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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" | |
996d5e62 | 38 | RCSID("$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> | |
e9a17296 | 45 | |
700318f3 | 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 | ||
f5799ae1 | 51 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
0fff78ff | 52 | extern const EVP_CIPHER *evp_rijndael(void); |
53 | extern void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
f5799ae1 | 54 | #endif |
cdd66111 | 55 | |
56 | #if !defined(EVP_CTRL_SET_ACSS_MODE) | |
57 | # if (OPENSSL_VERSION_NUMBER >= 0x00907000L) | |
58 | extern 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 | ||
0fff78ff | 66 | extern const EVP_CIPHER *evp_ssh1_bf(void); |
67 | extern const EVP_CIPHER *evp_ssh1_3des(void); | |
68 | extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); | |
69 | extern const EVP_CIPHER *evp_aes_128_ctr(void); | |
70 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
e9a17296 | 71 | |
72 | struct Cipher { | |
73 | char *name; | |
74 | int number; /* for ssh1 only */ | |
75 | u_int block_size; | |
76 | u_int key_len; | |
f5799ae1 | 77 | const EVP_CIPHER *(*evptype)(void); |
e9a17296 | 78 | } ciphers[] = { |
c9f39d2c | 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 }, | |
f5799ae1 | 88 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
c9f39d2c | 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 }, | |
700318f3 | 92 | { "rijndael-cbc@lysator.liu.se", |
93 | SSH_CIPHER_SSH2, 16, 32, evp_rijndael }, | |
f5799ae1 | 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 | |
cdd66111 | 101 | #if OPENSSL_VERSION_NUMBER >= 0x00905000L |
c9f39d2c | 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 }, | |
acc3d05e | 105 | #endif |
cdd66111 | 106 | #if defined(EVP_CTRL_SET_ACSS_MODE) |
107 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, EVP_acss }, | |
108 | #endif | |
c9f39d2c | 109 | { NULL, SSH_CIPHER_INVALID, 0, 0, NULL } |
e9a17296 | 110 | }; |
3c0ef626 | 111 | |
e9a17296 | 112 | /*--*/ |
3c0ef626 | 113 | |
700318f3 | 114 | u_int |
cdd66111 | 115 | cipher_blocksize(const Cipher *c) |
3c0ef626 | 116 | { |
e9a17296 | 117 | return (c->block_size); |
3c0ef626 | 118 | } |
680cee3b | 119 | |
700318f3 | 120 | u_int |
cdd66111 | 121 | cipher_keylen(const Cipher *c) |
3c0ef626 | 122 | { |
e9a17296 | 123 | return (c->key_len); |
3c0ef626 | 124 | } |
680cee3b | 125 | |
700318f3 | 126 | u_int |
cdd66111 | 127 | cipher_get_number(const Cipher *c) |
700318f3 | 128 | { |
129 | return (c->number); | |
130 | } | |
3c0ef626 | 131 | |
3c0ef626 | 132 | u_int |
133 | cipher_mask_ssh1(int client) | |
134 | { | |
135 | u_int mask = 0; | |
e9a17296 | 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 | ||
144 | Cipher * | |
145 | cipher_by_name(const char *name) | |
146 | { | |
147 | Cipher *c; | |
148 | for (c = ciphers; c->name != NULL; c++) | |
996d5e62 | 149 | if (strcmp(c->name, name) == 0) |
3c0ef626 | 150 | return c; |
151 | return NULL; | |
152 | } | |
153 | ||
154 | Cipher * | |
155 | cipher_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 "," | |
165 | int | |
166 | ciphers_valid(const char *names) | |
167 | { | |
168 | Cipher *c; | |
c9f39d2c | 169 | char *cipher_list, *cp; |
3c0ef626 | 170 | char *p; |
171 | ||
172 | if (names == NULL || strcmp(names, "") == 0) | |
173 | return 0; | |
c9f39d2c | 174 | cipher_list = cp = xstrdup(names); |
3c0ef626 | 175 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
e9a17296 | 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); | |
c9f39d2c | 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); | |
c9f39d2c | 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 | ||
196 | int | |
197 | cipher_number(const char *name) | |
198 | { | |
199 | Cipher *c; | |
200 | if (name == NULL) | |
201 | return -1; | |
996d5e62 | 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 | ||
208 | char * | |
209 | cipher_name(int id) | |
210 | { | |
211 | Cipher *c = cipher_by_number(id); | |
212 | return (c==NULL) ? "<unknown>" : c->name; | |
213 | } | |
214 | ||
215 | void | |
216 | cipher_init(CipherContext *cc, Cipher *cipher, | |
e9a17296 | 217 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
c9f39d2c | 218 | int do_encrypt) |
3c0ef626 | 219 | { |
e9a17296 | 220 | static int dowarn = 1; |
700318f3 | 221 | #ifdef SSH_OLD_EVP |
222 | EVP_CIPHER *type; | |
223 | #else | |
e9a17296 | 224 | const EVP_CIPHER *type; |
700318f3 | 225 | #endif |
e9a17296 | 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; | |
e9a17296 | 246 | |
247 | type = (*cipher->evptype)(); | |
248 | ||
249 | EVP_CIPHER_CTX_init(&cc->evp); | |
700318f3 | 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, | |
c9f39d2c | 257 | (do_encrypt == CIPHER_ENCRYPT)); |
700318f3 | 258 | #else |
e9a17296 | 259 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
c9f39d2c | 260 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
e9a17296 | 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) { | |
6a9b3198 | 265 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
e9a17296 | 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); | |
700318f3 | 273 | #endif |
3c0ef626 | 274 | } |
275 | ||
276 | void | |
e9a17296 | 277 | cipher_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); | |
700318f3 | 281 | #ifdef SSH_OLD_EVP |
282 | EVP_Cipher(&cc->evp, dest, (u_char *)src, len); | |
283 | #else | |
e9a17296 | 284 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
285 | fatal("evp_crypt: EVP_Cipher failed"); | |
700318f3 | 286 | #endif |
3c0ef626 | 287 | } |
288 | ||
289 | void | |
e9a17296 | 290 | cipher_cleanup(CipherContext *cc) |
3c0ef626 | 291 | { |
700318f3 | 292 | #ifdef SSH_OLD_EVP |
293 | EVP_CIPHER_CTX_cleanup(&cc->evp); | |
294 | #else | |
e9a17296 | 295 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
296 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
700318f3 | 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 | ||
305 | void | |
306 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, | |
c9f39d2c | 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 | ||
c9f39d2c | 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 | } | |
e9a17296 | 321 | |
700318f3 | 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 | ||
328 | int | |
cdd66111 | 329 | cipher_get_keyiv_len(const CipherContext *cc) |
700318f3 | 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 | ||
341 | void | |
342 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
343 | { | |
344 | Cipher *c = cc->cipher; | |
700318f3 | 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) | |
f5799ae1 | 355 | fatal("%s: wrong iv length %d != %d", __func__, |
700318f3 | 356 | evplen, len); |
f5799ae1 | 357 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
0fff78ff | 358 | if (c->evptype == evp_rijndael) |
359 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
360 | else | |
f5799ae1 | 361 | #endif |
0fff78ff | 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); | |
700318f3 | 369 | break; |
700318f3 | 370 | default: |
f5799ae1 | 371 | fatal("%s: bad cipher %d", __func__, c->number); |
700318f3 | 372 | } |
700318f3 | 373 | } |
374 | ||
375 | void | |
376 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
377 | { | |
378 | Cipher *c = cc->cipher; | |
700318f3 | 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; | |
f5799ae1 | 388 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
0fff78ff | 389 | if (c->evptype == evp_rijndael) |
390 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
391 | else | |
f5799ae1 | 392 | #endif |
0fff78ff | 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); | |
700318f3 | 400 | break; |
700318f3 | 401 | default: |
f5799ae1 | 402 | fatal("%s: bad cipher %d", __func__, c->number); |
700318f3 | 403 | } |
700318f3 | 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 | ||
414 | int | |
cdd66111 | 415 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
700318f3 | 416 | { |
417 | Cipher *c = cc->cipher; | |
f5799ae1 | 418 | int plen = 0; |
700318f3 | 419 | |
cdd66111 | 420 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
f5799ae1 | 421 | plen = EVP_X_STATE_LEN(cc->evp); |
700318f3 | 422 | if (dat == NULL) |
f5799ae1 | 423 | return (plen); |
424 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
700318f3 | 425 | } |
700318f3 | 426 | return (plen); |
427 | } | |
428 | ||
429 | void | |
430 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
431 | { | |
432 | Cipher *c = cc->cipher; | |
433 | int plen; | |
434 | ||
cdd66111 | 435 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
700318f3 | 436 | plen = EVP_X_STATE_LEN(cc->evp); |
437 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
438 | } | |
439 | } |