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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" | |
38 | RCSID("$OpenBSD: cipher.c,v 1.47 2001/08/23 11:31:59 markus Exp $"); | |
39 | ||
40 | #include "xmalloc.h" | |
41 | #include "log.h" | |
42 | #include "cipher.h" | |
43 | ||
44 | #include <openssl/md5.h> | |
45 | ||
46 | /* no encryption */ | |
47 | static void | |
48 | none_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
49 | { | |
50 | } | |
51 | static void | |
52 | none_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
53 | { | |
54 | } | |
55 | static void | |
56 | none_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
57 | { | |
58 | memcpy(dest, src, len); | |
59 | } | |
60 | ||
61 | /* DES */ | |
62 | static void | |
63 | des_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
64 | { | |
65 | static int dowarn = 1; | |
66 | if (dowarn) { | |
67 | error("Warning: use of DES is strongly discouraged " | |
68 | "due to cryptographic weaknesses"); | |
69 | dowarn = 0; | |
70 | } | |
71 | des_set_key((void *)key, cc->u.des.key); | |
72 | } | |
73 | static void | |
74 | des_ssh1_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
75 | { | |
76 | memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv)); | |
77 | } | |
78 | static void | |
79 | des_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
80 | { | |
81 | des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv, | |
82 | DES_ENCRYPT); | |
83 | } | |
84 | static void | |
85 | des_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
86 | { | |
87 | des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv, | |
88 | DES_DECRYPT); | |
89 | } | |
90 | ||
91 | /* 3DES */ | |
92 | static void | |
93 | des3_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
94 | { | |
95 | des_set_key((void *) key, cc->u.des3.key1); | |
96 | des_set_key((void *) (key+8), cc->u.des3.key2); | |
97 | des_set_key((void *) (key+16), cc->u.des3.key3); | |
98 | } | |
99 | static void | |
100 | des3_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
101 | { | |
102 | memset(cc->u.des3.iv1, 0, sizeof(cc->u.des3.iv1)); | |
103 | memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2)); | |
104 | memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3)); | |
105 | if (iv == NULL) | |
106 | return; | |
107 | memcpy(cc->u.des3.iv3, (char *)iv, 8); | |
108 | } | |
109 | static void | |
110 | des3_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
111 | { | |
112 | des_ede3_cbc_encrypt(src, dest, len, | |
113 | cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3, | |
114 | &cc->u.des3.iv3, DES_ENCRYPT); | |
115 | } | |
116 | static void | |
117 | des3_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
118 | { | |
119 | des_ede3_cbc_encrypt(src, dest, len, | |
120 | cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3, | |
121 | &cc->u.des3.iv3, DES_DECRYPT); | |
122 | } | |
123 | ||
124 | /* | |
125 | * This is used by SSH1: | |
126 | * | |
127 | * What kind of triple DES are these 2 routines? | |
128 | * | |
129 | * Why is there a redundant initialization vector? | |
130 | * | |
131 | * If only iv3 was used, then, this would till effect have been | |
132 | * outer-cbc. However, there is also a private iv1 == iv2 which | |
133 | * perhaps makes differential analysis easier. On the other hand, the | |
134 | * private iv1 probably makes the CRC-32 attack ineffective. This is a | |
135 | * result of that there is no longer any known iv1 to use when | |
136 | * choosing the X block. | |
137 | */ | |
138 | static void | |
139 | des3_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
140 | { | |
141 | des_set_key((void *) key, cc->u.des3.key1); | |
142 | des_set_key((void *) (key+8), cc->u.des3.key2); | |
143 | if (keylen <= 16) | |
144 | des_set_key((void *) key, cc->u.des3.key3); | |
145 | else | |
146 | des_set_key((void *) (key+16), cc->u.des3.key3); | |
147 | } | |
148 | static void | |
149 | des3_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
150 | u_int len) | |
151 | { | |
152 | des_ncbc_encrypt(src, dest, len, cc->u.des3.key1, &cc->u.des3.iv1, | |
153 | DES_ENCRYPT); | |
154 | des_ncbc_encrypt(dest, dest, len, cc->u.des3.key2, &cc->u.des3.iv2, | |
155 | DES_DECRYPT); | |
156 | des_ncbc_encrypt(dest, dest, len, cc->u.des3.key3, &cc->u.des3.iv3, | |
157 | DES_ENCRYPT); | |
158 | } | |
159 | static void | |
160 | des3_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
161 | u_int len) | |
162 | { | |
163 | des_ncbc_encrypt(src, dest, len, cc->u.des3.key3, &cc->u.des3.iv3, | |
164 | DES_DECRYPT); | |
165 | des_ncbc_encrypt(dest, dest, len, cc->u.des3.key2, &cc->u.des3.iv2, | |
166 | DES_ENCRYPT); | |
167 | des_ncbc_encrypt(dest, dest, len, cc->u.des3.key1, &cc->u.des3.iv1, | |
168 | DES_DECRYPT); | |
169 | } | |
170 | ||
171 | /* Blowfish */ | |
172 | static void | |
173 | blowfish_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
174 | { | |
175 | BF_set_key(&cc->u.bf.key, keylen, (u_char *)key); | |
176 | } | |
177 | static void | |
178 | blowfish_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
179 | { | |
180 | if (iv == NULL) | |
181 | memset(cc->u.bf.iv, 0, 8); | |
182 | else | |
183 | memcpy(cc->u.bf.iv, (char *)iv, 8); | |
184 | } | |
185 | static void | |
186 | blowfish_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
187 | u_int len) | |
188 | { | |
189 | BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv, | |
190 | BF_ENCRYPT); | |
191 | } | |
192 | static void | |
193 | blowfish_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
194 | u_int len) | |
195 | { | |
196 | BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv, | |
197 | BF_DECRYPT); | |
198 | } | |
199 | ||
200 | /* | |
201 | * SSH1 uses a variation on Blowfish, all bytes must be swapped before | |
202 | * and after encryption/decryption. Thus the swap_bytes stuff (yuk). | |
203 | */ | |
204 | static void | |
205 | swap_bytes(const u_char *src, u_char *dst, int n) | |
206 | { | |
207 | char c[4]; | |
208 | ||
209 | /* Process 4 bytes every lap. */ | |
210 | for (n = n / 4; n > 0; n--) { | |
211 | c[3] = *src++; | |
212 | c[2] = *src++; | |
213 | c[1] = *src++; | |
214 | c[0] = *src++; | |
215 | ||
216 | *dst++ = c[0]; | |
217 | *dst++ = c[1]; | |
218 | *dst++ = c[2]; | |
219 | *dst++ = c[3]; | |
220 | } | |
221 | } | |
222 | ||
223 | static void | |
224 | blowfish_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
225 | u_int len) | |
226 | { | |
227 | swap_bytes(src, dest, len); | |
228 | BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv, | |
229 | BF_ENCRYPT); | |
230 | swap_bytes(dest, dest, len); | |
231 | } | |
232 | static void | |
233 | blowfish_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
234 | u_int len) | |
235 | { | |
236 | swap_bytes(src, dest, len); | |
237 | BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv, | |
238 | BF_DECRYPT); | |
239 | swap_bytes(dest, dest, len); | |
240 | } | |
241 | ||
242 | /* alleged rc4 */ | |
243 | static void | |
244 | arcfour_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
245 | { | |
246 | RC4_set_key(&cc->u.rc4, keylen, (u_char *)key); | |
247 | } | |
248 | static void | |
249 | arcfour_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
250 | { | |
251 | RC4(&cc->u.rc4, len, (u_char *)src, dest); | |
252 | } | |
253 | ||
254 | /* CAST */ | |
255 | static void | |
256 | cast_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
257 | { | |
258 | CAST_set_key(&cc->u.cast.key, keylen, (u_char *) key); | |
259 | } | |
260 | static void | |
261 | cast_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
262 | { | |
263 | if (iv == NULL) | |
264 | fatal("no IV for %s.", cc->cipher->name); | |
265 | memcpy(cc->u.cast.iv, (char *)iv, 8); | |
266 | } | |
267 | static void | |
268 | cast_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
269 | { | |
270 | CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv, | |
271 | CAST_ENCRYPT); | |
272 | } | |
273 | static void | |
274 | cast_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
275 | { | |
276 | CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv, | |
277 | CAST_DECRYPT); | |
278 | } | |
279 | ||
280 | /* RIJNDAEL */ | |
281 | ||
282 | #define RIJNDAEL_BLOCKSIZE 16 | |
283 | static void | |
284 | rijndael_setkey(CipherContext *cc, const u_char *key, u_int keylen) | |
285 | { | |
286 | rijndael_set_key(&cc->u.rijndael.enc, (char *)key, 8*keylen, 1); | |
287 | rijndael_set_key(&cc->u.rijndael.dec, (char *)key, 8*keylen, 0); | |
288 | } | |
289 | static void | |
290 | rijndael_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) | |
291 | { | |
292 | if (iv == NULL || ivlen != RIJNDAEL_BLOCKSIZE) | |
293 | fatal("bad/no IV for %s.", cc->cipher->name); | |
294 | memcpy(cc->u.rijndael.iv, iv, RIJNDAEL_BLOCKSIZE); | |
295 | } | |
296 | static void | |
297 | rijndael_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
298 | u_int len) | |
299 | { | |
300 | rijndael_ctx *ctx = &cc->u.rijndael.enc; | |
301 | u_char *iv = cc->u.rijndael.iv; | |
302 | u_char in[RIJNDAEL_BLOCKSIZE]; | |
303 | u_char *cprev, *cnow, *plain; | |
304 | int i, j, blocks = len / RIJNDAEL_BLOCKSIZE; | |
305 | ||
306 | if (len == 0) | |
307 | return; | |
308 | if (len % RIJNDAEL_BLOCKSIZE) | |
309 | fatal("rijndael_cbc_encrypt: bad len %d", len); | |
310 | cnow = dest; | |
311 | plain = (u_char *) src; | |
312 | cprev = iv; | |
313 | for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE, | |
314 | cnow+=RIJNDAEL_BLOCKSIZE) { | |
315 | for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++) | |
316 | in[j] = plain[j] ^ cprev[j]; | |
317 | rijndael_encrypt(ctx, in, cnow); | |
318 | cprev = cnow; | |
319 | } | |
320 | memcpy(iv, cprev, RIJNDAEL_BLOCKSIZE); | |
321 | } | |
322 | static void | |
323 | rijndael_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, | |
324 | u_int len) | |
325 | { | |
326 | rijndael_ctx *ctx = &cc->u.rijndael.dec; | |
327 | u_char *iv = cc->u.rijndael.iv; | |
328 | u_char ivsaved[RIJNDAEL_BLOCKSIZE]; | |
329 | u_char *cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE); | |
330 | u_char *plain = dest+len-RIJNDAEL_BLOCKSIZE; | |
331 | u_char *ivp; | |
332 | int i, j, blocks = len / RIJNDAEL_BLOCKSIZE; | |
333 | ||
334 | if (len == 0) | |
335 | return; | |
336 | if (len % RIJNDAEL_BLOCKSIZE) | |
337 | fatal("rijndael_cbc_decrypt: bad len %d", len); | |
338 | memcpy(ivsaved, cnow, RIJNDAEL_BLOCKSIZE); | |
339 | for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE, | |
340 | plain-=RIJNDAEL_BLOCKSIZE) { | |
341 | rijndael_decrypt(ctx, cnow, plain); | |
342 | ivp = (i == 1) ? iv : cnow-RIJNDAEL_BLOCKSIZE; | |
343 | for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++) | |
344 | plain[j] ^= ivp[j]; | |
345 | } | |
346 | memcpy(iv, ivsaved, RIJNDAEL_BLOCKSIZE); | |
347 | } | |
348 | ||
349 | Cipher ciphers[] = { | |
350 | { "none", | |
351 | SSH_CIPHER_NONE, 8, 0, | |
352 | none_setkey, none_setiv, | |
353 | none_crypt, none_crypt }, | |
354 | { "des", | |
355 | SSH_CIPHER_DES, 8, 8, | |
356 | des_ssh1_setkey, des_ssh1_setiv, | |
357 | des_ssh1_encrypt, des_ssh1_decrypt }, | |
358 | { "3des", | |
359 | SSH_CIPHER_3DES, 8, 16, | |
360 | des3_ssh1_setkey, des3_setiv, | |
361 | des3_ssh1_encrypt, des3_ssh1_decrypt }, | |
362 | { "blowfish", | |
363 | SSH_CIPHER_BLOWFISH, 8, 16, | |
364 | blowfish_setkey, blowfish_setiv, | |
365 | blowfish_ssh1_encrypt, blowfish_ssh1_decrypt }, | |
366 | ||
367 | { "3des-cbc", | |
368 | SSH_CIPHER_SSH2, 8, 24, | |
369 | des3_setkey, des3_setiv, | |
370 | des3_cbc_encrypt, des3_cbc_decrypt }, | |
371 | { "blowfish-cbc", | |
372 | SSH_CIPHER_SSH2, 8, 16, | |
373 | blowfish_setkey, blowfish_setiv, | |
374 | blowfish_cbc_encrypt, blowfish_cbc_decrypt }, | |
375 | { "cast128-cbc", | |
376 | SSH_CIPHER_SSH2, 8, 16, | |
377 | cast_setkey, cast_setiv, | |
378 | cast_cbc_encrypt, cast_cbc_decrypt }, | |
379 | { "arcfour", | |
380 | SSH_CIPHER_SSH2, 8, 16, | |
381 | arcfour_setkey, none_setiv, | |
382 | arcfour_crypt, arcfour_crypt }, | |
383 | { "aes128-cbc", | |
384 | SSH_CIPHER_SSH2, 16, 16, | |
385 | rijndael_setkey, rijndael_setiv, | |
386 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
387 | { "aes192-cbc", | |
388 | SSH_CIPHER_SSH2, 16, 24, | |
389 | rijndael_setkey, rijndael_setiv, | |
390 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
391 | { "aes256-cbc", | |
392 | SSH_CIPHER_SSH2, 16, 32, | |
393 | rijndael_setkey, rijndael_setiv, | |
394 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
395 | { "rijndael128-cbc", | |
396 | SSH_CIPHER_SSH2, 16, 16, | |
397 | rijndael_setkey, rijndael_setiv, | |
398 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
399 | { "rijndael192-cbc", | |
400 | SSH_CIPHER_SSH2, 16, 24, | |
401 | rijndael_setkey, rijndael_setiv, | |
402 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
403 | { "rijndael256-cbc", | |
404 | SSH_CIPHER_SSH2, 16, 32, | |
405 | rijndael_setkey, rijndael_setiv, | |
406 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
407 | { "rijndael-cbc@lysator.liu.se", | |
408 | SSH_CIPHER_SSH2, 16, 32, | |
409 | rijndael_setkey, rijndael_setiv, | |
410 | rijndael_cbc_encrypt, rijndael_cbc_decrypt }, | |
411 | { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL } | |
412 | }; | |
413 | ||
414 | /*--*/ | |
415 | ||
416 | u_int | |
417 | cipher_mask_ssh1(int client) | |
418 | { | |
419 | u_int mask = 0; | |
420 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ | |
421 | mask |= 1 << SSH_CIPHER_BLOWFISH; | |
422 | if (client) { | |
423 | mask |= 1 << SSH_CIPHER_DES; | |
424 | } | |
425 | return mask; | |
426 | } | |
427 | ||
428 | Cipher * | |
429 | cipher_by_name(const char *name) | |
430 | { | |
431 | Cipher *c; | |
432 | for (c = ciphers; c->name != NULL; c++) | |
433 | if (strcasecmp(c->name, name) == 0) | |
434 | return c; | |
435 | return NULL; | |
436 | } | |
437 | ||
438 | Cipher * | |
439 | cipher_by_number(int id) | |
440 | { | |
441 | Cipher *c; | |
442 | for (c = ciphers; c->name != NULL; c++) | |
443 | if (c->number == id) | |
444 | return c; | |
445 | return NULL; | |
446 | } | |
447 | ||
448 | #define CIPHER_SEP "," | |
449 | int | |
450 | ciphers_valid(const char *names) | |
451 | { | |
452 | Cipher *c; | |
453 | char *ciphers, *cp; | |
454 | char *p; | |
455 | ||
456 | if (names == NULL || strcmp(names, "") == 0) | |
457 | return 0; | |
458 | ciphers = cp = xstrdup(names); | |
459 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; | |
460 | (p = strsep(&cp, CIPHER_SEP))) { | |
461 | c = cipher_by_name(p); | |
462 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
463 | debug("bad cipher %s [%s]", p, names); | |
464 | xfree(ciphers); | |
465 | return 0; | |
466 | } else { | |
467 | debug3("cipher ok: %s [%s]", p, names); | |
468 | } | |
469 | } | |
470 | debug3("ciphers ok: [%s]", names); | |
471 | xfree(ciphers); | |
472 | return 1; | |
473 | } | |
474 | ||
475 | /* | |
476 | * Parses the name of the cipher. Returns the number of the corresponding | |
477 | * cipher, or -1 on error. | |
478 | */ | |
479 | ||
480 | int | |
481 | cipher_number(const char *name) | |
482 | { | |
483 | Cipher *c; | |
484 | if (name == NULL) | |
485 | return -1; | |
486 | c = cipher_by_name(name); | |
487 | return (c==NULL) ? -1 : c->number; | |
488 | } | |
489 | ||
490 | char * | |
491 | cipher_name(int id) | |
492 | { | |
493 | Cipher *c = cipher_by_number(id); | |
494 | return (c==NULL) ? "<unknown>" : c->name; | |
495 | } | |
496 | ||
497 | void | |
498 | cipher_init(CipherContext *cc, Cipher *cipher, | |
499 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen) | |
500 | { | |
501 | if (keylen < cipher->key_len) | |
502 | fatal("cipher_init: key length %d is insufficient for %s.", | |
503 | keylen, cipher->name); | |
504 | if (iv != NULL && ivlen < cipher->block_size) | |
505 | fatal("cipher_init: iv length %d is insufficient for %s.", | |
506 | ivlen, cipher->name); | |
507 | cc->cipher = cipher; | |
508 | cipher->setkey(cc, key, keylen); | |
509 | cipher->setiv(cc, iv, ivlen); | |
510 | } | |
511 | ||
512 | void | |
513 | cipher_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
514 | { | |
515 | if (len % cc->cipher->block_size) | |
516 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
517 | cc->cipher->encrypt(cc, dest, src, len); | |
518 | } | |
519 | ||
520 | void | |
521 | cipher_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) | |
522 | { | |
523 | if (len % cc->cipher->block_size) | |
524 | fatal("cipher_decrypt: bad ciphertext length %d", len); | |
525 | cc->cipher->decrypt(cc, dest, src, len); | |
526 | } | |
527 | ||
528 | /* | |
529 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
530 | * passphrase and using the resulting 16 bytes as the key. | |
531 | */ | |
532 | ||
533 | void | |
534 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, | |
535 | const char *passphrase) | |
536 | { | |
537 | MD5_CTX md; | |
538 | u_char digest[16]; | |
539 | ||
540 | MD5_Init(&md); | |
541 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); | |
542 | MD5_Final(digest, &md); | |
543 | ||
544 | cipher_init(cc, cipher, digest, 16, NULL, 0); | |
545 | ||
546 | memset(digest, 0, sizeof(digest)); | |
547 | memset(&md, 0, sizeof(md)); | |
548 | } |