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31652869 | 1 | /* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt 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 | |
31652869 | 40 | #include <sys/types.h> |
41 | ||
00146caa | 42 | #include <openssl/md5.h> |
43 | ||
44 | #include <string.h> | |
31652869 | 45 | #include <stdarg.h> |
00146caa | 46 | |
a8be9f80 | 47 | #include "xmalloc.h" |
42f11eb2 | 48 | #include "log.h" |
49 | #include "cipher.h" | |
8efc0c15 | 50 | |
601b831d | 51 | /* compatibility with old or broken OpenSSL versions */ |
52 | #include "openbsd-compat/openssl-compat.h" | |
53 | ||
3b6e3da9 | 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); | |
25b66522 | 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); | |
8efc0c15 | 59 | |
3ee832e5 | 60 | struct Cipher { |
61 | char *name; | |
62 | int number; /* for ssh1 only */ | |
63 | u_int block_size; | |
64 | u_int key_len; | |
74a66cc8 | 65 | u_int discard_len; |
7b5edc2b | 66 | const EVP_CIPHER *(*evptype)(void); |
70fc1609 | 67 | } ciphers[] = { |
74a66cc8 | 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 }, | |
70fc1609 | 72 | |
74a66cc8 | 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 }, | |
74a66cc8 | 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 }, | |
135247df | 82 | { "rijndael-cbc@lysator.liu.se", |
74a66cc8 | 83 | SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, |
74a66cc8 | 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 }, | |
52607c0f | 87 | #ifdef USE_CIPHER_ACSS |
74a66cc8 | 88 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss }, |
268c23e9 | 89 | #endif |
74a66cc8 | 90 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL } |
94ec8c6b | 91 | }; |
92 | ||
93 | /*--*/ | |
94 | ||
762715ce | 95 | u_int |
b6c7b7b7 | 96 | cipher_blocksize(const Cipher *c) |
3ee832e5 | 97 | { |
98 | return (c->block_size); | |
99 | } | |
3ddc795d | 100 | |
762715ce | 101 | u_int |
b6c7b7b7 | 102 | cipher_keylen(const Cipher *c) |
3ee832e5 | 103 | { |
104 | return (c->key_len); | |
105 | } | |
3ddc795d | 106 | |
762715ce | 107 | u_int |
b6c7b7b7 | 108 | cipher_get_number(const Cipher *c) |
bf8269a9 | 109 | { |
110 | return (c->number); | |
111 | } | |
3ee832e5 | 112 | |
1e3b8b07 | 113 | u_int |
94ec8c6b | 114 | cipher_mask_ssh1(int client) |
8ce64345 | 115 | { |
1e3b8b07 | 116 | u_int mask = 0; |
184eed6a | 117 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
94ec8c6b | 118 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
119 | if (client) { | |
120 | mask |= 1 << SSH_CIPHER_DES; | |
121 | } | |
5260325f | 122 | return mask; |
8efc0c15 | 123 | } |
94ec8c6b | 124 | |
125 | Cipher * | |
126 | cipher_by_name(const char *name) | |
8ce64345 | 127 | { |
94ec8c6b | 128 | Cipher *c; |
129 | for (c = ciphers; c->name != NULL; c++) | |
3ebbcf03 | 130 | if (strcmp(c->name, name) == 0) |
94ec8c6b | 131 | return c; |
132 | return NULL; | |
8ce64345 | 133 | } |
8efc0c15 | 134 | |
94ec8c6b | 135 | Cipher * |
136 | cipher_by_number(int id) | |
8efc0c15 | 137 | { |
94ec8c6b | 138 | Cipher *c; |
139 | for (c = ciphers; c->name != NULL; c++) | |
140 | if (c->number == id) | |
141 | return c; | |
142 | return NULL; | |
8efc0c15 | 143 | } |
144 | ||
a8be9f80 | 145 | #define CIPHER_SEP "," |
146 | int | |
147 | ciphers_valid(const char *names) | |
148 | { | |
94ec8c6b | 149 | Cipher *c; |
ca75d7de | 150 | char *cipher_list, *cp; |
a8be9f80 | 151 | char *p; |
a8be9f80 | 152 | |
71276795 | 153 | if (names == NULL || strcmp(names, "") == 0) |
a8be9f80 | 154 | return 0; |
ca75d7de | 155 | cipher_list = cp = xstrdup(names); |
94ec8c6b | 156 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
184eed6a | 157 | (p = strsep(&cp, CIPHER_SEP))) { |
94ec8c6b | 158 | c = cipher_by_name(p); |
159 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
160 | debug("bad cipher %s [%s]", p, names); | |
ca75d7de | 161 | xfree(cipher_list); |
a8be9f80 | 162 | return 0; |
94ec8c6b | 163 | } else { |
33de75a3 | 164 | debug3("cipher ok: %s [%s]", p, names); |
a8be9f80 | 165 | } |
166 | } | |
33de75a3 | 167 | debug3("ciphers ok: [%s]", names); |
ca75d7de | 168 | xfree(cipher_list); |
a8be9f80 | 169 | return 1; |
170 | } | |
171 | ||
aa3378df | 172 | /* |
173 | * Parses the name of the cipher. Returns the number of the corresponding | |
174 | * cipher, or -1 on error. | |
175 | */ | |
8efc0c15 | 176 | |
177 | int | |
178 | cipher_number(const char *name) | |
179 | { | |
94ec8c6b | 180 | Cipher *c; |
71276795 | 181 | if (name == NULL) |
182 | return -1; | |
3ebbcf03 | 183 | for (c = ciphers; c->name != NULL; c++) |
184 | if (strcasecmp(c->name, name) == 0) | |
185 | return c->number; | |
186 | return -1; | |
94ec8c6b | 187 | } |
188 | ||
189 | char * | |
190 | cipher_name(int id) | |
191 | { | |
192 | Cipher *c = cipher_by_number(id); | |
193 | return (c==NULL) ? "<unknown>" : c->name; | |
194 | } | |
195 | ||
196 | void | |
70fc1609 | 197 | cipher_init(CipherContext *cc, Cipher *cipher, |
198 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, | |
ca75d7de | 199 | int do_encrypt) |
94ec8c6b | 200 | { |
70fc1609 | 201 | static int dowarn = 1; |
a068d86f | 202 | #ifdef SSH_OLD_EVP |
203 | EVP_CIPHER *type; | |
204 | #else | |
70fc1609 | 205 | const EVP_CIPHER *type; |
206 | int klen; | |
52607c0f | 207 | #endif |
74a66cc8 | 208 | u_char *junk, *discard; |
70fc1609 | 209 | |
210 | if (cipher->number == SSH_CIPHER_DES) { | |
211 | if (dowarn) { | |
212 | error("Warning: use of DES is strongly discouraged " | |
213 | "due to cryptographic weaknesses"); | |
214 | dowarn = 0; | |
215 | } | |
216 | if (keylen > 8) | |
217 | keylen = 8; | |
218 | } | |
219 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
220 | ||
94ec8c6b | 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); | |
227 | cc->cipher = cipher; | |
70fc1609 | 228 | |
229 | type = (*cipher->evptype)(); | |
230 | ||
231 | EVP_CIPHER_CTX_init(&cc->evp); | |
a068d86f | 232 | #ifdef SSH_OLD_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; | |
237 | } | |
238 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
9ea217e8 | 239 | (do_encrypt == CIPHER_ENCRYPT)); |
a068d86f | 240 | #else |
70fc1609 | 241 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
ca75d7de | 242 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
70fc1609 | 243 | fatal("cipher_init: EVP_CipherInit failed for %s", |
244 | cipher->name); | |
245 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
2ceb8101 | 246 | if (klen > 0 && keylen != (u_int)klen) { |
a77673cc | 247 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
70fc1609 | 248 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
249 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
250 | klen, keylen); | |
251 | } | |
252 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
253 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
254 | cipher->name); | |
a068d86f | 255 | #endif |
74a66cc8 | 256 | |
56964485 | 257 | if (cipher->discard_len > 0) { |
74a66cc8 | 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); | |
264 | xfree(junk); | |
265 | xfree(discard); | |
266 | } | |
94ec8c6b | 267 | } |
268 | ||
269 | void | |
3ee832e5 | 270 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
94ec8c6b | 271 | { |
272 | if (len % cc->cipher->block_size) | |
273 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
70fc1609 | 274 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
275 | fatal("evp_crypt: EVP_Cipher failed"); | |
94ec8c6b | 276 | } |
277 | ||
278 | void | |
3ee832e5 | 279 | cipher_cleanup(CipherContext *cc) |
94ec8c6b | 280 | { |
70fc1609 | 281 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
282 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
8efc0c15 | 283 | } |
284 | ||
aa3378df | 285 | /* |
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. | |
288 | */ | |
8efc0c15 | 289 | |
6ae2364d | 290 | void |
94ec8c6b | 291 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, |
ca75d7de | 292 | const char *passphrase, int do_encrypt) |
8efc0c15 | 293 | { |
5260325f | 294 | MD5_CTX md; |
1e3b8b07 | 295 | u_char digest[16]; |
5260325f | 296 | |
297 | MD5_Init(&md); | |
94ec8c6b | 298 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); |
5260325f | 299 | MD5_Final(digest, &md); |
300 | ||
ca75d7de | 301 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
5260325f | 302 | |
303 | memset(digest, 0, sizeof(digest)); | |
304 | memset(&md, 0, sizeof(md)); | |
8efc0c15 | 305 | } |
70fc1609 | 306 | |
762715ce | 307 | /* |
bf8269a9 | 308 | * Exports an IV from the CipherContext required to export the key |
309 | * state back from the unprivileged child to the privileged parent | |
310 | * process. | |
311 | */ | |
312 | ||
313 | int | |
b6c7b7b7 | 314 | cipher_get_keyiv_len(const CipherContext *cc) |
bf8269a9 | 315 | { |
316 | Cipher *c = cc->cipher; | |
317 | int ivlen; | |
318 | ||
319 | if (c->number == SSH_CIPHER_3DES) | |
320 | ivlen = 24; | |
321 | else | |
322 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
323 | return (ivlen); | |
324 | } | |
325 | ||
326 | void | |
327 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
328 | { | |
329 | Cipher *c = cc->cipher; | |
bf8269a9 | 330 | int evplen; |
331 | ||
332 | switch (c->number) { | |
333 | case SSH_CIPHER_SSH2: | |
334 | case SSH_CIPHER_DES: | |
335 | case SSH_CIPHER_BLOWFISH: | |
336 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
2ceb8101 | 337 | if (evplen <= 0) |
bf8269a9 | 338 | return; |
2ceb8101 | 339 | if ((u_int)evplen != len) |
1588c277 | 340 | fatal("%s: wrong iv length %d != %d", __func__, |
bf8269a9 | 341 | evplen, len); |
e5146707 | 342 | #ifdef USE_BUILTIN_RIJNDAEL |
18ae3c67 | 343 | if (c->evptype == evp_rijndael) |
344 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
345 | else | |
135247df | 346 | #endif |
25b66522 | 347 | if (c->evptype == evp_aes_128_ctr) |
348 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
349 | else | |
18ae3c67 | 350 | memcpy(iv, cc->evp.iv, len); |
351 | break; | |
352 | case SSH_CIPHER_3DES: | |
353 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
bf8269a9 | 354 | break; |
bf8269a9 | 355 | default: |
1588c277 | 356 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 357 | } |
bf8269a9 | 358 | } |
359 | ||
360 | void | |
361 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
362 | { | |
363 | Cipher *c = cc->cipher; | |
bf8269a9 | 364 | int evplen = 0; |
365 | ||
366 | switch (c->number) { | |
367 | case SSH_CIPHER_SSH2: | |
368 | case SSH_CIPHER_DES: | |
369 | case SSH_CIPHER_BLOWFISH: | |
370 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
371 | if (evplen == 0) | |
372 | return; | |
e5146707 | 373 | #ifdef USE_BUILTIN_RIJNDAEL |
18ae3c67 | 374 | if (c->evptype == evp_rijndael) |
375 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
376 | else | |
135247df | 377 | #endif |
25b66522 | 378 | if (c->evptype == evp_aes_128_ctr) |
379 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
380 | else | |
18ae3c67 | 381 | memcpy(cc->evp.iv, iv, evplen); |
382 | break; | |
383 | case SSH_CIPHER_3DES: | |
384 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
bf8269a9 | 385 | break; |
bf8269a9 | 386 | default: |
1588c277 | 387 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 388 | } |
bf8269a9 | 389 | } |
390 | ||
391 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
392 | #define EVP_X_STATE(evp) &(evp).c | |
393 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
394 | #else | |
395 | #define EVP_X_STATE(evp) (evp).cipher_data | |
396 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
397 | #endif | |
398 | ||
399 | int | |
b6c7b7b7 | 400 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
bf8269a9 | 401 | { |
402 | Cipher *c = cc->cipher; | |
9459414c | 403 | int plen = 0; |
bf8269a9 | 404 | |
268c23e9 | 405 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
9459414c | 406 | plen = EVP_X_STATE_LEN(cc->evp); |
bf8269a9 | 407 | if (dat == NULL) |
9459414c | 408 | return (plen); |
409 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
bf8269a9 | 410 | } |
bf8269a9 | 411 | return (plen); |
412 | } | |
413 | ||
414 | void | |
415 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
416 | { | |
417 | Cipher *c = cc->cipher; | |
418 | int plen; | |
419 | ||
268c23e9 | 420 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
bf8269a9 | 421 | plen = EVP_X_STATE_LEN(cc->evp); |
422 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
423 | } | |
70fc1609 | 424 | } |