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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
6ae2364d | 5 | * |
bcbf86ec | 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. | |
a96070d4 | 14 | * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. |
bcbf86ec | 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. | |
6ae2364d | 24 | * |
bcbf86ec | 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. | |
5260325f | 35 | */ |
8efc0c15 | 36 | |
37 | #include "includes.h" | |
25b66522 | 38 | RCSID("$OpenBSD: cipher.c,v 1.65 2003/05/17 04:27:52 markus Exp $"); |
8efc0c15 | 39 | |
a8be9f80 | 40 | #include "xmalloc.h" |
42f11eb2 | 41 | #include "log.h" |
42 | #include "cipher.h" | |
8efc0c15 | 43 | |
44 | #include <openssl/md5.h> | |
70fc1609 | 45 | |
a068d86f | 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 | ||
135247df | 51 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
3b6e3da9 | 52 | extern const EVP_CIPHER *evp_rijndael(void); |
53 | extern void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
135247df | 54 | #endif |
3b6e3da9 | 55 | extern const EVP_CIPHER *evp_ssh1_bf(void); |
56 | extern const EVP_CIPHER *evp_ssh1_3des(void); | |
57 | extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); | |
25b66522 | 58 | extern const EVP_CIPHER *evp_aes_128_ctr(void); |
59 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
8efc0c15 | 60 | |
3ee832e5 | 61 | struct Cipher { |
62 | char *name; | |
63 | int number; /* for ssh1 only */ | |
64 | u_int block_size; | |
65 | u_int key_len; | |
7b5edc2b | 66 | const EVP_CIPHER *(*evptype)(void); |
70fc1609 | 67 | } ciphers[] = { |
68 | { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null }, | |
69 | { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc }, | |
70 | { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des }, | |
71 | { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf }, | |
72 | ||
73 | { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc }, | |
74 | { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc }, | |
75 | { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc }, | |
76 | { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 }, | |
135247df | 77 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
70fc1609 | 78 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael }, |
79 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael }, | |
80 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael }, | |
bf03f2da | 81 | { "rijndael-cbc@lysator.liu.se", |
82 | SSH_CIPHER_SSH2, 16, 32, evp_rijndael }, | |
135247df | 83 | #else |
84 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc }, | |
85 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc }, | |
86 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc }, | |
87 | { "rijndael-cbc@lysator.liu.se", | |
88 | SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc }, | |
89 | #endif | |
25b66522 | 90 | { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, evp_aes_128_ctr }, |
91 | { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, evp_aes_128_ctr }, | |
92 | { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, evp_aes_128_ctr }, | |
70fc1609 | 93 | |
94 | { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL } | |
94ec8c6b | 95 | }; |
96 | ||
97 | /*--*/ | |
98 | ||
762715ce | 99 | u_int |
3ee832e5 | 100 | cipher_blocksize(Cipher *c) |
101 | { | |
102 | return (c->block_size); | |
103 | } | |
3ddc795d | 104 | |
762715ce | 105 | u_int |
3ee832e5 | 106 | cipher_keylen(Cipher *c) |
107 | { | |
108 | return (c->key_len); | |
109 | } | |
3ddc795d | 110 | |
762715ce | 111 | u_int |
bf8269a9 | 112 | cipher_get_number(Cipher *c) |
113 | { | |
114 | return (c->number); | |
115 | } | |
3ee832e5 | 116 | |
1e3b8b07 | 117 | u_int |
94ec8c6b | 118 | cipher_mask_ssh1(int client) |
8ce64345 | 119 | { |
1e3b8b07 | 120 | u_int mask = 0; |
184eed6a | 121 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
94ec8c6b | 122 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
123 | if (client) { | |
124 | mask |= 1 << SSH_CIPHER_DES; | |
125 | } | |
5260325f | 126 | return mask; |
8efc0c15 | 127 | } |
94ec8c6b | 128 | |
129 | Cipher * | |
130 | cipher_by_name(const char *name) | |
8ce64345 | 131 | { |
94ec8c6b | 132 | Cipher *c; |
133 | for (c = ciphers; c->name != NULL; c++) | |
134 | if (strcasecmp(c->name, name) == 0) | |
135 | return c; | |
136 | return NULL; | |
8ce64345 | 137 | } |
8efc0c15 | 138 | |
94ec8c6b | 139 | Cipher * |
140 | cipher_by_number(int id) | |
8efc0c15 | 141 | { |
94ec8c6b | 142 | Cipher *c; |
143 | for (c = ciphers; c->name != NULL; c++) | |
144 | if (c->number == id) | |
145 | return c; | |
146 | return NULL; | |
8efc0c15 | 147 | } |
148 | ||
a8be9f80 | 149 | #define CIPHER_SEP "," |
150 | int | |
151 | ciphers_valid(const char *names) | |
152 | { | |
94ec8c6b | 153 | Cipher *c; |
089fbbd2 | 154 | char *ciphers, *cp; |
a8be9f80 | 155 | char *p; |
a8be9f80 | 156 | |
71276795 | 157 | if (names == NULL || strcmp(names, "") == 0) |
a8be9f80 | 158 | return 0; |
089fbbd2 | 159 | ciphers = cp = xstrdup(names); |
94ec8c6b | 160 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
184eed6a | 161 | (p = strsep(&cp, CIPHER_SEP))) { |
94ec8c6b | 162 | c = cipher_by_name(p); |
163 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
164 | debug("bad cipher %s [%s]", p, names); | |
a8be9f80 | 165 | xfree(ciphers); |
166 | return 0; | |
94ec8c6b | 167 | } else { |
33de75a3 | 168 | debug3("cipher ok: %s [%s]", p, names); |
a8be9f80 | 169 | } |
170 | } | |
33de75a3 | 171 | debug3("ciphers ok: [%s]", names); |
a8be9f80 | 172 | xfree(ciphers); |
173 | return 1; | |
174 | } | |
175 | ||
aa3378df | 176 | /* |
177 | * Parses the name of the cipher. Returns the number of the corresponding | |
178 | * cipher, or -1 on error. | |
179 | */ | |
8efc0c15 | 180 | |
181 | int | |
182 | cipher_number(const char *name) | |
183 | { | |
94ec8c6b | 184 | Cipher *c; |
71276795 | 185 | if (name == NULL) |
186 | return -1; | |
94ec8c6b | 187 | c = cipher_by_name(name); |
188 | return (c==NULL) ? -1 : c->number; | |
189 | } | |
190 | ||
191 | char * | |
192 | cipher_name(int id) | |
193 | { | |
194 | Cipher *c = cipher_by_number(id); | |
195 | return (c==NULL) ? "<unknown>" : c->name; | |
196 | } | |
197 | ||
198 | void | |
70fc1609 | 199 | cipher_init(CipherContext *cc, Cipher *cipher, |
200 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, | |
201 | int encrypt) | |
94ec8c6b | 202 | { |
70fc1609 | 203 | static int dowarn = 1; |
a068d86f | 204 | #ifdef SSH_OLD_EVP |
205 | EVP_CIPHER *type; | |
206 | #else | |
70fc1609 | 207 | const EVP_CIPHER *type; |
a068d86f | 208 | #endif |
70fc1609 | 209 | int klen; |
210 | ||
211 | if (cipher->number == SSH_CIPHER_DES) { | |
212 | if (dowarn) { | |
213 | error("Warning: use of DES is strongly discouraged " | |
214 | "due to cryptographic weaknesses"); | |
215 | dowarn = 0; | |
216 | } | |
217 | if (keylen > 8) | |
218 | keylen = 8; | |
219 | } | |
220 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
221 | ||
94ec8c6b | 222 | if (keylen < cipher->key_len) |
223 | fatal("cipher_init: key length %d is insufficient for %s.", | |
224 | keylen, cipher->name); | |
225 | if (iv != NULL && ivlen < cipher->block_size) | |
226 | fatal("cipher_init: iv length %d is insufficient for %s.", | |
227 | ivlen, cipher->name); | |
228 | cc->cipher = cipher; | |
70fc1609 | 229 | |
230 | type = (*cipher->evptype)(); | |
231 | ||
232 | EVP_CIPHER_CTX_init(&cc->evp); | |
a068d86f | 233 | #ifdef SSH_OLD_EVP |
234 | if (type->key_len > 0 && type->key_len != keylen) { | |
235 | debug("cipher_init: set keylen (%d -> %d)", | |
236 | type->key_len, keylen); | |
237 | type->key_len = keylen; | |
238 | } | |
239 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
240 | (encrypt == CIPHER_ENCRYPT)); | |
241 | #else | |
70fc1609 | 242 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
243 | (encrypt == CIPHER_ENCRYPT)) == 0) | |
244 | fatal("cipher_init: EVP_CipherInit failed for %s", | |
245 | cipher->name); | |
246 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
247 | if (klen > 0 && keylen != klen) { | |
a77673cc | 248 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
70fc1609 | 249 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
250 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
251 | klen, keylen); | |
252 | } | |
253 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
254 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
255 | cipher->name); | |
a068d86f | 256 | #endif |
94ec8c6b | 257 | } |
258 | ||
259 | void | |
3ee832e5 | 260 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
94ec8c6b | 261 | { |
262 | if (len % cc->cipher->block_size) | |
263 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
a068d86f | 264 | #ifdef SSH_OLD_EVP |
265 | EVP_Cipher(&cc->evp, dest, (u_char *)src, len); | |
266 | #else | |
70fc1609 | 267 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
268 | fatal("evp_crypt: EVP_Cipher failed"); | |
a068d86f | 269 | #endif |
94ec8c6b | 270 | } |
271 | ||
272 | void | |
3ee832e5 | 273 | cipher_cleanup(CipherContext *cc) |
94ec8c6b | 274 | { |
a068d86f | 275 | #ifdef SSH_OLD_EVP |
276 | EVP_CIPHER_CTX_cleanup(&cc->evp); | |
277 | #else | |
70fc1609 | 278 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
279 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
a068d86f | 280 | #endif |
8efc0c15 | 281 | } |
282 | ||
aa3378df | 283 | /* |
284 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
285 | * passphrase and using the resulting 16 bytes as the key. | |
286 | */ | |
8efc0c15 | 287 | |
6ae2364d | 288 | void |
94ec8c6b | 289 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, |
3ee832e5 | 290 | const char *passphrase, int encrypt) |
8efc0c15 | 291 | { |
5260325f | 292 | MD5_CTX md; |
1e3b8b07 | 293 | u_char digest[16]; |
5260325f | 294 | |
295 | MD5_Init(&md); | |
94ec8c6b | 296 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); |
5260325f | 297 | MD5_Final(digest, &md); |
298 | ||
3ee832e5 | 299 | cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt); |
5260325f | 300 | |
301 | memset(digest, 0, sizeof(digest)); | |
302 | memset(&md, 0, sizeof(md)); | |
8efc0c15 | 303 | } |
70fc1609 | 304 | |
762715ce | 305 | /* |
bf8269a9 | 306 | * Exports an IV from the CipherContext required to export the key |
307 | * state back from the unprivileged child to the privileged parent | |
308 | * process. | |
309 | */ | |
310 | ||
311 | int | |
312 | cipher_get_keyiv_len(CipherContext *cc) | |
313 | { | |
314 | Cipher *c = cc->cipher; | |
315 | int ivlen; | |
316 | ||
317 | if (c->number == SSH_CIPHER_3DES) | |
318 | ivlen = 24; | |
319 | else | |
320 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
321 | return (ivlen); | |
322 | } | |
323 | ||
324 | void | |
325 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
326 | { | |
327 | Cipher *c = cc->cipher; | |
bf8269a9 | 328 | int evplen; |
329 | ||
330 | switch (c->number) { | |
331 | case SSH_CIPHER_SSH2: | |
332 | case SSH_CIPHER_DES: | |
333 | case SSH_CIPHER_BLOWFISH: | |
334 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
335 | if (evplen == 0) | |
336 | return; | |
337 | if (evplen != len) | |
1588c277 | 338 | fatal("%s: wrong iv length %d != %d", __func__, |
bf8269a9 | 339 | evplen, len); |
135247df | 340 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
18ae3c67 | 341 | if (c->evptype == evp_rijndael) |
342 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
343 | else | |
135247df | 344 | #endif |
25b66522 | 345 | if (c->evptype == evp_aes_128_ctr) |
346 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
347 | else | |
18ae3c67 | 348 | memcpy(iv, cc->evp.iv, len); |
349 | break; | |
350 | case SSH_CIPHER_3DES: | |
351 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
bf8269a9 | 352 | break; |
bf8269a9 | 353 | default: |
1588c277 | 354 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 355 | } |
bf8269a9 | 356 | } |
357 | ||
358 | void | |
359 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
360 | { | |
361 | Cipher *c = cc->cipher; | |
bf8269a9 | 362 | int evplen = 0; |
363 | ||
364 | switch (c->number) { | |
365 | case SSH_CIPHER_SSH2: | |
366 | case SSH_CIPHER_DES: | |
367 | case SSH_CIPHER_BLOWFISH: | |
368 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
369 | if (evplen == 0) | |
370 | return; | |
135247df | 371 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
18ae3c67 | 372 | if (c->evptype == evp_rijndael) |
373 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
374 | else | |
135247df | 375 | #endif |
25b66522 | 376 | if (c->evptype == evp_aes_128_ctr) |
377 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
378 | else | |
18ae3c67 | 379 | memcpy(cc->evp.iv, iv, evplen); |
380 | break; | |
381 | case SSH_CIPHER_3DES: | |
382 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
bf8269a9 | 383 | break; |
bf8269a9 | 384 | default: |
1588c277 | 385 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 386 | } |
bf8269a9 | 387 | } |
388 | ||
389 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
390 | #define EVP_X_STATE(evp) &(evp).c | |
391 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
392 | #else | |
393 | #define EVP_X_STATE(evp) (evp).cipher_data | |
394 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
395 | #endif | |
396 | ||
397 | int | |
398 | cipher_get_keycontext(CipherContext *cc, u_char *dat) | |
399 | { | |
400 | Cipher *c = cc->cipher; | |
9459414c | 401 | int plen = 0; |
bf8269a9 | 402 | |
9459414c | 403 | if (c->evptype == EVP_rc4) { |
404 | plen = EVP_X_STATE_LEN(cc->evp); | |
bf8269a9 | 405 | if (dat == NULL) |
9459414c | 406 | return (plen); |
407 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
bf8269a9 | 408 | } |
bf8269a9 | 409 | return (plen); |
410 | } | |
411 | ||
412 | void | |
413 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
414 | { | |
415 | Cipher *c = cc->cipher; | |
416 | int plen; | |
417 | ||
9459414c | 418 | if (c->evptype == EVP_rc4) { |
bf8269a9 | 419 | plen = EVP_X_STATE_LEN(cc->evp); |
420 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
421 | } | |
70fc1609 | 422 | } |