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5262cbfb | 1 | /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * | |
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. | |
15 | * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. | |
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. | |
25 | * | |
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. | |
36 | */ | |
37 | ||
38 | #include "includes.h" | |
30460aeb | 39 | |
40 | #include <sys/types.h> | |
41 | ||
42 | #include <openssl/md5.h> | |
43 | ||
44 | #include <string.h> | |
45 | #include <stdarg.h> | |
3c0ef626 | 46 | |
47 | #include "xmalloc.h" | |
48 | #include "log.h" | |
49 | #include "cipher.h" | |
50 | ||
2ce0bfe4 | 51 | /* compatibility with old or broken OpenSSL versions */ |
52 | #include "openbsd-compat/openssl-compat.h" | |
540d72c3 | 53 | |
7cac2b65 | 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); | |
57 | extern const EVP_CIPHER *evp_aes_128_ctr(void); | |
fa7499cc | 58 | extern const EVP_CIPHER *evp_aes_ctr_mt(void); |
7cac2b65 | 59 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); |
905081a4 | 60 | |
61 | struct Cipher { | |
62 | char *name; | |
63 | int number; /* for ssh1 only */ | |
64 | u_int block_size; | |
65 | u_int key_len; | |
2ce0bfe4 | 66 | u_int discard_len; |
5262cbfb | 67 | u_int cbc_mode; |
44a053a3 | 68 | const EVP_CIPHER *(*evptype)(void); |
905081a4 | 69 | } ciphers[] = { |
5262cbfb | 70 | { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null }, |
71 | { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc }, | |
72 | { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des }, | |
73 | { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf }, | |
2ce0bfe4 | 74 | |
5262cbfb | 75 | { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc }, |
76 | { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc }, | |
77 | { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc }, | |
78 | { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 }, | |
79 | { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 }, | |
80 | { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 }, | |
81 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc }, | |
82 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc }, | |
83 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, | |
350391c5 | 84 | { "rijndael-cbc@lysator.liu.se", |
5262cbfb | 85 | SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, |
86 | { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_ctr_mt }, | |
87 | { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_ctr_mt }, | |
88 | { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_ctr_mt }, | |
2ce0bfe4 | 89 | #ifdef USE_CIPHER_ACSS |
5262cbfb | 90 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss }, |
29d88157 | 91 | #endif |
5262cbfb | 92 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL } |
905081a4 | 93 | }; |
3c0ef626 | 94 | |
905081a4 | 95 | /*--*/ |
3c0ef626 | 96 | |
905081a4 | 97 | u_int |
540d72c3 | 98 | cipher_blocksize(const Cipher *c) |
3c0ef626 | 99 | { |
905081a4 | 100 | return (c->block_size); |
3c0ef626 | 101 | } |
276b07a3 | 102 | |
905081a4 | 103 | u_int |
540d72c3 | 104 | cipher_keylen(const Cipher *c) |
3c0ef626 | 105 | { |
905081a4 | 106 | return (c->key_len); |
3c0ef626 | 107 | } |
276b07a3 | 108 | |
905081a4 | 109 | u_int |
540d72c3 | 110 | cipher_get_number(const Cipher *c) |
3c0ef626 | 111 | { |
905081a4 | 112 | return (c->number); |
3c0ef626 | 113 | } |
114 | ||
5262cbfb | 115 | u_int |
116 | cipher_is_cbc(const Cipher *c) | |
117 | { | |
118 | return (c->cbc_mode); | |
119 | } | |
120 | ||
3c0ef626 | 121 | u_int |
122 | cipher_mask_ssh1(int client) | |
123 | { | |
124 | u_int mask = 0; | |
905081a4 | 125 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
3c0ef626 | 126 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
127 | if (client) { | |
128 | mask |= 1 << SSH_CIPHER_DES; | |
129 | } | |
130 | return mask; | |
131 | } | |
132 | ||
133 | Cipher * | |
134 | cipher_by_name(const char *name) | |
135 | { | |
136 | Cipher *c; | |
137 | for (c = ciphers; c->name != NULL; c++) | |
dfddba3d | 138 | if (strcmp(c->name, name) == 0) |
3c0ef626 | 139 | return c; |
140 | return NULL; | |
141 | } | |
142 | ||
143 | Cipher * | |
144 | cipher_by_number(int id) | |
145 | { | |
146 | Cipher *c; | |
147 | for (c = ciphers; c->name != NULL; c++) | |
148 | if (c->number == id) | |
149 | return c; | |
150 | return NULL; | |
151 | } | |
152 | ||
153 | #define CIPHER_SEP "," | |
154 | int | |
155 | ciphers_valid(const char *names) | |
156 | { | |
157 | Cipher *c; | |
7e82606e | 158 | char *cipher_list, *cp; |
3c0ef626 | 159 | char *p; |
160 | ||
161 | if (names == NULL || strcmp(names, "") == 0) | |
162 | return 0; | |
7e82606e | 163 | cipher_list = cp = xstrdup(names); |
3c0ef626 | 164 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
905081a4 | 165 | (p = strsep(&cp, CIPHER_SEP))) { |
3c0ef626 | 166 | c = cipher_by_name(p); |
8af0406b | 167 | if (c == NULL || (c->number != SSH_CIPHER_SSH2 && |
168 | c->number != SSH_CIPHER_NONE)) { | |
3c0ef626 | 169 | debug("bad cipher %s [%s]", p, names); |
7e82606e | 170 | xfree(cipher_list); |
3c0ef626 | 171 | return 0; |
172 | } else { | |
173 | debug3("cipher ok: %s [%s]", p, names); | |
174 | } | |
175 | } | |
176 | debug3("ciphers ok: [%s]", names); | |
7e82606e | 177 | xfree(cipher_list); |
3c0ef626 | 178 | return 1; |
179 | } | |
180 | ||
181 | /* | |
182 | * Parses the name of the cipher. Returns the number of the corresponding | |
183 | * cipher, or -1 on error. | |
184 | */ | |
185 | ||
186 | int | |
187 | cipher_number(const char *name) | |
188 | { | |
189 | Cipher *c; | |
190 | if (name == NULL) | |
191 | return -1; | |
dfddba3d | 192 | for (c = ciphers; c->name != NULL; c++) |
193 | if (strcasecmp(c->name, name) == 0) | |
194 | return c->number; | |
195 | return -1; | |
3c0ef626 | 196 | } |
197 | ||
198 | char * | |
199 | cipher_name(int id) | |
200 | { | |
201 | Cipher *c = cipher_by_number(id); | |
202 | return (c==NULL) ? "<unknown>" : c->name; | |
203 | } | |
204 | ||
205 | void | |
206 | cipher_init(CipherContext *cc, Cipher *cipher, | |
905081a4 | 207 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
7e82606e | 208 | int do_encrypt) |
3c0ef626 | 209 | { |
905081a4 | 210 | static int dowarn = 1; |
350391c5 | 211 | #ifdef SSH_OLD_EVP |
212 | EVP_CIPHER *type; | |
213 | #else | |
905081a4 | 214 | const EVP_CIPHER *type; |
215 | int klen; | |
2ce0bfe4 | 216 | #endif |
217 | u_char *junk, *discard; | |
905081a4 | 218 | |
219 | if (cipher->number == SSH_CIPHER_DES) { | |
220 | if (dowarn) { | |
221 | error("Warning: use of DES is strongly discouraged " | |
222 | "due to cryptographic weaknesses"); | |
223 | dowarn = 0; | |
224 | } | |
225 | if (keylen > 8) | |
226 | keylen = 8; | |
227 | } | |
228 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
229 | ||
3c0ef626 | 230 | if (keylen < cipher->key_len) |
231 | fatal("cipher_init: key length %d is insufficient for %s.", | |
232 | keylen, cipher->name); | |
233 | if (iv != NULL && ivlen < cipher->block_size) | |
234 | fatal("cipher_init: iv length %d is insufficient for %s.", | |
235 | ivlen, cipher->name); | |
236 | cc->cipher = cipher; | |
905081a4 | 237 | |
238 | type = (*cipher->evptype)(); | |
239 | ||
240 | EVP_CIPHER_CTX_init(&cc->evp); | |
350391c5 | 241 | #ifdef SSH_OLD_EVP |
242 | if (type->key_len > 0 && type->key_len != keylen) { | |
243 | debug("cipher_init: set keylen (%d -> %d)", | |
244 | type->key_len, keylen); | |
245 | type->key_len = keylen; | |
246 | } | |
247 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
7e82606e | 248 | (do_encrypt == CIPHER_ENCRYPT)); |
350391c5 | 249 | #else |
905081a4 | 250 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
7e82606e | 251 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
905081a4 | 252 | fatal("cipher_init: EVP_CipherInit failed for %s", |
253 | cipher->name); | |
254 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
2ce0bfe4 | 255 | if (klen > 0 && keylen != (u_int)klen) { |
bfe49944 | 256 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
905081a4 | 257 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
258 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
259 | klen, keylen); | |
260 | } | |
261 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
262 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
263 | cipher->name); | |
350391c5 | 264 | #endif |
2ce0bfe4 | 265 | |
266 | if (cipher->discard_len > 0) { | |
267 | junk = xmalloc(cipher->discard_len); | |
268 | discard = xmalloc(cipher->discard_len); | |
269 | if (EVP_Cipher(&cc->evp, discard, junk, | |
270 | cipher->discard_len) == 0) | |
271 | fatal("evp_crypt: EVP_Cipher failed during discard"); | |
272 | memset(discard, 0, cipher->discard_len); | |
273 | xfree(junk); | |
274 | xfree(discard); | |
275 | } | |
3c0ef626 | 276 | } |
277 | ||
278 | void | |
905081a4 | 279 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
3c0ef626 | 280 | { |
281 | if (len % cc->cipher->block_size) | |
282 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
905081a4 | 283 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
284 | fatal("evp_crypt: EVP_Cipher failed"); | |
3c0ef626 | 285 | } |
286 | ||
287 | void | |
905081a4 | 288 | cipher_cleanup(CipherContext *cc) |
3c0ef626 | 289 | { |
905081a4 | 290 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
291 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
3c0ef626 | 292 | } |
293 | ||
294 | /* | |
295 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
296 | * passphrase and using the resulting 16 bytes as the key. | |
297 | */ | |
298 | ||
299 | void | |
300 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, | |
7e82606e | 301 | const char *passphrase, int do_encrypt) |
3c0ef626 | 302 | { |
303 | MD5_CTX md; | |
304 | u_char digest[16]; | |
305 | ||
306 | MD5_Init(&md); | |
307 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); | |
308 | MD5_Final(digest, &md); | |
309 | ||
7e82606e | 310 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
3c0ef626 | 311 | |
312 | memset(digest, 0, sizeof(digest)); | |
313 | memset(&md, 0, sizeof(md)); | |
314 | } | |
905081a4 | 315 | |
905081a4 | 316 | /* |
317 | * Exports an IV from the CipherContext required to export the key | |
318 | * state back from the unprivileged child to the privileged parent | |
319 | * process. | |
320 | */ | |
321 | ||
322 | int | |
540d72c3 | 323 | cipher_get_keyiv_len(const CipherContext *cc) |
905081a4 | 324 | { |
325 | Cipher *c = cc->cipher; | |
326 | int ivlen; | |
327 | ||
328 | if (c->number == SSH_CIPHER_3DES) | |
329 | ivlen = 24; | |
330 | else | |
331 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
332 | return (ivlen); | |
333 | } | |
334 | ||
335 | void | |
336 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
337 | { | |
338 | Cipher *c = cc->cipher; | |
905081a4 | 339 | int evplen; |
340 | ||
341 | switch (c->number) { | |
473db5ab | 342 | case SSH_CIPHER_NONE: |
905081a4 | 343 | case SSH_CIPHER_SSH2: |
344 | case SSH_CIPHER_DES: | |
345 | case SSH_CIPHER_BLOWFISH: | |
346 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
2ce0bfe4 | 347 | if (evplen <= 0) |
905081a4 | 348 | return; |
2ce0bfe4 | 349 | if ((u_int)evplen != len) |
44a053a3 | 350 | fatal("%s: wrong iv length %d != %d", __func__, |
905081a4 | 351 | evplen, len); |
08822d99 | 352 | #ifdef USE_BUILTIN_RIJNDAEL |
7cac2b65 | 353 | if (c->evptype == evp_rijndael) |
354 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
355 | else | |
44a053a3 | 356 | #endif |
7cac2b65 | 357 | if (c->evptype == evp_aes_128_ctr) |
358 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
359 | else | |
360 | memcpy(iv, cc->evp.iv, len); | |
361 | break; | |
362 | case SSH_CIPHER_3DES: | |
363 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
905081a4 | 364 | break; |
905081a4 | 365 | default: |
44a053a3 | 366 | fatal("%s: bad cipher %d", __func__, c->number); |
905081a4 | 367 | } |
905081a4 | 368 | } |
369 | ||
370 | void | |
371 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
372 | { | |
373 | Cipher *c = cc->cipher; | |
905081a4 | 374 | int evplen = 0; |
375 | ||
376 | switch (c->number) { | |
473db5ab | 377 | case SSH_CIPHER_NONE: |
905081a4 | 378 | case SSH_CIPHER_SSH2: |
379 | case SSH_CIPHER_DES: | |
380 | case SSH_CIPHER_BLOWFISH: | |
381 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
382 | if (evplen == 0) | |
383 | return; | |
08822d99 | 384 | #ifdef USE_BUILTIN_RIJNDAEL |
7cac2b65 | 385 | if (c->evptype == evp_rijndael) |
386 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
387 | else | |
44a053a3 | 388 | #endif |
7cac2b65 | 389 | if (c->evptype == evp_aes_128_ctr) |
390 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
391 | else | |
392 | memcpy(cc->evp.iv, iv, evplen); | |
393 | break; | |
394 | case SSH_CIPHER_3DES: | |
395 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
905081a4 | 396 | break; |
905081a4 | 397 | default: |
44a053a3 | 398 | fatal("%s: bad cipher %d", __func__, c->number); |
905081a4 | 399 | } |
905081a4 | 400 | } |
401 | ||
402 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
403 | #define EVP_X_STATE(evp) &(evp).c | |
404 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
405 | #else | |
406 | #define EVP_X_STATE(evp) (evp).cipher_data | |
407 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
408 | #endif | |
409 | ||
410 | int | |
540d72c3 | 411 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
905081a4 | 412 | { |
413 | Cipher *c = cc->cipher; | |
44a053a3 | 414 | int plen = 0; |
905081a4 | 415 | |
540d72c3 | 416 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
44a053a3 | 417 | plen = EVP_X_STATE_LEN(cc->evp); |
905081a4 | 418 | if (dat == NULL) |
44a053a3 | 419 | return (plen); |
420 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
905081a4 | 421 | } |
905081a4 | 422 | return (plen); |
423 | } | |
424 | ||
425 | void | |
426 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
427 | { | |
428 | Cipher *c = cc->cipher; | |
429 | int plen; | |
430 | ||
540d72c3 | 431 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
905081a4 | 432 | plen = EVP_X_STATE_LEN(cc->evp); |
433 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
434 | } | |
435 | } |