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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" | |
2ceb8101 | 38 | RCSID("$OpenBSD: cipher.c,v 1.76 2005/06/17 02:44:32 djm 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 | |
3b6e3da9 | 46 | extern const EVP_CIPHER *evp_ssh1_bf(void); |
47 | extern const EVP_CIPHER *evp_ssh1_3des(void); | |
48 | extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); | |
25b66522 | 49 | extern const EVP_CIPHER *evp_aes_128_ctr(void); |
50 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
8efc0c15 | 51 | |
3ee832e5 | 52 | struct Cipher { |
53 | char *name; | |
54 | int number; /* for ssh1 only */ | |
55 | u_int block_size; | |
56 | u_int key_len; | |
74a66cc8 | 57 | u_int discard_len; |
7b5edc2b | 58 | const EVP_CIPHER *(*evptype)(void); |
70fc1609 | 59 | } ciphers[] = { |
74a66cc8 | 60 | { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null }, |
61 | { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc }, | |
62 | { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des }, | |
63 | { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf }, | |
70fc1609 | 64 | |
74a66cc8 | 65 | { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc }, |
66 | { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc }, | |
67 | { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc }, | |
68 | { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 }, | |
69 | { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 }, | |
70 | { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 }, | |
74a66cc8 | 71 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc }, |
72 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc }, | |
73 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, | |
135247df | 74 | { "rijndael-cbc@lysator.liu.se", |
74a66cc8 | 75 | SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, |
74a66cc8 | 76 | { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr }, |
77 | { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr }, | |
78 | { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr }, | |
52607c0f | 79 | #ifdef USE_CIPHER_ACSS |
74a66cc8 | 80 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss }, |
268c23e9 | 81 | #endif |
74a66cc8 | 82 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL } |
94ec8c6b | 83 | }; |
84 | ||
85 | /*--*/ | |
86 | ||
762715ce | 87 | u_int |
b6c7b7b7 | 88 | cipher_blocksize(const Cipher *c) |
3ee832e5 | 89 | { |
90 | return (c->block_size); | |
91 | } | |
3ddc795d | 92 | |
762715ce | 93 | u_int |
b6c7b7b7 | 94 | cipher_keylen(const Cipher *c) |
3ee832e5 | 95 | { |
96 | return (c->key_len); | |
97 | } | |
3ddc795d | 98 | |
762715ce | 99 | u_int |
b6c7b7b7 | 100 | cipher_get_number(const Cipher *c) |
bf8269a9 | 101 | { |
102 | return (c->number); | |
103 | } | |
3ee832e5 | 104 | |
1e3b8b07 | 105 | u_int |
94ec8c6b | 106 | cipher_mask_ssh1(int client) |
8ce64345 | 107 | { |
1e3b8b07 | 108 | u_int mask = 0; |
184eed6a | 109 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
94ec8c6b | 110 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
111 | if (client) { | |
112 | mask |= 1 << SSH_CIPHER_DES; | |
113 | } | |
5260325f | 114 | return mask; |
8efc0c15 | 115 | } |
94ec8c6b | 116 | |
117 | Cipher * | |
118 | cipher_by_name(const char *name) | |
8ce64345 | 119 | { |
94ec8c6b | 120 | Cipher *c; |
121 | for (c = ciphers; c->name != NULL; c++) | |
3ebbcf03 | 122 | if (strcmp(c->name, name) == 0) |
94ec8c6b | 123 | return c; |
124 | return NULL; | |
8ce64345 | 125 | } |
8efc0c15 | 126 | |
94ec8c6b | 127 | Cipher * |
128 | cipher_by_number(int id) | |
8efc0c15 | 129 | { |
94ec8c6b | 130 | Cipher *c; |
131 | for (c = ciphers; c->name != NULL; c++) | |
132 | if (c->number == id) | |
133 | return c; | |
134 | return NULL; | |
8efc0c15 | 135 | } |
136 | ||
a8be9f80 | 137 | #define CIPHER_SEP "," |
138 | int | |
139 | ciphers_valid(const char *names) | |
140 | { | |
94ec8c6b | 141 | Cipher *c; |
ca75d7de | 142 | char *cipher_list, *cp; |
a8be9f80 | 143 | char *p; |
a8be9f80 | 144 | |
71276795 | 145 | if (names == NULL || strcmp(names, "") == 0) |
a8be9f80 | 146 | return 0; |
ca75d7de | 147 | cipher_list = cp = xstrdup(names); |
94ec8c6b | 148 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
184eed6a | 149 | (p = strsep(&cp, CIPHER_SEP))) { |
94ec8c6b | 150 | c = cipher_by_name(p); |
151 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
152 | debug("bad cipher %s [%s]", p, names); | |
ca75d7de | 153 | xfree(cipher_list); |
a8be9f80 | 154 | return 0; |
94ec8c6b | 155 | } else { |
33de75a3 | 156 | debug3("cipher ok: %s [%s]", p, names); |
a8be9f80 | 157 | } |
158 | } | |
33de75a3 | 159 | debug3("ciphers ok: [%s]", names); |
ca75d7de | 160 | xfree(cipher_list); |
a8be9f80 | 161 | return 1; |
162 | } | |
163 | ||
aa3378df | 164 | /* |
165 | * Parses the name of the cipher. Returns the number of the corresponding | |
166 | * cipher, or -1 on error. | |
167 | */ | |
8efc0c15 | 168 | |
169 | int | |
170 | cipher_number(const char *name) | |
171 | { | |
94ec8c6b | 172 | Cipher *c; |
71276795 | 173 | if (name == NULL) |
174 | return -1; | |
3ebbcf03 | 175 | for (c = ciphers; c->name != NULL; c++) |
176 | if (strcasecmp(c->name, name) == 0) | |
177 | return c->number; | |
178 | return -1; | |
94ec8c6b | 179 | } |
180 | ||
181 | char * | |
182 | cipher_name(int id) | |
183 | { | |
184 | Cipher *c = cipher_by_number(id); | |
185 | return (c==NULL) ? "<unknown>" : c->name; | |
186 | } | |
187 | ||
188 | void | |
70fc1609 | 189 | cipher_init(CipherContext *cc, Cipher *cipher, |
190 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, | |
ca75d7de | 191 | int do_encrypt) |
94ec8c6b | 192 | { |
70fc1609 | 193 | static int dowarn = 1; |
a068d86f | 194 | #ifdef SSH_OLD_EVP |
195 | EVP_CIPHER *type; | |
196 | #else | |
70fc1609 | 197 | const EVP_CIPHER *type; |
198 | int klen; | |
52607c0f | 199 | #endif |
74a66cc8 | 200 | u_char *junk, *discard; |
70fc1609 | 201 | |
202 | if (cipher->number == SSH_CIPHER_DES) { | |
203 | if (dowarn) { | |
204 | error("Warning: use of DES is strongly discouraged " | |
205 | "due to cryptographic weaknesses"); | |
206 | dowarn = 0; | |
207 | } | |
208 | if (keylen > 8) | |
209 | keylen = 8; | |
210 | } | |
211 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
212 | ||
94ec8c6b | 213 | if (keylen < cipher->key_len) |
214 | fatal("cipher_init: key length %d is insufficient for %s.", | |
215 | keylen, cipher->name); | |
216 | if (iv != NULL && ivlen < cipher->block_size) | |
217 | fatal("cipher_init: iv length %d is insufficient for %s.", | |
218 | ivlen, cipher->name); | |
219 | cc->cipher = cipher; | |
70fc1609 | 220 | |
221 | type = (*cipher->evptype)(); | |
222 | ||
223 | EVP_CIPHER_CTX_init(&cc->evp); | |
a068d86f | 224 | #ifdef SSH_OLD_EVP |
225 | if (type->key_len > 0 && type->key_len != keylen) { | |
226 | debug("cipher_init: set keylen (%d -> %d)", | |
227 | type->key_len, keylen); | |
228 | type->key_len = keylen; | |
229 | } | |
230 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
9ea217e8 | 231 | (do_encrypt == CIPHER_ENCRYPT)); |
a068d86f | 232 | #else |
70fc1609 | 233 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
ca75d7de | 234 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
70fc1609 | 235 | fatal("cipher_init: EVP_CipherInit failed for %s", |
236 | cipher->name); | |
237 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
2ceb8101 | 238 | if (klen > 0 && keylen != (u_int)klen) { |
a77673cc | 239 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
70fc1609 | 240 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
241 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
242 | klen, keylen); | |
243 | } | |
244 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
245 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
246 | cipher->name); | |
a068d86f | 247 | #endif |
74a66cc8 | 248 | |
249 | if (cipher->discard_len > 0) { | |
250 | junk = xmalloc(cipher->discard_len); | |
251 | discard = xmalloc(cipher->discard_len); | |
252 | if (EVP_Cipher(&cc->evp, discard, junk, | |
253 | cipher->discard_len) == 0) | |
254 | fatal("evp_crypt: EVP_Cipher failed during discard"); | |
255 | memset(discard, 0, cipher->discard_len); | |
256 | xfree(junk); | |
257 | xfree(discard); | |
258 | } | |
94ec8c6b | 259 | } |
260 | ||
261 | void | |
3ee832e5 | 262 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
94ec8c6b | 263 | { |
264 | if (len % cc->cipher->block_size) | |
265 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
70fc1609 | 266 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
267 | fatal("evp_crypt: EVP_Cipher failed"); | |
94ec8c6b | 268 | } |
269 | ||
270 | void | |
3ee832e5 | 271 | cipher_cleanup(CipherContext *cc) |
94ec8c6b | 272 | { |
70fc1609 | 273 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
274 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
8efc0c15 | 275 | } |
276 | ||
aa3378df | 277 | /* |
278 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
279 | * passphrase and using the resulting 16 bytes as the key. | |
280 | */ | |
8efc0c15 | 281 | |
6ae2364d | 282 | void |
94ec8c6b | 283 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, |
ca75d7de | 284 | const char *passphrase, int do_encrypt) |
8efc0c15 | 285 | { |
5260325f | 286 | MD5_CTX md; |
1e3b8b07 | 287 | u_char digest[16]; |
5260325f | 288 | |
289 | MD5_Init(&md); | |
94ec8c6b | 290 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); |
5260325f | 291 | MD5_Final(digest, &md); |
292 | ||
ca75d7de | 293 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
5260325f | 294 | |
295 | memset(digest, 0, sizeof(digest)); | |
296 | memset(&md, 0, sizeof(md)); | |
8efc0c15 | 297 | } |
70fc1609 | 298 | |
762715ce | 299 | /* |
bf8269a9 | 300 | * Exports an IV from the CipherContext required to export the key |
301 | * state back from the unprivileged child to the privileged parent | |
302 | * process. | |
303 | */ | |
304 | ||
305 | int | |
b6c7b7b7 | 306 | cipher_get_keyiv_len(const CipherContext *cc) |
bf8269a9 | 307 | { |
308 | Cipher *c = cc->cipher; | |
309 | int ivlen; | |
310 | ||
311 | if (c->number == SSH_CIPHER_3DES) | |
312 | ivlen = 24; | |
313 | else | |
314 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
315 | return (ivlen); | |
316 | } | |
317 | ||
318 | void | |
319 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
320 | { | |
321 | Cipher *c = cc->cipher; | |
bf8269a9 | 322 | int evplen; |
323 | ||
324 | switch (c->number) { | |
325 | case SSH_CIPHER_SSH2: | |
326 | case SSH_CIPHER_DES: | |
327 | case SSH_CIPHER_BLOWFISH: | |
328 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
2ceb8101 | 329 | if (evplen <= 0) |
bf8269a9 | 330 | return; |
2ceb8101 | 331 | if ((u_int)evplen != len) |
1588c277 | 332 | fatal("%s: wrong iv length %d != %d", __func__, |
bf8269a9 | 333 | evplen, len); |
135247df | 334 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
18ae3c67 | 335 | if (c->evptype == evp_rijndael) |
336 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
337 | else | |
135247df | 338 | #endif |
25b66522 | 339 | if (c->evptype == evp_aes_128_ctr) |
340 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
341 | else | |
18ae3c67 | 342 | memcpy(iv, cc->evp.iv, len); |
343 | break; | |
344 | case SSH_CIPHER_3DES: | |
345 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
bf8269a9 | 346 | break; |
bf8269a9 | 347 | default: |
1588c277 | 348 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 349 | } |
bf8269a9 | 350 | } |
351 | ||
352 | void | |
353 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
354 | { | |
355 | Cipher *c = cc->cipher; | |
bf8269a9 | 356 | int evplen = 0; |
357 | ||
358 | switch (c->number) { | |
359 | case SSH_CIPHER_SSH2: | |
360 | case SSH_CIPHER_DES: | |
361 | case SSH_CIPHER_BLOWFISH: | |
362 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
363 | if (evplen == 0) | |
364 | return; | |
135247df | 365 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
18ae3c67 | 366 | if (c->evptype == evp_rijndael) |
367 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
368 | else | |
135247df | 369 | #endif |
25b66522 | 370 | if (c->evptype == evp_aes_128_ctr) |
371 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
372 | else | |
18ae3c67 | 373 | memcpy(cc->evp.iv, iv, evplen); |
374 | break; | |
375 | case SSH_CIPHER_3DES: | |
376 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
bf8269a9 | 377 | break; |
bf8269a9 | 378 | default: |
1588c277 | 379 | fatal("%s: bad cipher %d", __func__, c->number); |
bf8269a9 | 380 | } |
bf8269a9 | 381 | } |
382 | ||
383 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
384 | #define EVP_X_STATE(evp) &(evp).c | |
385 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
386 | #else | |
387 | #define EVP_X_STATE(evp) (evp).cipher_data | |
388 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
389 | #endif | |
390 | ||
391 | int | |
b6c7b7b7 | 392 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
bf8269a9 | 393 | { |
394 | Cipher *c = cc->cipher; | |
9459414c | 395 | int plen = 0; |
bf8269a9 | 396 | |
268c23e9 | 397 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
9459414c | 398 | plen = EVP_X_STATE_LEN(cc->evp); |
bf8269a9 | 399 | if (dat == NULL) |
9459414c | 400 | return (plen); |
401 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
bf8269a9 | 402 | } |
bf8269a9 | 403 | return (plen); |
404 | } | |
405 | ||
406 | void | |
407 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
408 | { | |
409 | Cipher *c = cc->cipher; | |
410 | int plen; | |
411 | ||
268c23e9 | 412 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
bf8269a9 | 413 | plen = EVP_X_STATE_LEN(cc->evp); |
414 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
415 | } | |
70fc1609 | 416 | } |