chiark / gitweb /
Incopatible protocol fix! Include message type code under MAC tag to prevent
[tripe] / keyset.c
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410c8acf 1/* -*-c-*-
2 *
7ed14135 3 * $Id: keyset.c,v 1.8 2003/07/13 11:19:49 mdw Exp $
410c8acf 4 *
5 * Handling of symmetric keysets
6 *
7 * (c) 2001 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of Trivial IP Encryption (TrIPE).
13 *
14 * TrIPE is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
18 *
19 * TrIPE is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with TrIPE; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27 */
28
29/*----- Revision history --------------------------------------------------*
30 *
31 * $Log: keyset.c,v $
7ed14135 32 * Revision 1.8 2003/07/13 11:19:49 mdw
33 * Incopatible protocol fix! Include message type code under MAC tag to prevent
34 * cut-and-paste from key-exchange messages to general packet transport.
35 *
e945d6e4 36 * Revision 1.7 2003/05/17 11:00:47 mdw
37 * Don't make scary messages just because one key didn't work on a message:
38 * only be frightened if they all fail. Set initial keyset refcount
39 * correctly.
40 *
9466fafa 41 * Revision 1.6 2003/04/06 10:26:35 mdw
42 * Report peer name on decrypt errors.
43 *
59d670e7 44 * Revision 1.5 2001/06/19 22:07:43 mdw
45 * Change the encrypted packet format to be non-malleable.
46 *
d132c651 47 * Revision 1.4 2001/06/16 14:06:40 mdw
48 * Quantify collision probabilities for the stated data volume bounds.
49 *
426c0bc6 50 * Revision 1.3 2001/02/16 21:39:55 mdw
51 * Major overhaul. Separate functions for manipulating keysets from
52 * functions for manipulating keyset lists. Introduce a concept of
53 * listening-only keys.
54 *
09585a65 55 * Revision 1.2 2001/02/05 19:53:23 mdw
56 * Add sequence number protection.
57 *
410c8acf 58 * Revision 1.1 2001/02/03 20:26:37 mdw
59 * Initial checkin.
60 *
61 */
62
63/*----- Header files ------------------------------------------------------*/
64
65#include "tripe.h"
66
67/*----- Tunable parameters ------------------------------------------------*/
68
d132c651 69/* --- Note on size limits --- *
70 *
71 * For a 64-bit block cipher (e.g., Blowfish), the probability of a collision
72 * occurring after 32 MB is less than %$2^{-21}$%, and the probability of a
73 * collision occurring after 64 MB is less than %$2^{-19}$%.
74 */
75
426c0bc6 76#define T_EXP MIN(60) /* Expiry time for a key */
77#define T_REGEN MIN(45) /* Regeneration time for a key */
78#define SZ_EXP MEG(64) /* Expiry data size for a key */
79#define SZ_REGEN MEG(32) /* Data size threshold for regen */
410c8acf 80
81/*----- Handy macros ------------------------------------------------------*/
82
83#define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now)
84
426c0bc6 85/*----- Low-level packet encryption and decryption ------------------------*/
410c8acf 86
59d670e7 87/* --- Encrypted data format --- *
88 *
7ed14135 89 * Let %$p_i$% be the %$i$%-th plaintext message, with type %$t$%. We first
90 * compute
59d670e7 91 *
92 * %$c_i = \mathcal{E}\textrm{-CBC}_{K_{\text{E}}}(p_i)$%
93 *
94 * as the CBC-ciphertext of %$p_i$%, and then
95 *
7ed14135 96 * %$\sigma_i = \mathcal{T}_{K_{\text{M}}}(t, i, c_i)$%
59d670e7 97 *
98 * as a MAC on the %%\emph{ciphertext}%%. The message sent is then the pair
99 * %$(\sigma_i, c_i)$%. This construction is provably secure in the NM-CCA
100 * sense (assuming that the cipher is IND-CPA, and the MAC is SUF-CMA)
101 * [Bellare and Namprempre].
102 *
103 * This also ensures that, assuming the key is good, we have a secure channel
104 * [Krawczyk]. Actually, [Krawczyk] shows that, if the cipher is either a
105 * simple stream cipher or a block cipher in CBC mode, we can use the MAC-
106 * then-encrypt scheme and still have a secure channel. However, I like the
107 * NM-CCA guarantee from [Bellare and Namprempre]. I'm less worried about
108 * the Horton Principle [Wagner and Schneier].
109 */
110
426c0bc6 111/* --- @doencrypt@ --- *
410c8acf 112 *
426c0bc6 113 * Arguments: @keyset *ks@ = pointer to keyset to use
7ed14135 114 * @unsigned ty@ = type of message this is
426c0bc6 115 * @buf *b@ = pointer to an input buffer
116 * @buf *bb@ = pointer to an output buffer
410c8acf 117 *
426c0bc6 118 * Returns: Zero if OK, nonzero if a new key is required.
410c8acf 119 *
426c0bc6 120 * Use: Encrypts a message with the given key. We assume that the
121 * keyset is OK to use.
410c8acf 122 */
123
7ed14135 124static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
410c8acf 125{
426c0bc6 126 ghash *h;
127 gcipher *c;
426c0bc6 128 const octet *p = BCUR(b);
129 size_t sz = BLEFT(b);
59d670e7 130 octet *qmac, *qseq, *qiv, *qpk;
426c0bc6 131 uint32 oseq;
132 size_t osz, nsz;
7ed14135 133 octet t[4];
426c0bc6 134 int rc = 0;
135
136 /* --- Allocate the required buffer space --- */
137
138 c = ks->cout;
59d670e7 139 if (buf_ensure(bb, MACSZ + SEQSZ + IVSZ + sz))
426c0bc6 140 return (0); /* Caution! */
59d670e7 141 qmac = BCUR(bb); qseq = qmac + MACSZ; qiv = qseq + SEQSZ; qpk = qiv + IVSZ;
142 BSTEP(bb, MACSZ + SEQSZ + IVSZ + sz);
7ed14135 143 STORE32(t, ty);
426c0bc6 144
59d670e7 145 /* --- Encrypt the packet --- */
426c0bc6 146
147 oseq = ks->oseq++; STORE32(qseq, oseq);
59d670e7 148 rand_get(RAND_GLOBAL, qiv, IVSZ);
149 c->ops->setiv(c, qiv);
150 c->ops->encrypt(c, p, qpk, sz);
426c0bc6 151 IF_TRACING(T_KEYSET, {
152 trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u",
153 (unsigned long)oseq, ks->seq);
59d670e7 154 trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz);
426c0bc6 155 })
59d670e7 156
157 /* --- Now compute the MAC --- */
158
159 h = ks->mout->ops->init(ks->mout);
7ed14135 160 h->ops->hash(h, t, sizeof(t));
59d670e7 161 h->ops->hash(h, qseq, SEQSZ + IVSZ + sz);
162 memcpy(qmac, h->ops->done(h, 0), MACSZ);
163 h->ops->destroy(h);
426c0bc6 164 IF_TRACING(T_KEYSET, {
59d670e7 165 trace_block(T_CRYPTO, "crypto: computed MAC", qmac, MACSZ);
426c0bc6 166 })
167
168 /* --- Deduct the packet size from the key's data life --- */
169
170 osz = ks->sz_exp;
171 if (osz > sz)
172 nsz = osz - sz;
173 else
174 nsz = 0;
175 if (osz >= SZ_REGEN && nsz < SZ_REGEN) {
176 T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- "
177 "forcing exchange", ks->seq); )
178 rc = -1;
179 }
180 ks->sz_exp = nsz;
181 return (rc);
410c8acf 182}
183
426c0bc6 184/* --- @dodecrypt@ --- *
410c8acf 185 *
426c0bc6 186 * Arguments: @keyset *ks@ = pointer to keyset to use
7ed14135 187 * @unsigned ty@ = expected type code
426c0bc6 188 * @buf *b@ = pointer to an input buffer
189 * @buf *bb@ = pointer to an output buffer
190 * @uint32 *seq@ = where to store the sequence number
410c8acf 191 *
426c0bc6 192 * Returns: Zero if OK, nonzero if it failed.
410c8acf 193 *
426c0bc6 194 * Use: Attempts to decrypt a message with the given key. No other
195 * checking (e.g., sequence number checks) is performed. We
196 * assume that the keyset is OK to use, and that there is
197 * sufficient output buffer space reserved. If the decryption
198 * is successful, the buffer pointer is moved past the decrypted
199 * packet, and the packet's sequence number is stored in @*seq@.
410c8acf 200 */
201
7ed14135 202static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq)
410c8acf 203{
59d670e7 204 const octet *pmac, *piv, *pseq, *ppk;
426c0bc6 205 size_t psz = BLEFT(b);
206 size_t sz;
207 octet *q = BCUR(bb);
208 ghash *h;
209 gcipher *c = ks->cin;
210 size_t ivsz = c->ops->c->blksz;
211 octet *mac;
212 int eq;
7ed14135 213 octet t[4];
426c0bc6 214
215 /* --- Break up the packet into its components --- */
216
217 if (psz < ivsz + 4) {
218 T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); )
219 return (-1);
410c8acf 220 }
59d670e7 221 sz = psz - IVSZ - SEQSZ - MACSZ;
222 pmac = BCUR(b); pseq = pmac + MACSZ; piv = pseq + SEQSZ; ppk = piv + IVSZ;
7ed14135 223 STORE32(t, ty);
426c0bc6 224
59d670e7 225 /* --- Verify the MAC on the packet --- */
426c0bc6 226
426c0bc6 227 h = ks->min->ops->init(ks->min);
7ed14135 228 h->ops->hash(h, t, sizeof(t));
59d670e7 229 h->ops->hash(h, pseq, SEQSZ + IVSZ + sz);
426c0bc6 230 mac = h->ops->done(h, 0);
59d670e7 231 eq = !memcmp(mac, pmac, MACSZ);
426c0bc6 232 IF_TRACING(T_KEYSET, {
233 trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq);
59d670e7 234 trace_block(T_CRYPTO, "crypto: computed MAC", mac, MACSZ);
426c0bc6 235 })
236 h->ops->destroy(h);
237 if (!eq) {
238 IF_TRACING(T_KEYSET, {
e945d6e4 239 trace(T_KEYSET, "keyset: incorrect MAC: decryption failed");
59d670e7 240 trace_block(T_CRYPTO, "crypto: expected MAC", pmac, MACSZ);
426c0bc6 241 })
242 return (-1);
243 }
59d670e7 244
245 /* --- Decrypt the packet --- */
246
247 c->ops->setiv(c, piv);
248 c->ops->decrypt(c, ppk, q, sz);
426c0bc6 249 if (seq)
250 *seq = LOAD32(pseq);
251 IF_TRACING(T_KEYSET, {
252 trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)",
253 (unsigned long)LOAD32(pseq));
254 trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz);
255 })
256 BSTEP(bb, sz);
257 return (0);
410c8acf 258}
259
426c0bc6 260/* --- @dosequence@ --- *
410c8acf 261 *
426c0bc6 262 * Arguments: @keyset *ks@ = pointer to a keyset
263 * @uint32 seq@ = a sequence number from a packet
410c8acf 264 *
426c0bc6 265 * Returns: Zero if the sequence number is OK, nonzero if it's not.
410c8acf 266 *
426c0bc6 267 * Use: Checks a sequence number. The data in the keyset which keeps
268 * track of valid sequence numbers is updated if the sequence
269 * number given is good. It's assumed that the sequence number
270 * has already been checked for authenticity.
410c8acf 271 */
272
426c0bc6 273static int dosequence(keyset *ks, uint32 seq)
410c8acf 274{
426c0bc6 275 uint32 seqbit;
276 uint32 n;
410c8acf 277
426c0bc6 278 if (seq < ks->iseq) {
279 a_warn("received packet has old sequence number (possible replay)");
280 return (-1);
410c8acf 281 }
426c0bc6 282 if (seq >= ks->iseq + KS_SEQWINSZ) {
283 n = seq - (ks->iseq + KS_SEQWINSZ - 1);
284 if (n < KS_SEQWINSZ)
285 ks->iwin >>= n;
286 else
287 ks->iwin = 0;
288 ks->iseq += n;
289 }
290 seqbit = 1 << (seq - ks->iseq);
291 if (ks->iwin & seqbit) {
292 a_warn("received packet repeats old sequence number");
293 return (-1);
294 }
295 ks->iwin |= seqbit;
296 return (0);
297}
298
299/*----- Operations on a single keyset -------------------------------------*/
300
301/* --- @ks_drop@ --- *
302 *
303 * Arguments: @keyset *ks@ = pointer to a keyset
304 *
305 * Returns: ---
306 *
307 * Use: Decrements a keyset's reference counter. If the counter hits
308 * zero, the keyset is freed.
309 */
310
311void ks_drop(keyset *ks)
312{
313 if (--ks->ref)
314 return;
315 ks->cin->ops->destroy(ks->cin);
316 ks->cout->ops->destroy(ks->cout);
317 ks->min->ops->destroy(ks->min);
318 ks->mout->ops->destroy(ks->mout);
319 DESTROY(ks);
410c8acf 320}
321
322/* --- @ks_gen@ --- *
323 *
426c0bc6 324 * Arguments: @const void *k@ = pointer to key material
325 * @size_t x, y, z@ = offsets into key material (see below)
9466fafa 326 * @peer *p@ = pointer to peer information
410c8acf 327 *
426c0bc6 328 * Returns: A pointer to the new keyset.
410c8acf 329 *
426c0bc6 330 * Use: Derives a new keyset from the given key material. The
331 * offsets @x@, @y@ and @z@ separate the key material into three
332 * parts. Between the @k@ and @k + x@ is `my' contribution to
333 * the key material; between @k + x@ and @k + y@ is `your'
334 * contribution; and between @k + y@ and @k + z@ is a shared
335 * value we made together. These are used to construct two
336 * pairs of symmetric keys. Each pair consists of an encryption
337 * key and a message authentication key. One pair is used for
338 * outgoing messages, the other for incoming messages.
339 *
340 * The new key is marked so that it won't be selected for output
341 * by @ksl_encrypt@. You can still encrypt data with it by
342 * calling @ks_encrypt@ directly.
410c8acf 343 */
344
9466fafa 345keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
410c8acf 346{
426c0bc6 347 HASH_CTX h;
348 octet buf[HASHSZ];
410c8acf 349 keyset *ks = CREATE(keyset);
350 time_t now = time(0);
9466fafa 351 const octet *pp = k;
410c8acf 352 T( static unsigned seq = 0; )
353
354 T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); )
355
426c0bc6 356 /* --- Construct the various keys --- *
357 *
358 * This is done with macros, because it's quite tedious.
359 */
360
9466fafa 361#define MINE HASH(&h, pp, x)
362#define YOURS HASH(&h, pp + x, y - x)
363#define OURS HASH(&h, pp + y, z - y)
426c0bc6 364
365#define IN MINE; YOURS; OURS
366#define OUT YOURS; MINE; OURS
367#define STR_IN "incoming"
368#define STR_OUT "outgoing"
369
370#define GETHASH(str, dir) do { \
371 HASH_INIT(&h); \
372 HASH_STRING(&h, "tripe-" str); \
373 dir; \
374 HASH_DONE(&h, buf); \
410c8acf 375 IF_TRACING(T_KEYSET, { \
426c0bc6 376 trace_block(T_CRYPTO, "crypto: " STR_##dir " key " str, \
377 buf, sizeof(buf)); \
410c8acf 378 }) \
379} while (0)
380
426c0bc6 381 GETHASH("encryption", IN); ks->cin = CIPHER->init(buf, sizeof(buf));
382 GETHASH("integrity", IN); ks->min = MAC->key(buf, sizeof(buf));
383 GETHASH("encryption", OUT); ks->cout = CIPHER->init(buf, sizeof(buf));
384 GETHASH("integrity", OUT); ks->mout = MAC->key(buf, sizeof(buf));
385
386#undef MINE
387#undef YOURS
388#undef OURS
389#undef IN
390#undef OUT
391#undef STR_IN
392#undef STR_OUT
410c8acf 393#undef GETHASH
394
395 T( ks->seq = seq++; )
e945d6e4 396 ks->ref = 1;
426c0bc6 397 ks->t_exp = now + T_EXP;
398 ks->sz_exp = SZ_EXP;
09585a65 399 ks->oseq = ks->iseq = 0;
400 ks->iwin = 0;
426c0bc6 401 ks->next = 0;
9466fafa 402 ks->p = p;
426c0bc6 403 ks->f = KSF_LISTEN;
410c8acf 404 BURN(buf);
426c0bc6 405 return (ks);
406}
407
408/* --- @ks_tregen@ --- *
409 *
410 * Arguments: @keyset *ks@ = pointer to a keyset
411 *
412 * Returns: The time at which moves ought to be made to replace this key.
413 */
414
415time_t ks_tregen(keyset *ks) { return (ks->t_exp - T_EXP + T_REGEN); }
416
417/* --- @ks_activate@ --- *
418 *
419 * Arguments: @keyset *ks@ = pointer to a keyset
420 *
421 * Returns: ---
422 *
423 * Use: Activates a keyset, so that it can be used for encrypting
424 * outgoing messages.
425 */
426
427void ks_activate(keyset *ks)
428{
429 if (ks->f & KSF_LISTEN) {
430 T( trace(T_KEYSET, "keyset: activating keyset %u", ks->seq); )
431 ks->f &= ~KSF_LISTEN;
432 }
410c8acf 433}
434
435/* --- @ks_encrypt@ --- *
436 *
426c0bc6 437 * Arguments: @keyset *ks@ = pointer to a keyset
7ed14135 438 * @unsigned ty@ = message type
426c0bc6 439 * @buf *b@ = pointer to input buffer
440 * @buf *bb@ = pointer to output buffer
441 *
442 * Returns: Zero if OK, nonzero if the key needs replacing. If the
443 * encryption failed, the output buffer is broken and zero is
444 * returned.
445 *
446 * Use: Encrypts a block of data using the key. Note that the `key
447 * ought to be replaced' notification is only ever given once
448 * for each key. Also note that this call forces a keyset to be
449 * used even if it's marked as not for data output.
450 */
451
7ed14135 452int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
426c0bc6 453{
454 time_t now = time(0);
455
456 if (!KEYOK(ks, now)) {
457 buf_break(bb);
458 return (0);
459 }
7ed14135 460 return (doencrypt(ks, ty, b, bb));
426c0bc6 461}
462
463/* --- @ks_decrypt@ --- *
464 *
465 * Arguments: @keyset *ks@ = pointer to a keyset
7ed14135 466 * @unsigned ty@ = expected type code
426c0bc6 467 * @buf *b@ = pointer to an input buffer
468 * @buf *bb@ = pointer to an output buffer
469 *
470 * Returns: Zero on success, or nonzero if there was some problem.
471 *
472 * Use: Attempts to decrypt a message using a given key. Note that
473 * requesting decryption with a key directly won't clear a
474 * marking that it's not for encryption.
475 */
476
7ed14135 477int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
426c0bc6 478{
479 time_t now = time(0);
480 uint32 seq;
481
482 if (!KEYOK(ks, now) ||
483 buf_ensure(bb, BLEN(b)) ||
7ed14135 484 dodecrypt(ks, ty, b, bb, &seq) ||
426c0bc6 485 dosequence(ks, seq))
486 return (-1);
487 return (0);
488}
489
490/*----- Keyset list handling ----------------------------------------------*/
491
492/* --- @ksl_free@ --- *
493 *
494 * Arguments: @keyset **ksroot@ = pointer to keyset list head
495 *
496 * Returns: ---
497 *
498 * Use: Frees (releases references to) all of the keys in a keyset.
499 */
500
501void ksl_free(keyset **ksroot)
502{
503 keyset *ks, *ksn;
504 for (ks = *ksroot; ks; ks = ksn) {
505 ksn = ks->next;
506 ks->f &= ~KSF_LINK;
507 ks_drop(ks);
508 }
509}
510
511/* --- @ksl_link@ --- *
512 *
513 * Arguments: @keyset **ksroot@ = pointer to keyset list head
514 * @keyset *ks@ = pointer to a keyset
515 *
516 * Returns: ---
517 *
518 * Use: Links a keyset into a list. A keyset can only be on one list
519 * at a time. Bad things happen otherwise.
520 */
521
522void ksl_link(keyset **ksroot, keyset *ks)
523{
524 assert(!(ks->f & KSF_LINK));
525 ks->next = *ksroot;
526 *ksroot = ks;
527 ks->f |= KSF_LINK;
528 ks->ref++;
529}
530
531/* --- @ksl_prune@ --- *
532 *
533 * Arguments: @keyset **ksroot@ = pointer to keyset list head
534 *
535 * Returns: ---
536 *
537 * Use: Prunes the keyset list by removing keys which mustn't be used
538 * any more.
539 */
540
541void ksl_prune(keyset **ksroot)
542{
543 time_t now = time(0);
544
545 while (*ksroot) {
546 keyset *ks = *ksroot;
547
548 if (ks->t_exp <= now) {
549 T( trace(T_KEYSET, "keyset: expiring keyset %u (time limit reached)",
550 ks->seq); )
551 goto kill;
552 } else if (ks->sz_exp == 0) {
553 T( trace(T_KEYSET, "keyset: expiring keyset %u (data limit reached)",
554 ks->seq); )
555 goto kill;
556 } else {
557 ksroot = &ks->next;
558 continue;
559 }
560
561 kill:
562 *ksroot = ks->next;
563 ks->f &= ~KSF_LINK;
564 ks_drop(ks);
565 }
566}
567
568/* --- @ksl_encrypt@ --- *
569 *
410c8acf 570 * Arguments: @keyset **ksroot@ = pointer to keyset list head
7ed14135 571 * @unsigned ty@ = message type
410c8acf 572 * @buf *b@ = pointer to input buffer
573 * @buf *bb@ = pointer to output buffer
574 *
575 * Returns: Nonzero if a new key is needed.
576 *
577 * Use: Encrypts a packet.
578 */
579
7ed14135 580int ksl_encrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb)
410c8acf 581{
582 time_t now = time(0);
426c0bc6 583 keyset *ks = *ksroot;
410c8acf 584
410c8acf 585 for (;;) {
586 if (!ks) {
426c0bc6 587 T( trace(T_KEYSET, "keyset: no suitable keysets found"); )
410c8acf 588 buf_break(bb);
589 return (-1);
590 }
426c0bc6 591 if (KEYOK(ks, now) && !(ks->f & KSF_LISTEN))
410c8acf 592 break;
593 ks = ks->next;
594 }
595
7ed14135 596 return (doencrypt(ks, ty, b, bb));
410c8acf 597}
598
426c0bc6 599/* --- @ksl_decrypt@ --- *
410c8acf 600 *
601 * Arguments: @keyset **ksroot@ = pointer to keyset list head
7ed14135 602 * @unsigned ty@ = expected type code
410c8acf 603 * @buf *b@ = pointer to input buffer
604 * @buf *bb@ = pointer to output buffer
605 *
606 * Returns: Nonzero if the packet couldn't be decrypted.
607 *
608 * Use: Decrypts a packet.
609 */
610
7ed14135 611int ksl_decrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb)
410c8acf 612{
613 time_t now = time(0);
410c8acf 614 keyset *ks;
426c0bc6 615 uint32 seq;
410c8acf 616
426c0bc6 617 if (buf_ensure(bb, BLEN(b)))
410c8acf 618 return (-1);
09585a65 619
410c8acf 620 for (ks = *ksroot; ks; ks = ks->next) {
410c8acf 621 if (!KEYOK(ks, now))
622 continue;
7ed14135 623 if (!dodecrypt(ks, ty, b, bb, &seq)) {
426c0bc6 624 if (ks->f & KSF_LISTEN) {
625 T( trace(T_KEYSET, "keyset: implicitly activating keyset %u",
626 ks->seq); )
627 ks->f &= ~KSF_LISTEN;
628 }
629 return (dosequence(ks, seq));
410c8acf 630 }
410c8acf 631 }
e945d6e4 632 T( trace(T_KEYSET, "keyset: no matching keys, or incorrect MAC"); )
410c8acf 633 return (-1);
634}
635
636/*----- That's all, folks -------------------------------------------------*/