSH2:
335 case SSH_CIPHER_BLOWFISH:
336 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
339 if ((u_int)evplen != len)
340 fatal("%s: wrong iv length %d != %d", __func__,
342 #ifdef USE_BUILTIN_RIJNDAEL
343 if (c->evptype == evp_rijndael)
344 ssh_rijndael_iv(&cc->evp, 0, iv, len);
347 if (c->evptype == evp_aes_128_ctr)
348 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
350 memcpy(iv, cc->evp.iv, len);
352 case SSH_CIPHER_3DES:
353 ssh1_3des_iv(&cc->evp, 0, iv, 24);
356 fatal("%s: bad cipher %d", __func__, c->number);
361 cipher_set_keyiv(CipherContext *cc, u_char *iv)
363 Cipher *c = cc->cipher;
367 case SSH_CIPHER_SSH2:
369 case SSH_CIPHER_BLOWFISH:
370 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
373 #ifdef USE_BUILTIN_RIJNDAEL
374 if (c->evptype == evp_rijndael)
375 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
378 if (c->evptype == evp_aes_128_ctr)
379 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
381 memcpy(cc->evp.iv, iv, evplen);
383 case SSH_CIPHER_3DES:
384 ssh1_3des_iv(&cc->evp, 1, iv, 24);
387 fatal("%s: bad cipher %d", __func__, c->number);
391 #if OPENSSL_VERSION_NUMBER < 0x00907000L
392 #define EVP_X_STATE(evp) &(evp).c
393 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
395 #define EVP_X_STATE(evp) (evp).cipher_data
396 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
400 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
402 Cipher *c = cc->cipher;
405 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
406 plen = EVP_X_STATE_LEN(cc->evp);
409 memcpy(dat, EVP_X_STATE(cc->evp), plen);
415 cipher_set_keycontext(CipherContext *cc, u_char *dat)
417 Cipher *c = cc->cipher;
420 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
421 plen = EVP_X_STATE_LEN(cc->evp);
422 memcpy(EVP_X_STATE(cc->evp), dat, plen);