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2e437378 | 1 | /* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt 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" | |
2e437378 | 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 | ||
34fee935 | 51 | /* compatibility with old or broken OpenSSL versions */ |
52 | #include "openbsd-compat/openssl-compat.h" | |
416fd2a8 | 53 | |
70791e56 | 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); | |
58 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
1e608e42 | 59 | |
60 | struct Cipher { | |
61 | char *name; | |
62 | int number; /* for ssh1 only */ | |
63 | u_int block_size; | |
64 | u_int key_len; | |
34fee935 | 65 | u_int discard_len; |
ff2d7a98 | 66 | const EVP_CIPHER *(*evptype)(void); |
1e608e42 | 67 | } ciphers[] = { |
34fee935 | 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 }, | |
72 | ||
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 }, | |
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 }, | |
2980ea68 | 82 | { "rijndael-cbc@lysator.liu.se", |
34fee935 | 83 | SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, |
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 }, | |
87 | #ifdef USE_CIPHER_ACSS | |
88 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss }, | |
70791e56 | 89 | #endif |
34fee935 | 90 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL } |
1e608e42 | 91 | }; |
3c0ef626 | 92 | |
1e608e42 | 93 | /*--*/ |
3c0ef626 | 94 | |
1e608e42 | 95 | u_int |
416fd2a8 | 96 | cipher_blocksize(const Cipher *c) |
3c0ef626 | 97 | { |
1e608e42 | 98 | return (c->block_size); |
3c0ef626 | 99 | } |
ff2d7a98 | 100 | |
1e608e42 | 101 | u_int |
416fd2a8 | 102 | cipher_keylen(const Cipher *c) |
3c0ef626 | 103 | { |
1e608e42 | 104 | return (c->key_len); |
3c0ef626 | 105 | } |
ff2d7a98 | 106 | |
1e608e42 | 107 | u_int |
416fd2a8 | 108 | cipher_get_number(const Cipher *c) |
3c0ef626 | 109 | { |
1e608e42 | 110 | return (c->number); |
3c0ef626 | 111 | } |
112 | ||
3c0ef626 | 113 | u_int |
114 | cipher_mask_ssh1(int client) | |
115 | { | |
116 | u_int mask = 0; | |
1e608e42 | 117 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
3c0ef626 | 118 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
119 | if (client) { | |
120 | mask |= 1 << SSH_CIPHER_DES; | |
121 | } | |
122 | return mask; | |
123 | } | |
124 | ||
125 | Cipher * | |
126 | cipher_by_name(const char *name) | |
127 | { | |
128 | Cipher *c; | |
129 | for (c = ciphers; c->name != NULL; c++) | |
34fee935 | 130 | if (strcmp(c->name, name) == 0) |
3c0ef626 | 131 | return c; |
132 | return NULL; | |
133 | } | |
134 | ||
135 | Cipher * | |
136 | cipher_by_number(int id) | |
137 | { | |
138 | Cipher *c; | |
139 | for (c = ciphers; c->name != NULL; c++) | |
140 | if (c->number == id) | |
141 | return c; | |
142 | return NULL; | |
143 | } | |
144 | ||
145 | #define CIPHER_SEP "," | |
146 | int | |
147 | ciphers_valid(const char *names) | |
148 | { | |
149 | Cipher *c; | |
1b56ff3d | 150 | char *cipher_list, *cp; |
3c0ef626 | 151 | char *p; |
152 | ||
153 | if (names == NULL || strcmp(names, "") == 0) | |
154 | return 0; | |
1b56ff3d | 155 | cipher_list = cp = xstrdup(names); |
3c0ef626 | 156 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
1e608e42 | 157 | (p = strsep(&cp, CIPHER_SEP))) { |
3c0ef626 | 158 | c = cipher_by_name(p); |
e00da40d | 159 | if (c == NULL || (c->number != SSH_CIPHER_SSH2 && |
160 | c->number != SSH_CIPHER_NONE)) { | |
3c0ef626 | 161 | debug("bad cipher %s [%s]", p, names); |
1b56ff3d | 162 | xfree(cipher_list); |
3c0ef626 | 163 | return 0; |
164 | } else { | |
165 | debug3("cipher ok: %s [%s]", p, names); | |
166 | } | |
167 | } | |
168 | debug3("ciphers ok: [%s]", names); | |
1b56ff3d | 169 | xfree(cipher_list); |
3c0ef626 | 170 | return 1; |
171 | } | |
172 | ||
173 | /* | |
174 | * Parses the name of the cipher. Returns the number of the corresponding | |
175 | * cipher, or -1 on error. | |
176 | */ | |
177 | ||
178 | int | |
179 | cipher_number(const char *name) | |
180 | { | |
181 | Cipher *c; | |
182 | if (name == NULL) | |
183 | return -1; | |
34fee935 | 184 | for (c = ciphers; c->name != NULL; c++) |
185 | if (strcasecmp(c->name, name) == 0) | |
186 | return c->number; | |
187 | return -1; | |
3c0ef626 | 188 | } |
189 | ||
190 | char * | |
191 | cipher_name(int id) | |
192 | { | |
193 | Cipher *c = cipher_by_number(id); | |
194 | return (c==NULL) ? "<unknown>" : c->name; | |
195 | } | |
196 | ||
197 | void | |
198 | cipher_init(CipherContext *cc, Cipher *cipher, | |
1e608e42 | 199 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
1b56ff3d | 200 | int do_encrypt) |
3c0ef626 | 201 | { |
1e608e42 | 202 | static int dowarn = 1; |
2980ea68 | 203 | #ifdef SSH_OLD_EVP |
204 | EVP_CIPHER *type; | |
205 | #else | |
1e608e42 | 206 | const EVP_CIPHER *type; |
207 | int klen; | |
34fee935 | 208 | #endif |
209 | u_char *junk, *discard; | |
1e608e42 | 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 | ||
3c0ef626 | 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; | |
1e608e42 | 229 | |
230 | type = (*cipher->evptype)(); | |
231 | ||
232 | EVP_CIPHER_CTX_init(&cc->evp); | |
2980ea68 | 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, | |
1b56ff3d | 240 | (do_encrypt == CIPHER_ENCRYPT)); |
2980ea68 | 241 | #else |
1e608e42 | 242 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
1b56ff3d | 243 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
1e608e42 | 244 | fatal("cipher_init: EVP_CipherInit failed for %s", |
245 | cipher->name); | |
246 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
34fee935 | 247 | if (klen > 0 && keylen != (u_int)klen) { |
1c14df9e | 248 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
1e608e42 | 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); | |
2980ea68 | 256 | #endif |
34fee935 | 257 | |
258 | if (cipher->discard_len > 0) { | |
259 | junk = xmalloc(cipher->discard_len); | |
260 | discard = xmalloc(cipher->discard_len); | |
261 | if (EVP_Cipher(&cc->evp, discard, junk, | |
262 | cipher->discard_len) == 0) | |
263 | fatal("evp_crypt: EVP_Cipher failed during discard"); | |
264 | memset(discard, 0, cipher->discard_len); | |
265 | xfree(junk); | |
266 | xfree(discard); | |
267 | } | |
3c0ef626 | 268 | } |
269 | ||
270 | void | |
1e608e42 | 271 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
3c0ef626 | 272 | { |
273 | if (len % cc->cipher->block_size) | |
274 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
1e608e42 | 275 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
276 | fatal("evp_crypt: EVP_Cipher failed"); | |
3c0ef626 | 277 | } |
278 | ||
279 | void | |
1e608e42 | 280 | cipher_cleanup(CipherContext *cc) |
3c0ef626 | 281 | { |
1e608e42 | 282 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
283 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
3c0ef626 | 284 | } |
285 | ||
286 | /* | |
287 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
288 | * passphrase and using the resulting 16 bytes as the key. | |
289 | */ | |
290 | ||
291 | void | |
292 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, | |
1b56ff3d | 293 | const char *passphrase, int do_encrypt) |
3c0ef626 | 294 | { |
295 | MD5_CTX md; | |
296 | u_char digest[16]; | |
297 | ||
298 | MD5_Init(&md); | |
299 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); | |
300 | MD5_Final(digest, &md); | |
301 | ||
1b56ff3d | 302 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
3c0ef626 | 303 | |
304 | memset(digest, 0, sizeof(digest)); | |
305 | memset(&md, 0, sizeof(md)); | |
306 | } | |
1e608e42 | 307 | |
1e608e42 | 308 | /* |
309 | * Exports an IV from the CipherContext required to export the key | |
310 | * state back from the unprivileged child to the privileged parent | |
311 | * process. | |
312 | */ | |
313 | ||
314 | int | |
416fd2a8 | 315 | cipher_get_keyiv_len(const CipherContext *cc) |
1e608e42 | 316 | { |
317 | Cipher *c = cc->cipher; | |
318 | int ivlen; | |
319 | ||
320 | if (c->number == SSH_CIPHER_3DES) | |
321 | ivlen = 24; | |
322 | else | |
323 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
324 | return (ivlen); | |
325 | } | |
326 | ||
327 | void | |
328 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
329 | { | |
330 | Cipher *c = cc->cipher; | |
1e608e42 | 331 | int evplen; |
332 | ||
333 | switch (c->number) { | |
34fee935 | 334 | case SSH_CIPHER_NONE: |
1e608e42 | 335 | case SSH_CIPHER_SSH2: |
336 | case SSH_CIPHER_DES: | |
337 | case SSH_CIPHER_BLOWFISH: | |
338 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
34fee935 | 339 | if (evplen <= 0) |
1e608e42 | 340 | return; |
34fee935 | 341 | if ((u_int)evplen != len) |
ff2d7a98 | 342 | fatal("%s: wrong iv length %d != %d", __func__, |
1e608e42 | 343 | evplen, len); |
e00da40d | 344 | #ifdef USE_BUILTIN_RIJNDAEL |
70791e56 | 345 | if (c->evptype == evp_rijndael) |
346 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
347 | else | |
ff2d7a98 | 348 | #endif |
70791e56 | 349 | if (c->evptype == evp_aes_128_ctr) |
350 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
351 | else | |
352 | memcpy(iv, cc->evp.iv, len); | |
353 | break; | |
354 | case SSH_CIPHER_3DES: | |
355 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
1e608e42 | 356 | break; |
1e608e42 | 357 | default: |
ff2d7a98 | 358 | fatal("%s: bad cipher %d", __func__, c->number); |
1e608e42 | 359 | } |
1e608e42 | 360 | } |
361 | ||
362 | void | |
363 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
364 | { | |
365 | Cipher *c = cc->cipher; | |
1e608e42 | 366 | int evplen = 0; |
367 | ||
368 | switch (c->number) { | |
34fee935 | 369 | case SSH_CIPHER_NONE: |
1e608e42 | 370 | case SSH_CIPHER_SSH2: |
371 | case SSH_CIPHER_DES: | |
372 | case SSH_CIPHER_BLOWFISH: | |
373 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
374 | if (evplen == 0) | |
375 | return; | |
e00da40d | 376 | #ifdef USE_BUILTIN_RIJNDAEL |
70791e56 | 377 | if (c->evptype == evp_rijndael) |
378 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
379 | else | |
ff2d7a98 | 380 | #endif |
70791e56 | 381 | if (c->evptype == evp_aes_128_ctr) |
382 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
383 | else | |
384 | memcpy(cc->evp.iv, iv, evplen); | |
385 | break; | |
386 | case SSH_CIPHER_3DES: | |
387 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
1e608e42 | 388 | break; |
1e608e42 | 389 | default: |
ff2d7a98 | 390 | fatal("%s: bad cipher %d", __func__, c->number); |
1e608e42 | 391 | } |
1e608e42 | 392 | } |
393 | ||
394 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
395 | #define EVP_X_STATE(evp) &(evp).c | |
396 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
397 | #else | |
398 | #define EVP_X_STATE(evp) (evp).cipher_data | |
399 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
400 | #endif | |
401 | ||
402 | int | |
416fd2a8 | 403 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
1e608e42 | 404 | { |
405 | Cipher *c = cc->cipher; | |
ff2d7a98 | 406 | int plen = 0; |
1e608e42 | 407 | |
416fd2a8 | 408 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
ff2d7a98 | 409 | plen = EVP_X_STATE_LEN(cc->evp); |
1e608e42 | 410 | if (dat == NULL) |
ff2d7a98 | 411 | return (plen); |
412 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
1e608e42 | 413 | } |
1e608e42 | 414 | return (plen); |
415 | } | |
416 | ||
417 | void | |
418 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
419 | { | |
420 | Cipher *c = cc->cipher; | |
421 | int plen; | |
422 | ||
416fd2a8 | 423 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
1e608e42 | 424 | plen = EVP_X_STATE_LEN(cc->evp); |
425 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
426 | } | |
427 | } |