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00146caa | 1 | /* $OpenBSD: cipher.c,v 1.80 2006/07/22 20:48:22 stevesk Exp $ */ |
8efc0c15 | 2 | /* |
5260325f | 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
5 | * All rights reserved | |
6ae2364d | 6 | * |
bcbf86ec | 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". | |
12 | * | |
13 | * | |
14 | * Copyright (c) 1999 Niels Provos. All rights reserved. | |
a96070d4 | 15 | * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. |
bcbf86ec | 16 | * |
17 | * Redistribution and use in source and binary forms, with or without | |
18 | * modification, are permitted provided that the following conditions | |
19 | * are met: | |
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. | |
6ae2364d | 25 | * |
bcbf86ec | 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. | |
5260325f | 36 | */ |
8efc0c15 | 37 | |
38 | #include "includes.h" | |
8efc0c15 | 39 | |
00146caa | 40 | #include <openssl/md5.h> |
41 | ||
42 | #include <string.h> | |
43 | ||
a8be9f80 | 44 | #include "xmalloc.h" |
42f11eb2 | 45 | #include "log.h" |
46 | #include "cipher.h" | |
8efc0c15 | 47 | |
601b831d | 48 | /* compatibility with old or broken OpenSSL versions */ |
49 | #include "openbsd-compat/openssl-compat.h" | |
50 | ||
3b6e3da9 | 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); | |
25b66522 | 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); | |
8efc0c15 | 56 | |
3ee832e5 | 57 | struct Cipher { |
58 | char *name; | |
59 | int number; /* for ssh1 only */ | |
60 | u_int block_size; | |
61 | u_int key_len; | |
74a66cc8 | 62 | u_int discard_len; |
7b5edc2b | 63 | const EVP_CIPHER *(*evptype)(void); |
70fc1609 | 64 | } ciphers[] = { |
74a66cc8 | 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 }, | |
70fc1609 | 69 | |
74a66cc8 | 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 }, | |
74a66cc8 | 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 }, | |
135247df | 79 | { "rijndael-cbc@lysator.liu.se", |
74a66cc8 | 80 | SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, |
74a66cc8 | 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 }, | |
52607c0f | 84 | #ifdef USE_CIPHER_ACSS |
74a66cc8 | 85 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss }, |
268c23e9 | 86 | #endif |
74a66cc8 | 87 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL } |
94ec8c6b | 88 | }; |
89 | ||
90 | /*--*/ | |
91 | ||
762715ce | 92 | u_int |
b6c7b7b7 | 93 | cipher_blocksize(const Cipher *c) |
3ee832e5 | 94 | { |
95 | return (c->block_size); | |
96 | } | |
3ddc795d | 97 | |
762715ce | 98 | u_int |
b6c7b7b7 | 99 | cipher_keylen(const Cipher *c) |
3ee832e5 | 100 | { |
101 | return (c->key_len); | |
102 | } | |
3ddc795d | 103 | |
762715ce | 104 | u_int |
b6c7b7b7 | 105 | cipher_get_number(const Cipher *c) |
bf8269a9 | 106 | { |
107 | return (c->number); | |
108 | } | |
3ee832e5 | 109 | |
1e3b8b07 | 110 | u_int |
94ec8c6b | 111 | cipher_mask_ssh1(int client) |
8ce64345 | 112 | { |
1e3b8b07 | 113 | u_int mask = 0; |
184eed6a | 114 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
94ec8c6b | 115 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
116 | if (client) { | |
117 | mask |= 1 << SSH_CIPHER_DES; | |
118 | } | |
5260325f | 119 | return mask; |
8efc0c15 | 120 | } |
94ec8c6b | 121 | |
122 | Cipher * | |
123 | cipher_by_name(const char *name) | |
8ce64345 | 124 | { |
94ec8c6b | 125 | Cipher *c; |
126 | for (c = ciphers; c->name != NULL; c++) | |
3ebbcf03 | 127 | if (strcmp(c->name, name) == 0) |
94ec8c6b | 128 | return c; |
129 | return NULL; | |
8ce64345 | 130 | } |
8efc0c15 | 131 | |
94ec8c6b | 132 | Cipher * |
133 | cipher_by_number(int id) | |
8efc0c15 | 134 | { |
94ec8c6b | 135 | Cipher *c; |
136 | for (c = ciphers; c->name != NULL; c++) | |
137 | if (c->number == id) | |
138 | return c; | |
139 | return NULL; | |
8efc0c15 | 140 | } |
141 | ||
a8be9f80 | 142 | #define CIPHER_SEP "," |
143 | int | |
144 | ciphers_valid(const char *names) | |
145 | { | |
94ec8c6b | 146 | Cipher *c; |
ca75d7de | 147 | char *cipher_list, *cp; |
a8be9f80 | 148 | char *p; |
a8be9f80 | 149 | |
71276795 | 150 | if (names == NULL || strcmp(names, "") == 0) |
a8be9f80 | 151 | return 0; |
ca75d7de | 152 | cipher_list = cp = xstrdup(names); |
94ec8c6b | 153 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
184eed6a | 154 | (p = strsep(&cp, CIPHER_SEP))) { |
94ec8c6b | 155 | c = cipher_by_name(p); |
156 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
157 | debug("bad cipher %s [%s]", p, names); | |
ca75d7de | 158 | xfree(cipher_list); |
a8be9f80 | 159 | return 0; |
94ec8c6b | 160 | } else { |
33de75a3 | 161 | debug3("cipher ok: %s [%s]", p, names); |
a8be9f80 | 162 | } |
163 | } | |
33de75a3 | 164 | debug3("ciphers ok: [%s]", names); |
ca75d7de | 165 | xfree(cipher_list); |
a8be9f80 | 166 | return 1; |
167 | } | |
168 | ||
aa3378df | 169 | /* |
170 | * Parses the name of the cipher. Returns the number of the corresponding | |
171 | * cipher, or -1 on error. | |
172 | */ | |
8efc0c15 | 173 | |
174 | int | |
175 | cipher_number(const char *name) | |
176 | { | |
94ec8c6b | 177 | Cipher *c; |
71276795 | 178 | if (name == NULL) |
179 | return -1; | |
3ebbcf03 | 180 | for (c = ciphers; c->name != NULL; c++) |
181 | if (strcasecmp(c->name, name) == 0) | |
182 | return c->number; | |
183 | return -1; | |
94ec8c6b | 184 | } |
185 | ||
186 | char * | |
187 | cipher_name(int id) | |
188 | { | |
189 | Cipher *c = cipher_by_number(id); | |
190 | return (c==NULL) ? "<unknown>" : c->name; | |
191 | } | |
192 | ||
193 | void | |
70fc1609 | 194 | cipher_init(CipherContext *cc, Cipher *cipher, |
195 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, | |
ca75d7de | 196 | int do_encrypt) |
94ec8c6b | 197 | { |
70fc1609 | 198 | static int dowarn = 1; |
a068d86f | 199 | #ifdef SSH_OLD_EVP |
200 | EVP_CIPHER *type; | |
201 | #else | |
70fc1609 | 202 | const EVP_CIPHER *type; |
203 | int klen; | |
52607c0f | 204 | #endif |
74a66cc8 | 205 | u_char *junk, *discard; |
70fc1609 | 206 | |
207 | if (cipher->number == SSH_CIPHER_DES) { | |
208 | if (dowarn) { | |
209 | error("Warning: use of DES is strongly discouraged " | |
210 | "due to cryptographic weaknesses"); | |
211 | dowarn = 0; | |
212 | } | |
213 | if (keylen > 8) | |
214 | keylen = 8; | |
215 | } | |
216 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
217 | ||
94ec8c6b | 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); | |
224 | cc->cipher = cipher; | |
70fc1609 | 225 | |
226 | type = (*cipher->evptype)(); | |
227 | ||
228 | EVP_CIPHER_CTX_init(&cc->evp); | |
a068d86f | 229 | #ifdef SSH_OLD_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; | |
234 | } | |
235 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
9ea217e8 | 236 | (do_encrypt == CIPHER_ENCRYPT)); |
a068d86f | 237 | #else |
70fc1609 | 238 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
ca75d7de | 239 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
70fc1609 | 240 | fatal("cipher_init: EVP_CipherInit failed for %s", |
241 | cipher->name); | |
242 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
2ceb8101 | 243 | if (klen > 0 && keylen != (u_int)klen) { |
a77673cc | 244 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
70fc1609 | 245 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
246 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
247 | klen, keylen); | |
248 | } | |
249 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
250 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
251 | cipher->name); | |
a068d86f | 252 | #endif |
74a66cc8 | 253 | |
56964485 | 254 | if (cipher->discard_len > 0) { |
74a66cc8 | 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); | |
261 | xfree(junk); | |
262 | xfree(discard); | |
263 | } | |
94ec8c6b | 264 | } |
265 | ||
266 | void | |
3ee832e5 | 267 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
94ec8c6b | 268 | { |
269 | if (len % cc->cipher->block_size) | |
270 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
70fc1609 | 271 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
272 | fatal("evp_crypt: EVP_Cipher failed"); | |
94ec8c6b | 273 | } |
274 | ||
275 | void | |
3ee832e5 | 276 | cipher_cleanup(CipherContext *cc) |
94ec8c6b | 277 | { |
70fc1609 | 278 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
279 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
8efc0c15 | 280 | } |
281 | ||
aa3378df | 282 | /* |
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. | |
285 | */ | |
8efc0c15 | 286 | |
6ae2364d | 287 | void |
94ec8c6b | 288 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, |
ca75d7de | 289 | const char *passphrase, int do_encrypt) |
8efc0c15 | 290 | { |
5260325f | 291 | MD5_CTX md; |
1e3b8b07 | 292 | u_char digest[16]; |
5260325f | 293 | |
294 | MD5_Init(&md); | |
94ec8c6b | 295 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); |
5260325f | 296 | MD5_Final(digest, &md); |
297 | ||
ca75d7de | 298 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
5260325f | 299 | |
300 | memset(digest, 0, sizeof(digest)); | |
301 | memset(&md, 0, sizeof(md)); | |
8efc0c15 | 302 | } |
70fc1609 | 303 | |
762715ce | 304 | /* |
bf8269a9 | 305 | * Exports an IV from the CipherContext required to export the key |
306 | * state back from the unprivileged child to the privileged parent | |
307 | * process. | |
308 | */ | |
309 | ||
310 | int | |
b6c7b7b7 | 311 | cipher_get_keyiv_len(const CipherContext *cc) |
bf8269a9 | 312 | { |
313 | Cipher *c = cc->cipher; | |
314 | int ivlen; | |
315 | ||
316 | if (c->number == SSH_CIPHER_3DES) | |
317 | ivlen = 24; | |
318 | else | |
319 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
320 | return (ivlen); | |
321 | } | |
322 | ||
323 | void | |
324 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
325 | { | |
326 | Cipher *c = cc->cipher; | |
bf8269a9 | 327 | int evplen; |
328 | ||
329 | switch (c->number) { | |
330 | case SSH_CIPHER_SSH2: | |
331 | case SSH_CIPHER_DES: | |
332 | case SSH_CIPHER_BLOWFISH: | |
333 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
2ceb8101 | 334 | if (evplen <= 0) |
bf8269a9 | 335 | return; |
2ceb8101 | 336 | if ((u_int)evplen != len) |
1588c277 | 337 | fatal("%s: wrong iv length %d != %d", __func__, |
bf8269a9 | 338 | evplen, len); |
e5146707 | 339 | #ifdef USE_BUILTIN_RIJNDAEL |
18ae3c67 | 340 | if (c->evptype == evp_rijndael) |
341 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
342 | else | |
135247df | 343 | #endif |
25b66522 | 344 | if (c->evptype == evp_aes_128_ctr) |
345 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
346 | else | |
18ae3c67 | 347 | memcpy(iv, cc->evp.iv, len); |
348 | break; | |
349 | case SSH_CIPHER_3DES: | |
350 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
bf8269a9 | 351 | break; |
bf8269a9 | 352 | default: |
1588c277 | 353 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 354 | } |
bf8269a9 | 355 | } |
356 | ||
357 | void | |
358 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
359 | { | |
360 | Cipher *c = cc->cipher; | |
bf8269a9 | 361 | int evplen = 0; |
362 | ||
363 | switch (c->number) { | |
364 | case SSH_CIPHER_SSH2: | |
365 | case SSH_CIPHER_DES: | |
366 | case SSH_CIPHER_BLOWFISH: | |
367 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
368 | if (evplen == 0) | |
369 | return; | |
e5146707 | 370 | #ifdef USE_BUILTIN_RIJNDAEL |
18ae3c67 | 371 | if (c->evptype == evp_rijndael) |
372 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
373 | else | |
135247df | 374 | #endif |
25b66522 | 375 | if (c->evptype == evp_aes_128_ctr) |
376 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
377 | else | |
18ae3c67 | 378 | memcpy(cc->evp.iv, iv, evplen); |
379 | break; | |
380 | case SSH_CIPHER_3DES: | |
381 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
bf8269a9 | 382 | break; |
bf8269a9 | 383 | default: |
1588c277 | 384 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 385 | } |
bf8269a9 | 386 | } |
387 | ||
388 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
389 | #define EVP_X_STATE(evp) &(evp).c | |
390 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
391 | #else | |
392 | #define EVP_X_STATE(evp) (evp).cipher_data | |
393 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
394 | #endif | |
395 | ||
396 | int | |
b6c7b7b7 | 397 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
bf8269a9 | 398 | { |
399 | Cipher *c = cc->cipher; | |
9459414c | 400 | int plen = 0; |
bf8269a9 | 401 | |
268c23e9 | 402 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
9459414c | 403 | plen = EVP_X_STATE_LEN(cc->evp); |
bf8269a9 | 404 | if (dat == NULL) |
9459414c | 405 | return (plen); |
406 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
bf8269a9 | 407 | } |
bf8269a9 | 408 | return (plen); |
409 | } | |
410 | ||
411 | void | |
412 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
413 | { | |
414 | Cipher *c = cc->cipher; | |
415 | int plen; | |
416 | ||
268c23e9 | 417 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
bf8269a9 | 418 | plen = EVP_X_STATE_LEN(cc->evp); |
419 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
420 | } | |
70fc1609 | 421 | } |