1 /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 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>
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 */
67 const EVP_CIPHER *(*evptype)(void);
69 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
70 { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
71 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
72 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
74 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
75 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
76 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
77 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
78 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
79 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
80 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
81 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
82 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
83 { "rijndael-cbc@lysator.liu.se",
84 SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
85 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr },
86 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr },
87 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr },
88 #ifdef USE_CIPHER_ACSS
89 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
91 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
97 cipher_blocksize(const Cipher *c)
99 return (c->block_size);
103 cipher_keylen(const Cipher *c)
109 cipher_get_number(const Cipher *c)
115 cipher_is_cbc(const Cipher *c)
117 return (c->cbc_mode);
121 cipher_mask_ssh1(int client)
124 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
125 mask |= 1 << SSH_CIPHER_BLOWFISH;
127 mask |= 1 << SSH_CIPHER_DES;
133 cipher_by_name(const char *name)
136 for (c = ciphers; c->name != NULL; c++)
137 if (strcmp(c->name, name) == 0)
143 cipher_by_number(int id)
146 for (c = ciphers; c->name != NULL; c++)
152 #define CIPHER_SEP ","
154 ciphers_valid(const char *names)
157 char *cipher_list, *cp;
160 if (names == NULL || strcmp(names, "") == 0)
162 cipher_list = cp = xstrdup(names);
163 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
164 (p = strsep(&cp, CIPHER_SEP))) {
165 c = cipher_by_name(p);
166 if (c == NULL || (c->number != SSH_CIPHER_SSH2 &&
167 c->number != SSH_CIPHER_NONE)) {
168 debug("bad cipher %s [%s]", p, names);
172 debug3("cipher ok: %s [%s]", p, names);
175 debug3("ciphers ok: [%s]", names);
181 * Parses the name of the cipher. Returns the number of the corresponding
182 * cipher, or -1 on error.
186 cipher_number(const char *name)
191 for (c = ciphers; c->name != NULL; c++)
192 if (strcasecmp(c->name, name) == 0)
200 Cipher *c = cipher_by_number(id);
201 return (c==NULL) ? "<unknown>" : c->name;
205 cipher_init(CipherContext *cc, Cipher *cipher,
206 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
209 static int dowarn = 1;
213 const EVP_CIPHER *type;
216 u_char *junk, *discard;
218 if (cipher->number == SSH_CIPHER_DES) {
220 error("Warning: use of DES is strongly discouraged "
221 "due to cryptographic weaknesses");
227 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
229 if (keylen < cipher->key_len)
230 fatal("cipher_init: key length %d is insufficient for %s.",
231 keylen, cipher->name);
232 if (iv != NULL && ivlen < cipher->block_size)
233 fatal("cipher_init: iv length %d is insufficient for %s.",
234 ivlen, cipher->name);
237 type = (*cipher->evptype)();
239 EVP_CIPHER_CTX_init(&cc->evp);
241 if (type->key_len > 0 && type->key_len != keylen) {
242 debug("cipher_init: set keylen (%d -> %d)",
243 type->key_len, keylen);
244 type->key_len = keylen;
246 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
247 (do_encrypt == CIPHER_ENCRYPT));
249 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
250 (do_encrypt == CIPHER_ENCRYPT)) == 0)
251 fatal("cipher_init: EVP_CipherInit failed for %s",
253 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
254 if (klen > 0 && keylen != (u_int)klen) {
255 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
256 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
257 fatal("cipher_init: set keylen failed (%d -> %d)",
260 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
261 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
265 if (cipher->discard_len > 0) {
266 junk = xmalloc(cipher->discard_len);
267 discard = xmalloc(cipher->discard_len);
268 if (EVP_Cipher(&cc->evp, discard, junk,
269 cipher->discard_len) == 0)
270 fatal("evp_crypt: EVP_Cipher failed during discard");
271 memset(discard, 0, cipher->discard_len);
278 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
280 if (len % cc->cipher->block_size)
281 fatal("cipher_encrypt: bad plaintext length %d", len);
282 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
283 fatal("evp_crypt: EVP_Cipher failed");
287 cipher_cleanup(CipherContext *cc)
289 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
290 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
294 * Selects the cipher, and keys if by computing the MD5 checksum of the
295 * passphrase and using the resulting 16 bytes as the key.
299 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
300 const char *passphrase, int do_encrypt)
306 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
307 MD5_Final(digest, &md);
309 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
311 memset(digest, 0, sizeof(digest));
312 memset(&md, 0, sizeof(md));
316 * Exports an IV from the CipherContext required to export the key
317 * state back from the unprivileged child to the privileged parent
322 cipher_get_keyiv_len(const CipherContext *cc)
324 Cipher *c = cc->cipher;
327 if (c->number == SSH_CIPHER_3DES)
330 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
335 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
337 Cipher *c = cc->cipher;
341 case SSH_CIPHER_NONE:
342 case SSH_CIPHER_SSH2:
344 case SSH_CIPHER_BLOWFISH:
345 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
348 if ((u_int)evplen != len)
349 fatal("%s: wrong iv length %d != %d", __func__,
351 #ifdef USE_BUILTIN_RIJNDAEL
352 if (c->evptype == evp_rijndael)
353 ssh_rijndael_iv(&cc->evp, 0, iv, len);
356 if (c->evptype == evp_aes_128_ctr)
357 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
359 memcpy(iv, cc->evp.iv, len);
361 case SSH_CIPHER_3DES:
362 ssh1_3des_iv(&cc->evp, 0, iv, 24);
365 fatal("%s: bad cipher %d", __func__, c->number);
370 cipher_set_keyiv(CipherContext *cc, u_char *iv)
372 Cipher *c = cc->cipher;
376 case SSH_CIPHER_NONE:
377 case SSH_CIPHER_SSH2:
379 case SSH_CIPHER_BLOWFISH:
380 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
383 #ifdef USE_BUILTIN_RIJNDAEL
384 if (c->evptype == evp_rijndael)
385 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
388 if (c->evptype == evp_aes_128_ctr)
389 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
391 memcpy(cc->evp.iv, iv, evplen);
393 case SSH_CIPHER_3DES:
394 ssh1_3des_iv(&cc->evp, 1, iv, 24);
397 fatal("%s: bad cipher %d", __func__, c->number);
401 #if OPENSSL_VERSION_NUMBER < 0x00907000L
402 #define EVP_X_STATE(evp) &(evp).c
403 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
405 #define EVP_X_STATE(evp) (evp).cipher_data
406 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
410 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
412 Cipher *c = cc->cipher;
415 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
416 plen = EVP_X_STATE_LEN(cc->evp);
419 memcpy(dat, EVP_X_STATE(cc->evp), plen);
425 cipher_set_keycontext(CipherContext *cc, u_char *dat)
427 Cipher *c = cc->cipher;
430 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
431 plen = EVP_X_STATE_LEN(cc->evp);
432 memcpy(EVP_X_STATE(cc->evp), dat, plen);