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