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3c0ef626 1/*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5 *
6 * As far as I am concerned, the code I have written for this software
7 * can be used freely for any purpose. Any derived versions of this
8 * software must be clearly marked as such, and if the derived work is
9 * incompatible with the protocol description in the RFC file, it must be
10 * called by a name other than "ssh" or "Secure Shell".
11 *
12 *
13 * Copyright (c) 1999 Niels Provos. All rights reserved.
14 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 */
36
37#include "includes.h"
dfddba3d 38RCSID("$OpenBSD: cipher.c,v 1.73 2005/01/23 10:18:12 djm Exp $");
3c0ef626 39
40#include "xmalloc.h"
41#include "log.h"
42#include "cipher.h"
43
44#include <openssl/md5.h>
905081a4 45
350391c5 46#if OPENSSL_VERSION_NUMBER < 0x00906000L
47#define SSH_OLD_EVP
48#define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
49#endif
50
44a053a3 51#if OPENSSL_VERSION_NUMBER < 0x00907000L
7cac2b65 52extern const EVP_CIPHER *evp_rijndael(void);
53extern void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
44a053a3 54#endif
540d72c3 55
56#if !defined(EVP_CTRL_SET_ACSS_MODE)
57# if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
58extern const EVP_CIPHER *evp_acss(void);
59# define EVP_acss evp_acss
60# define EVP_CTRL_SET_ACSS_MODE xxx /* used below */
61# else
62# define EVP_acss NULL /* Don't try to support ACSS on older OpenSSL */
63# endif /* (OPENSSL_VERSION_NUMBER >= 0x00906000L) */
64#endif /* !defined(EVP_CTRL_SET_ACSS_MODE) */
65
7cac2b65 66extern const EVP_CIPHER *evp_ssh1_bf(void);
67extern const EVP_CIPHER *evp_ssh1_3des(void);
68extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
69extern const EVP_CIPHER *evp_aes_128_ctr(void);
70extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
905081a4 71
72struct Cipher {
73 char *name;
74 int number; /* for ssh1 only */
75 u_int block_size;
76 u_int key_len;
44a053a3 77 const EVP_CIPHER *(*evptype)(void);
905081a4 78} ciphers[] = {
7e82606e 79 { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
80 { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
81 { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
82 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
83
84 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
85 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
86 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
87 { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
44a053a3 88#if OPENSSL_VERSION_NUMBER < 0x00907000L
7e82606e 89 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
90 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
91 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
350391c5 92 { "rijndael-cbc@lysator.liu.se",
93 SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
44a053a3 94#else
95 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc },
96 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc },
97 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
98 { "rijndael-cbc@lysator.liu.se",
99 SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
100#endif
540d72c3 101#if OPENSSL_VERSION_NUMBER >= 0x00905000L
7e82606e 102 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, evp_aes_128_ctr },
103 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, evp_aes_128_ctr },
104 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, evp_aes_128_ctr },
29d88157 105#endif
540d72c3 106#if defined(EVP_CTRL_SET_ACSS_MODE)
107 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, EVP_acss },
108#endif
7e82606e 109 { NULL, SSH_CIPHER_INVALID, 0, 0, NULL }
905081a4 110};
3c0ef626 111
905081a4 112/*--*/
3c0ef626 113
905081a4 114u_int
540d72c3 115cipher_blocksize(const Cipher *c)
3c0ef626 116{
905081a4 117 return (c->block_size);
3c0ef626 118}
276b07a3 119
905081a4 120u_int
540d72c3 121cipher_keylen(const Cipher *c)
3c0ef626 122{
905081a4 123 return (c->key_len);
3c0ef626 124}
276b07a3 125
905081a4 126u_int
540d72c3 127cipher_get_number(const Cipher *c)
3c0ef626 128{
905081a4 129 return (c->number);
3c0ef626 130}
131
3c0ef626 132u_int
133cipher_mask_ssh1(int client)
134{
135 u_int mask = 0;
905081a4 136 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
3c0ef626 137 mask |= 1 << SSH_CIPHER_BLOWFISH;
138 if (client) {
139 mask |= 1 << SSH_CIPHER_DES;
140 }
141 return mask;
142}
143
144Cipher *
145cipher_by_name(const char *name)
146{
147 Cipher *c;
148 for (c = ciphers; c->name != NULL; c++)
dfddba3d 149 if (strcmp(c->name, name) == 0)
3c0ef626 150 return c;
151 return NULL;
152}
153
154Cipher *
155cipher_by_number(int id)
156{
157 Cipher *c;
158 for (c = ciphers; c->name != NULL; c++)
159 if (c->number == id)
160 return c;
161 return NULL;
162}
163
164#define CIPHER_SEP ","
165int
166ciphers_valid(const char *names)
167{
168 Cipher *c;
7e82606e 169 char *cipher_list, *cp;
3c0ef626 170 char *p;
171
172 if (names == NULL || strcmp(names, "") == 0)
173 return 0;
7e82606e 174 cipher_list = cp = xstrdup(names);
3c0ef626 175 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
905081a4 176 (p = strsep(&cp, CIPHER_SEP))) {
3c0ef626 177 c = cipher_by_name(p);
178 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
179 debug("bad cipher %s [%s]", p, names);
7e82606e 180 xfree(cipher_list);
3c0ef626 181 return 0;
182 } else {
183 debug3("cipher ok: %s [%s]", p, names);
184 }
185 }
186 debug3("ciphers ok: [%s]", names);
7e82606e 187 xfree(cipher_list);
3c0ef626 188 return 1;
189}
190
191/*
192 * Parses the name of the cipher. Returns the number of the corresponding
193 * cipher, or -1 on error.
194 */
195
196int
197cipher_number(const char *name)
198{
199 Cipher *c;
200 if (name == NULL)
201 return -1;
dfddba3d 202 for (c = ciphers; c->name != NULL; c++)
203 if (strcasecmp(c->name, name) == 0)
204 return c->number;
205 return -1;
3c0ef626 206}
207
208char *
209cipher_name(int id)
210{
211 Cipher *c = cipher_by_number(id);
212 return (c==NULL) ? "<unknown>" : c->name;
213}
214
215void
216cipher_init(CipherContext *cc, Cipher *cipher,
905081a4 217 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
7e82606e 218 int do_encrypt)
3c0ef626 219{
905081a4 220 static int dowarn = 1;
350391c5 221#ifdef SSH_OLD_EVP
222 EVP_CIPHER *type;
223#else
905081a4 224 const EVP_CIPHER *type;
350391c5 225#endif
905081a4 226 int klen;
227
228 if (cipher->number == SSH_CIPHER_DES) {
229 if (dowarn) {
230 error("Warning: use of DES is strongly discouraged "
231 "due to cryptographic weaknesses");
232 dowarn = 0;
233 }
234 if (keylen > 8)
235 keylen = 8;
236 }
237 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
238
3c0ef626 239 if (keylen < cipher->key_len)
240 fatal("cipher_init: key length %d is insufficient for %s.",
241 keylen, cipher->name);
242 if (iv != NULL && ivlen < cipher->block_size)
243 fatal("cipher_init: iv length %d is insufficient for %s.",
244 ivlen, cipher->name);
245 cc->cipher = cipher;
905081a4 246
247 type = (*cipher->evptype)();
248
249 EVP_CIPHER_CTX_init(&cc->evp);
350391c5 250#ifdef SSH_OLD_EVP
251 if (type->key_len > 0 && type->key_len != keylen) {
252 debug("cipher_init: set keylen (%d -> %d)",
253 type->key_len, keylen);
254 type->key_len = keylen;
255 }
256 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
7e82606e 257 (do_encrypt == CIPHER_ENCRYPT));
350391c5 258#else
905081a4 259 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
7e82606e 260 (do_encrypt == CIPHER_ENCRYPT)) == 0)
905081a4 261 fatal("cipher_init: EVP_CipherInit failed for %s",
262 cipher->name);
263 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
264 if (klen > 0 && keylen != klen) {
bfe49944 265 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
905081a4 266 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
267 fatal("cipher_init: set keylen failed (%d -> %d)",
268 klen, keylen);
269 }
270 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
271 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
272 cipher->name);
350391c5 273#endif
3c0ef626 274}
275
276void
905081a4 277cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
3c0ef626 278{
279 if (len % cc->cipher->block_size)
280 fatal("cipher_encrypt: bad plaintext length %d", len);
350391c5 281#ifdef SSH_OLD_EVP
282 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
283#else
905081a4 284 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
285 fatal("evp_crypt: EVP_Cipher failed");
350391c5 286#endif
3c0ef626 287}
288
289void
905081a4 290cipher_cleanup(CipherContext *cc)
3c0ef626 291{
350391c5 292#ifdef SSH_OLD_EVP
293 EVP_CIPHER_CTX_cleanup(&cc->evp);
294#else
905081a4 295 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
296 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
350391c5 297#endif
3c0ef626 298}
299
300/*
301 * Selects the cipher, and keys if by computing the MD5 checksum of the
302 * passphrase and using the resulting 16 bytes as the key.
303 */
304
305void
306cipher_set_key_string(CipherContext *cc, Cipher *cipher,
7e82606e 307 const char *passphrase, int do_encrypt)
3c0ef626 308{
309 MD5_CTX md;
310 u_char digest[16];
311
312 MD5_Init(&md);
313 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
314 MD5_Final(digest, &md);
315
7e82606e 316 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
3c0ef626 317
318 memset(digest, 0, sizeof(digest));
319 memset(&md, 0, sizeof(md));
320}
905081a4 321
905081a4 322/*
323 * Exports an IV from the CipherContext required to export the key
324 * state back from the unprivileged child to the privileged parent
325 * process.
326 */
327
328int
540d72c3 329cipher_get_keyiv_len(const CipherContext *cc)
905081a4 330{
331 Cipher *c = cc->cipher;
332 int ivlen;
333
334 if (c->number == SSH_CIPHER_3DES)
335 ivlen = 24;
336 else
337 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
338 return (ivlen);
339}
340
341void
342cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
343{
344 Cipher *c = cc->cipher;
905081a4 345 int evplen;
346
347 switch (c->number) {
348 case SSH_CIPHER_SSH2:
349 case SSH_CIPHER_DES:
350 case SSH_CIPHER_BLOWFISH:
351 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
352 if (evplen == 0)
353 return;
354 if (evplen != len)
44a053a3 355 fatal("%s: wrong iv length %d != %d", __func__,
905081a4 356 evplen, len);
44a053a3 357#if OPENSSL_VERSION_NUMBER < 0x00907000L
7cac2b65 358 if (c->evptype == evp_rijndael)
359 ssh_rijndael_iv(&cc->evp, 0, iv, len);
360 else
44a053a3 361#endif
7cac2b65 362 if (c->evptype == evp_aes_128_ctr)
363 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
364 else
365 memcpy(iv, cc->evp.iv, len);
366 break;
367 case SSH_CIPHER_3DES:
368 ssh1_3des_iv(&cc->evp, 0, iv, 24);
905081a4 369 break;
905081a4 370 default:
44a053a3 371 fatal("%s: bad cipher %d", __func__, c->number);
905081a4 372 }
905081a4 373}
374
375void
376cipher_set_keyiv(CipherContext *cc, u_char *iv)
377{
378 Cipher *c = cc->cipher;
905081a4 379 int evplen = 0;
380
381 switch (c->number) {
382 case SSH_CIPHER_SSH2:
383 case SSH_CIPHER_DES:
384 case SSH_CIPHER_BLOWFISH:
385 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
386 if (evplen == 0)
387 return;
44a053a3 388#if OPENSSL_VERSION_NUMBER < 0x00907000L
7cac2b65 389 if (c->evptype == evp_rijndael)
390 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
391 else
44a053a3 392#endif
7cac2b65 393 if (c->evptype == evp_aes_128_ctr)
394 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
395 else
396 memcpy(cc->evp.iv, iv, evplen);
397 break;
398 case SSH_CIPHER_3DES:
399 ssh1_3des_iv(&cc->evp, 1, iv, 24);
905081a4 400 break;
905081a4 401 default:
44a053a3 402 fatal("%s: bad cipher %d", __func__, c->number);
905081a4 403 }
905081a4 404}
405
406#if OPENSSL_VERSION_NUMBER < 0x00907000L
407#define EVP_X_STATE(evp) &(evp).c
408#define EVP_X_STATE_LEN(evp) sizeof((evp).c)
409#else
410#define EVP_X_STATE(evp) (evp).cipher_data
411#define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
412#endif
413
414int
540d72c3 415cipher_get_keycontext(const CipherContext *cc, u_char *dat)
905081a4 416{
417 Cipher *c = cc->cipher;
44a053a3 418 int plen = 0;
905081a4 419
540d72c3 420 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
44a053a3 421 plen = EVP_X_STATE_LEN(cc->evp);
905081a4 422 if (dat == NULL)
44a053a3 423 return (plen);
424 memcpy(dat, EVP_X_STATE(cc->evp), plen);
905081a4 425 }
905081a4 426 return (plen);
427}
428
429void
430cipher_set_keycontext(CipherContext *cc, u_char *dat)
431{
432 Cipher *c = cc->cipher;
433 int plen;
434
540d72c3 435 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
905081a4 436 plen = EVP_X_STATE_LEN(cc->evp);
437 memcpy(EVP_X_STATE(cc->evp), dat, plen);
438 }
439}
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