410c8acf |
1 | /* -*-c-*- |
2 | * |
737cc271 |
3 | * $Id: keyexch.c,v 1.9 2003/07/13 11:53:14 mdw Exp $ |
410c8acf |
4 | * |
5 | * Key exchange protocol |
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: keyexch.c,v $ |
737cc271 |
32 | * Revision 1.9 2003/07/13 11:53:14 mdw |
33 | * Add protocol commentary. |
34 | * |
7ed14135 |
35 | * Revision 1.8 2003/07/13 11:19:49 mdw |
36 | * Incopatible protocol fix! Include message type code under MAC tag to prevent |
37 | * cut-and-paste from key-exchange messages to general packet transport. |
38 | * |
2de0ad0f |
39 | * Revision 1.7 2003/05/17 11:01:28 mdw |
40 | * Handle flags on challenge timers correctly to prevent confusing the event |
41 | * list. |
42 | * |
9466fafa |
43 | * Revision 1.6 2003/04/06 10:26:35 mdw |
44 | * Report peer name on decrypt errors. |
45 | * |
5d418e24 |
46 | * Revision 1.5 2002/01/13 14:54:40 mdw |
47 | * Patch up zero-knowledge property by passing an encrypted log with a |
48 | * challenge, so that the prover can verify that the challenge is good. |
49 | * |
00e64b67 |
50 | * Revision 1.4 2001/06/22 19:40:36 mdw |
51 | * Support expiry of other peers' public keys. |
52 | * |
56814747 |
53 | * Revision 1.3 2001/06/19 22:07:09 mdw |
54 | * Cosmetic fixes. |
55 | * |
0617b6e7 |
56 | * Revision 1.2 2001/02/16 21:24:27 mdw |
57 | * Rewrite for new key exchange protocol. |
58 | * |
410c8acf |
59 | * Revision 1.1 2001/02/03 20:26:37 mdw |
60 | * Initial checkin. |
61 | * |
62 | */ |
63 | |
64 | /*----- Header files ------------------------------------------------------*/ |
65 | |
66 | #include "tripe.h" |
67 | |
737cc271 |
68 | /*----- Brief protocol overview -------------------------------------------* |
69 | * |
70 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let |
71 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote |
72 | * application of the symmetric packet protocol to a message; let |
73 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% |
74 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% |
75 | * be Bob's public key. |
76 | * |
77 | * At the beginning of the session, Alice chooses |
78 | * |
79 | * %$\rho_A \inr \{0, \ldots q - 1\}$% |
80 | * |
81 | * We also have: |
82 | * |
83 | * %$r_A = g^{\rho_A}$% Alice's challenge |
84 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie |
85 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, r_A, r_B, b^{\rho_A})$% |
86 | * Alice's challenge check value |
87 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply |
88 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% |
89 | * Alice and Bob's shared secret key |
90 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% |
91 | * Alice's switch request value |
92 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% |
93 | * Alice's switch confirm value |
94 | * |
95 | * The messages are then: |
96 | * |
97 | * %$\cookie{kx-pre-challenge}, r_A$% |
98 | * Initial greeting. In state @KXS_CHAL@. |
99 | * |
100 | * %$\cookie{kx-cookie}, r_A, c_B$% |
101 | * My table is full but I got your message. |
102 | * |
103 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
104 | * Here's a full challenge for you to answer. |
105 | * |
106 | * %$\cookie{kx-reply}, c_A, c_B, v_A, E_K(r_B^\alpha))$% |
107 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
108 | * to @KXS_COMMIT@. |
109 | * |
110 | * %$\cookie{kx-switch}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
111 | * Reply received: here's my reply. Committed; send data; move to |
112 | * @KXS_SWITCH@. |
113 | * |
114 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% |
115 | * Switch received. Committed; send data; move to @KXS_SWITCH@. |
116 | */ |
117 | |
410c8acf |
118 | /*----- Tunable parameters ------------------------------------------------*/ |
119 | |
2de0ad0f |
120 | #define T_VALID MIN(2) /* Challenge validity period */ |
121 | #define T_RETRY SEC(10) /* Challenge retransmit interval */ |
410c8acf |
122 | |
0617b6e7 |
123 | #define ISVALID(kx, now) ((now) < (kx)->t_valid) |
124 | |
125 | /*----- Various utilities -------------------------------------------------*/ |
410c8acf |
126 | |
127 | /* --- @hashmp@ --- * |
128 | * |
0617b6e7 |
129 | * Arguments: @HASH_CTX *r@ = pointer to hash context |
410c8acf |
130 | * @mp *m@ = pointer to multiprecision integer |
131 | * |
132 | * Returns: --- |
133 | * |
134 | * Use: Adds the hash of a multiprecision integer to the context. |
0617b6e7 |
135 | * Corrupts @buf_t@. |
410c8acf |
136 | */ |
137 | |
0617b6e7 |
138 | static void hashmp(HASH_CTX *r, mp *m) |
410c8acf |
139 | { |
140 | buf b; |
0617b6e7 |
141 | buf_init(&b, buf_t, sizeof(buf_t)); |
410c8acf |
142 | buf_putmp(&b, m); |
143 | assert(BOK(&b)); |
0617b6e7 |
144 | HASH(r, BBASE(&b), BLEN(&b)); |
410c8acf |
145 | } |
146 | |
5d418e24 |
147 | /* --- @mpcrypt@ --- * |
148 | * |
149 | * Arguments: @mp *d@ = the destination integer |
150 | * @mp *x@ = the plaintext/ciphertext integer |
151 | * @size_t sz@ = the expected size of the plaintext |
152 | * @const octet *k@ = pointer to key material |
153 | * @size_t ksz@ = size of the key |
154 | * |
155 | * Returns: The encrypted/decrypted integer. |
156 | * |
157 | * Use: Encrypts (or decrypts) a multiprecision integer using another |
158 | * multiprecision integer as the key. This is a slightly grotty |
159 | * way to do this, but it's easier than the alternatives. |
160 | */ |
161 | |
162 | static mp *mpcrypt(mp *d, mp *x, size_t sz, const octet *k, size_t ksz) |
163 | { |
164 | MGF_CTX m; |
165 | |
166 | MGF_INIT(&m, k, ksz, 0); |
167 | mp_storeb(x, buf_t, sz); |
168 | MGF_CRYPT(&m, buf_t, buf_t, sz); |
169 | return (mp_loadb(d, buf_t, sz)); |
170 | } |
171 | |
410c8acf |
172 | /* --- @timer@ --- * |
173 | * |
174 | * Arguments: @struct timeval *tv@ = the current time |
175 | * @void *v@ = pointer to key exchange context |
176 | * |
177 | * Returns: --- |
178 | * |
179 | * Use: Acts when the key exchange timer goes off. |
180 | */ |
181 | |
182 | static void timer(struct timeval *tv, void *v) |
183 | { |
184 | keyexch *kx = v; |
185 | kx->f &= ~KXF_TIMER; |
186 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) |
187 | kx_start(kx); |
188 | } |
189 | |
190 | /* --- @settimer@ --- * |
191 | * |
192 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
193 | * @time_t t@ = when to set the timer for |
194 | * |
195 | * Returns: --- |
196 | * |
197 | * Use: Sets the timer for the next key exchange attempt. |
198 | */ |
199 | |
200 | static void settimer(keyexch *kx, time_t t) |
201 | { |
202 | struct timeval tv; |
203 | if (kx->f & KXF_TIMER) |
204 | sel_rmtimer(&kx->t); |
205 | tv.tv_sec = t; |
206 | tv.tv_usec = 0; |
207 | sel_addtimer(&sel, &kx->t, &tv, timer, kx); |
208 | kx->f |= KXF_TIMER; |
209 | } |
210 | |
0617b6e7 |
211 | /*----- Challenge management ----------------------------------------------*/ |
212 | |
213 | /* --- Notes on challenge management --- * |
410c8acf |
214 | * |
0617b6e7 |
215 | * We may get multiple different replies to our key exchange; some will be |
216 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges |
217 | * received will be added to the table and given a full response. After |
218 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': |
219 | * our existing challenge, followed by a hash of the sender's challenge. We |
220 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All |
221 | * properly-formed cookies are assigned a table slot: if none is spare, a |
222 | * used slot is randomly selected and destroyed. A cookie always receives a |
223 | * full reply. |
224 | */ |
225 | |
226 | /* --- @kxc_destroy@ --- * |
227 | * |
228 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
410c8acf |
229 | * |
230 | * Returns: --- |
231 | * |
0617b6e7 |
232 | * Use: Disposes of a challenge block. |
410c8acf |
233 | */ |
234 | |
0617b6e7 |
235 | static void kxc_destroy(kxchal *kxc) |
410c8acf |
236 | { |
0617b6e7 |
237 | if (kxc->f & KXF_TIMER) |
238 | sel_rmtimer(&kxc->t); |
239 | mp_drop(kxc->c); |
240 | mp_drop(kxc->r); |
5d418e24 |
241 | mp_drop(kxc->ck); |
0617b6e7 |
242 | ks_drop(kxc->ks); |
243 | DESTROY(kxc); |
244 | } |
410c8acf |
245 | |
0617b6e7 |
246 | /* --- @kxc_stoptimer@ --- * |
247 | * |
248 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
249 | * |
250 | * Returns: --- |
251 | * |
252 | * Use: Stops the challenge's retry timer from sending messages. |
253 | * Useful when the state machine is in the endgame of the |
254 | * exchange. |
255 | */ |
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256 | |
0617b6e7 |
257 | static void kxc_stoptimer(kxchal *kxc) |
258 | { |
259 | if (kxc->f & KXF_TIMER) |
260 | sel_rmtimer(&kxc->t); |
2de0ad0f |
261 | kxc->f &= ~KXF_TIMER; |
0617b6e7 |
262 | } |
410c8acf |
263 | |
0617b6e7 |
264 | /* --- @kxc_new@ --- * |
265 | * |
266 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
0617b6e7 |
267 | * |
268 | * Returns: A pointer to the challenge block. |
269 | * |
270 | * Use: Returns a pointer to a new challenge block to fill in. |
271 | */ |
410c8acf |
272 | |
0617b6e7 |
273 | static kxchal *kxc_new(keyexch *kx) |
274 | { |
275 | kxchal *kxc; |
276 | unsigned i; |
277 | |
278 | /* --- If we're over reply threshold, discard one at random --- */ |
279 | |
280 | if (kx->nr < KX_NCHAL) |
281 | i = kx->nr++; |
282 | else { |
283 | i = rand_global.ops->range(&rand_global, KX_NCHAL); |
284 | kxc_destroy(kx->r[i]); |
410c8acf |
285 | } |
286 | |
0617b6e7 |
287 | /* --- Fill in the new structure --- */ |
410c8acf |
288 | |
0617b6e7 |
289 | kxc = CREATE(kxchal); |
290 | kxc->c = 0; |
291 | kxc->r = 0; |
5d418e24 |
292 | kxc->ck = 0; |
0617b6e7 |
293 | kxc->ks = 0; |
294 | kxc->kx = kx; |
295 | kxc->f = 0; |
296 | kx->r[i] = kxc; |
297 | return (kxc); |
298 | } |
410c8acf |
299 | |
0617b6e7 |
300 | /* --- @kxc_bychal@ --- * |
301 | * |
302 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
303 | * @mp *c@ = challenge from remote host |
304 | * |
305 | * Returns: Pointer to the challenge block, or null. |
306 | * |
307 | * Use: Finds a challenge block, given its challenge. |
308 | */ |
309 | |
310 | static kxchal *kxc_bychal(keyexch *kx, mp *c) |
311 | { |
312 | unsigned i; |
313 | |
314 | for (i = 0; i < kx->nr; i++) { |
315 | if (MP_EQ(c, kx->r[i]->c)) |
316 | return (kx->r[i]); |
317 | } |
318 | return (0); |
319 | } |
320 | |
321 | /* --- @kxc_byhc@ --- * |
322 | * |
323 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
324 | * @const octet *hc@ = challenge hash from remote host |
325 | * |
326 | * Returns: Pointer to the challenge block, or null. |
327 | * |
328 | * Use: Finds a challenge block, given a hash of its challenge. |
329 | */ |
410c8acf |
330 | |
0617b6e7 |
331 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
332 | { |
333 | unsigned i; |
334 | |
335 | for (i = 0; i < kx->nr; i++) { |
336 | if (memcmp(hc, kx->r[i]->hc, HASHSZ) == 0) |
337 | return (kx->r[i]); |
410c8acf |
338 | } |
0617b6e7 |
339 | return (0); |
340 | } |
341 | |
342 | /* --- @kxc_answer@ --- * |
343 | * |
344 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
345 | * @kxchal *kxc@ = pointer to challenge block |
346 | * |
347 | * Returns: --- |
348 | * |
349 | * Use: Sends a reply to the remote host, according to the data in |
350 | * this challenge block. |
351 | */ |
352 | |
353 | static void kxc_answer(keyexch *kx, kxchal *kxc); |
354 | |
355 | static void kxc_timer(struct timeval *tv, void *v) |
356 | { |
357 | kxchal *kxc = v; |
358 | kxc->f &= ~KXF_TIMER; |
359 | kxc_answer(kxc->kx, kxc); |
360 | } |
361 | |
362 | static void kxc_answer(keyexch *kx, kxchal *kxc) |
363 | { |
364 | stats *st = p_stats(kx->p); |
365 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | (kxc->r ? KX_REPLY : KX_CHAL)); |
366 | struct timeval tv; |
367 | buf bb; |
368 | |
369 | /* --- Build the reply packet --- */ |
370 | |
371 | if (!kxc->r) |
372 | buf_putmp(b, kx->c); |
373 | else |
374 | buf_put(b, kx->hc, HASHSZ); |
375 | buf_put(b, kxc->hc, HASHSZ); |
5d418e24 |
376 | buf_putmp(b, kxc->ck); |
0617b6e7 |
377 | |
378 | /* --- Maybe send an actual reply, if we have one --- */ |
410c8acf |
379 | |
0617b6e7 |
380 | if (!kxc->r) { |
381 | T( trace(T_KEYEXCH, "keyexch: resending challenge to `%s'", |
382 | p_name(kx->p)); ) |
383 | } else { |
384 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
385 | buf_init(&bb, buf_i, sizeof(buf_i)); |
386 | buf_putmp(&bb, kxc->r); |
387 | buf_flip(&bb); |
7ed14135 |
388 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); |
0617b6e7 |
389 | } |
390 | |
391 | /* --- Update the statistics --- */ |
392 | |
393 | if (BOK(b)) { |
394 | st->n_kxout++; |
395 | st->sz_kxout += BLEN(b); |
396 | p_txend(kx->p); |
397 | } |
398 | |
399 | /* --- Schedule another resend --- */ |
400 | |
401 | if (kxc->f & KXF_TIMER) |
402 | sel_rmtimer(&kxc->t); |
403 | gettimeofday(&tv, 0); |
404 | tv.tv_sec += T_RETRY; |
405 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); |
406 | kxc->f |= KXF_TIMER; |
407 | } |
408 | |
409 | /*----- Individual message handlers ---------------------------------------*/ |
410 | |
411 | /* --- @getreply@ --- * |
412 | * |
413 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
414 | * @mp *c@ = a challenge |
5d418e24 |
415 | * @mp *ck@ = the supplied expected-reply check value |
0617b6e7 |
416 | * |
417 | * Returns: A pointer to the reply, or null if the reply-hash was wrong. |
418 | * |
419 | * Use: Computes replies to challenges. |
420 | */ |
421 | |
5d418e24 |
422 | static mp *getreply(keyexch *kx, mp *c, mp *ck) |
0617b6e7 |
423 | { |
424 | mp *r = mpmont_exp(&mg, MP_NEW, c, kpriv.x); |
5d418e24 |
425 | mp *a; |
0617b6e7 |
426 | HASH_CTX h; |
5d418e24 |
427 | octet buf[HASHSZ]; |
428 | int ok; |
0617b6e7 |
429 | |
430 | HASH_INIT(&h); |
431 | HASH_STRING(&h, "tripe-expected-reply"); |
432 | hashmp(&h, c); |
433 | hashmp(&h, kx->c); |
434 | hashmp(&h, r); |
435 | HASH_DONE(&h, buf); |
5d418e24 |
436 | |
437 | a = mpcrypt(MP_NEW, ck, mp_octets(kpriv.dp.q), buf, sizeof(buf)); |
0617b6e7 |
438 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
439 | trace(T_CRYPTO, "crypto: computed reply = %s", mpstr(r)); |
440 | trace_block(T_CRYPTO, "crypto: computed reply hash", buf, HASHSZ); |
5d418e24 |
441 | trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(a)); |
0617b6e7 |
442 | })) |
5d418e24 |
443 | a = mpmont_exp(&mg, a, kpriv.dp.g, a); |
444 | ok = mp_eq(a, c); |
445 | if (!ok) { |
446 | a_warn("invalid expected-reply check from `%s'", p_name(kx->p)); |
447 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
448 | trace(T_CRYPTO, "crypto: computed challenge = %s", mpstr(a)); |
449 | })) |
0617b6e7 |
450 | mp_drop(r); |
0617b6e7 |
451 | } |
5d418e24 |
452 | mp_drop(a); |
453 | return (ok ? r : 0); |
0617b6e7 |
454 | } |
455 | |
456 | /* --- @dochallenge@ --- * |
457 | * |
458 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
459 | * @unsigned msg@ = message code for the packet |
460 | * @buf *b@ = buffer containing the packet |
461 | * |
462 | * Returns: Zero if OK, nonzero if the packet was rejected. |
463 | * |
464 | * Use: Processes a packet containing a challenge. |
465 | */ |
466 | |
467 | static int dochallenge(keyexch *kx, unsigned msg, buf *b) |
468 | { |
5d418e24 |
469 | mp *c = 0, *ck = 0; |
470 | const octet *hc = 0; |
0617b6e7 |
471 | kxchal *kxc; |
472 | HASH_CTX h; |
5d418e24 |
473 | octet buf[HASHSZ]; |
0617b6e7 |
474 | |
475 | /* --- Ensure that we're in a sensible state --- */ |
476 | |
477 | if (kx->s != KXS_CHAL) { |
478 | a_warn("unexpected challenge from `%s'", p_name(kx->p)); |
479 | goto bad; |
480 | } |
481 | |
482 | /* --- Unpack the packet --- */ |
483 | |
484 | if ((c = buf_getmp(b)) == 0 || |
485 | (msg >= KX_COOKIE && (hc = buf_get(b, HASHSZ)) == 0) || |
5d418e24 |
486 | (msg >= KX_CHAL && (ck = buf_getmp(b)) == 0) || |
0617b6e7 |
487 | BLEFT(b)) { |
488 | a_warn("malformed packet from `%s'", p_name(kx->p)); |
489 | goto bad; |
490 | } |
491 | |
492 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
493 | trace(T_CRYPTO, "crypto: challenge = %s", mpstr(c)); |
494 | if (hc) trace_block(T_CRYPTO, "crypto: cookie", hc, HASHSZ); |
5d418e24 |
495 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
496 | })) |
497 | |
498 | /* --- First, handle a bare challenge --- * |
499 | * |
500 | * If the table is heavily loaded, just emit a cookie and return. |
501 | */ |
502 | |
503 | if (!hc && kx->nr >= KX_THRESH) { |
504 | T( trace(T_KEYEXCH, "keyexch: too many challenges -- sending cookie"); ) |
505 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_COOKIE); |
506 | buf_putmp(b, kx->c); |
507 | HASH_INIT(&h); |
508 | HASH_STRING(&h, "tripe-cookie"); |
509 | hashmp(&h, c); |
510 | HASH_DONE(&h, buf_get(b, HASHSZ)); |
511 | p_txend(kx->p); |
512 | goto tidy; |
513 | } |
514 | |
515 | /* --- Discard a packet with an invalid cookie --- */ |
516 | |
517 | if (hc && memcmp(hc, kx->hc, HASHSZ) != 0) { |
518 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
519 | goto bad; |
520 | } |
521 | |
522 | /* --- Find a challenge block for this packet --- * |
410c8acf |
523 | * |
0617b6e7 |
524 | * If there isn't one already, create a new one. |
410c8acf |
525 | */ |
526 | |
0617b6e7 |
527 | if ((kxc = kxc_bychal(kx, c)) == 0) { |
528 | size_t x, y, z; |
529 | mp *r; |
530 | |
531 | /* --- Be careful here --- * |
532 | * |
533 | * If this is a full challenge, and it's the first time I've seen it, I |
534 | * want to be able to throw it away before committing a table entry to |
535 | * it. |
536 | */ |
537 | |
5d418e24 |
538 | if (!ck) |
0617b6e7 |
539 | kxc = kxc_new(kx); |
540 | else { |
5d418e24 |
541 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
542 | goto bad; |
543 | kxc = kxc_new(kx); |
544 | kxc->r = r; |
410c8acf |
545 | } |
0617b6e7 |
546 | kxc->c = mp_copy(c); |
547 | |
548 | /* --- Work out the cookie for this challenge --- */ |
549 | |
550 | HASH_INIT(&h); |
551 | HASH_STRING(&h, "tripe-cookie"); |
552 | hashmp(&h, kxc->c); |
553 | HASH_DONE(&h, kxc->hc); |
554 | |
555 | /* --- Compute the expected-reply hash --- */ |
556 | |
557 | HASH_INIT(&h); |
558 | HASH_STRING(&h, "tripe-expected-reply"); |
559 | hashmp(&h, kx->c); |
560 | hashmp(&h, kxc->c); |
561 | hashmp(&h, kx->rx); |
5d418e24 |
562 | HASH_DONE(&h, buf); |
563 | kxc->ck = mpcrypt(MP_NEW, kx->alpha, mp_octets(kpriv.dp.q), |
564 | buf, sizeof(buf)); |
0617b6e7 |
565 | |
566 | /* --- Work out the shared key --- */ |
567 | |
5d418e24 |
568 | trace(T_CRYPTO, "debug: c = %s", mpstr(c)); |
569 | trace(T_CRYPTO, "debug: alpha = %s", mpstr(kx->alpha)); |
0617b6e7 |
570 | r = mpmont_exp(&mg, MP_NEW, c, kx->alpha); |
5d418e24 |
571 | trace(T_CRYPTO, "debug: r = %s", mpstr(r)); |
0617b6e7 |
572 | |
573 | /* --- Compute the switch messages --- */ |
574 | |
575 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
576 | hashmp(&h, kx->c); hashmp(&h, kxc->c); |
577 | HASH_DONE(&h, kxc->hswrq_out); |
578 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
579 | hashmp(&h, kx->c); hashmp(&h, kxc->c); |
580 | HASH_DONE(&h, kxc->hswok_out); |
581 | |
582 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
583 | hashmp(&h, kxc->c); hashmp(&h, kx->c); |
584 | HASH_DONE(&h, kxc->hswrq_in); |
585 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
586 | hashmp(&h, kxc->c); hashmp(&h, kx->c); |
587 | HASH_DONE(&h, kxc->hswok_in); |
588 | |
589 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
590 | trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, HASHSZ); |
5d418e24 |
591 | trace_block(T_CRYPTO, "crypto: expected-reply hash", |
592 | buf, HASHSZ); |
593 | trace(T_CRYPTO, "crypto: my reply check = %s", mpstr(kxc->ck)); |
0617b6e7 |
594 | trace(T_CRYPTO, "crypto: shared secret = %s", mpstr(r)); |
595 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
596 | kxc->hswrq_out, HASHSZ); |
597 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
598 | kxc->hswok_out, HASHSZ); |
599 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
600 | kxc->hswrq_in, HASHSZ); |
601 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
602 | kxc->hswok_in, HASHSZ); |
603 | })) |
604 | |
605 | /* --- Create a new symmetric keyset --- */ |
606 | |
607 | buf_init(b, buf_o, sizeof(buf_o)); |
608 | buf_putmp(b, kx->c); x = BLEN(b); |
609 | buf_putmp(b, kxc->c); y = BLEN(b); |
610 | buf_putmp(b, r); z = BLEN(b); |
611 | assert(BOK(b)); |
612 | |
9466fafa |
613 | kxc->ks = ks_gen(BBASE(b), x, y, z, kx->p); |
0617b6e7 |
614 | mp_drop(r); |
410c8acf |
615 | } |
616 | |
0617b6e7 |
617 | /* --- Answer the challenge if we need to --- */ |
410c8acf |
618 | |
5d418e24 |
619 | if (ck && !kxc->r) { |
0617b6e7 |
620 | mp *r; |
5d418e24 |
621 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
622 | goto bad; |
623 | kxc->r = r; |
410c8acf |
624 | } |
0617b6e7 |
625 | |
626 | kxc_answer(kx, kxc); |
627 | |
628 | /* --- Tidy up and go home --- */ |
629 | |
630 | tidy: |
631 | mp_drop(c); |
5d418e24 |
632 | mp_drop(ck); |
0617b6e7 |
633 | return (0); |
634 | |
635 | bad: |
636 | mp_drop(c); |
5d418e24 |
637 | mp_drop(ck); |
0617b6e7 |
638 | return (-1); |
410c8acf |
639 | } |
640 | |
0617b6e7 |
641 | /* --- @resend@ --- * |
410c8acf |
642 | * |
643 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
644 | * |
645 | * Returns: --- |
646 | * |
0617b6e7 |
647 | * Use: Sends the next message for a key exchange. |
410c8acf |
648 | */ |
649 | |
0617b6e7 |
650 | static void resend(keyexch *kx) |
410c8acf |
651 | { |
0617b6e7 |
652 | kxchal *kxc; |
653 | buf bb; |
654 | stats *st = p_stats(kx->p); |
410c8acf |
655 | buf *b; |
656 | |
0617b6e7 |
657 | switch (kx->s) { |
658 | case KXS_CHAL: |
00e64b67 |
659 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
660 | p_name(kx->p)); ) |
0617b6e7 |
661 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
662 | buf_putmp(b, kx->c); |
663 | break; |
664 | case KXS_COMMIT: |
00e64b67 |
665 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
666 | p_name(kx->p)); ) |
0617b6e7 |
667 | kxc = kx->r[0]; |
668 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); |
669 | buf_put(b, kx->hc, HASHSZ); |
670 | buf_put(b, kxc->hc, HASHSZ); |
671 | buf_init(&bb, buf_i, sizeof(buf_i)); |
672 | buf_putmp(&bb, kxc->r); |
673 | buf_put(&bb, kxc->hswrq_out, HASHSZ); |
674 | buf_flip(&bb); |
7ed14135 |
675 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 |
676 | break; |
677 | case KXS_SWITCH: |
00e64b67 |
678 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 |
679 | p_name(kx->p)); ) |
680 | kxc = kx->r[0]; |
681 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); |
682 | buf_init(&bb, buf_i, sizeof(buf_i)); |
683 | buf_put(&bb, kxc->hswok_out, HASHSZ); |
684 | buf_flip(&bb); |
7ed14135 |
685 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 |
686 | break; |
687 | default: |
688 | abort(); |
410c8acf |
689 | } |
0617b6e7 |
690 | |
691 | if (BOK(b)) { |
692 | st->n_kxout++; |
693 | st->sz_kxout += BLEN(b); |
694 | p_txend(kx->p); |
695 | } |
696 | |
697 | if (kx->s < KXS_SWITCH) |
698 | settimer(kx, time(0) + T_RETRY); |
410c8acf |
699 | } |
700 | |
0617b6e7 |
701 | /* --- @matchreply@ --- * |
702 | * |
703 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
7ed14135 |
704 | * @unsigned ty@ = type of incoming message |
0617b6e7 |
705 | * @const octet *hc_in@ = a hash of his challenge |
706 | * @const octet *hc_out@ = a hash of my challenge (cookie) |
5d418e24 |
707 | * @mp *ck@ = his expected-reply hash (optional) |
0617b6e7 |
708 | * @buf *b@ = encrypted remainder of the packet |
709 | * |
710 | * Returns: A pointer to the challenge block if OK, or null on failure. |
711 | * |
712 | * Use: Checks a reply or switch packet, ensuring that its contents |
713 | * are sensible and correct. If they are, @*b@ is set to point |
714 | * to the remainder of the encrypted data, and the correct |
715 | * challenge is returned. |
716 | */ |
717 | |
7ed14135 |
718 | static kxchal *matchreply(keyexch *kx, unsigned ty, const octet *hc_in, |
5d418e24 |
719 | const octet *hc_out, mp *ck, buf *b) |
410c8acf |
720 | { |
0617b6e7 |
721 | kxchal *kxc; |
722 | buf bb; |
723 | mp *r = 0; |
724 | |
725 | /* --- Check the plaintext portions of the data --- */ |
726 | |
727 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
728 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, HASHSZ); |
729 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, HASHSZ); |
5d418e24 |
730 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
731 | })) |
732 | if (memcmp(hc_out, kx->hc, HASHSZ) != 0) { |
733 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
734 | goto bad; |
735 | } |
736 | if ((kxc = kxc_byhc(kx, hc_in)) == 0) { |
737 | a_warn("received reply for unknown challenge from `%s'", p_name(kx->p)); |
738 | goto bad; |
739 | } |
410c8acf |
740 | |
0617b6e7 |
741 | /* --- Maybe compute a reply for the challenge --- */ |
742 | |
743 | if (!kxc->r) { |
5d418e24 |
744 | if (!ck) { |
0617b6e7 |
745 | a_warn("unexpected switch request from `%s'", p_name(kx->p)); |
746 | goto bad; |
747 | } |
5d418e24 |
748 | if ((r = getreply(kx, kxc->c, ck)) == 0) |
0617b6e7 |
749 | goto bad; |
750 | kxc->r = r; |
751 | r = 0; |
752 | } |
753 | |
754 | /* --- Decrypt the rest of the packet --- */ |
755 | |
756 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
757 | if (ks_decrypt(kxc->ks, ty, b, &bb)) { |
0617b6e7 |
758 | a_warn("failed to decrypt reply from `%s'", p_name(kx->p)); |
759 | goto bad; |
410c8acf |
760 | } |
0617b6e7 |
761 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
762 | if ((r = buf_getmp(b)) == 0) { |
763 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
764 | goto bad; |
765 | } |
766 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
767 | trace(T_CRYPTO, "crypto: reply = %s", mpstr(r)); |
768 | })) |
769 | if (!mp_eq(r, kx->rx)) { |
770 | a_warn("incorrect reply from `%s'", p_name(kx->p)); |
771 | goto bad; |
772 | } |
773 | |
774 | /* --- Done --- */ |
775 | |
776 | mp_drop(r); |
777 | return (kxc); |
778 | |
779 | bad: |
780 | mp_drop(r); |
781 | return (0); |
410c8acf |
782 | } |
783 | |
0617b6e7 |
784 | /* --- @commit@ --- * |
410c8acf |
785 | * |
786 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
787 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf |
788 | * |
789 | * Returns: --- |
790 | * |
0617b6e7 |
791 | * Use: Commits to a particular challenge as being the `right' one, |
792 | * since a reply has arrived for it. |
410c8acf |
793 | */ |
794 | |
0617b6e7 |
795 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf |
796 | { |
0617b6e7 |
797 | unsigned i; |
410c8acf |
798 | |
0617b6e7 |
799 | for (i = 0; i < kx->nr; i++) { |
800 | if (kx->r[i] != kxc) |
801 | kxc_destroy(kx->r[i]); |
802 | } |
803 | kx->r[0] = kxc; |
804 | kx->nr = 1; |
805 | kxc_stoptimer(kxc); |
806 | ksl_link(kx->ks, kxc->ks); |
410c8acf |
807 | } |
808 | |
0617b6e7 |
809 | /* --- @doreply@ --- * |
410c8acf |
810 | * |
811 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
812 | * @buf *b@ = buffer containing packet |
410c8acf |
813 | * |
0617b6e7 |
814 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
815 | * |
0617b6e7 |
816 | * Use: Handles a reply packet. This doesn't handle the various |
817 | * switch packets: they're rather too different. |
410c8acf |
818 | */ |
819 | |
0617b6e7 |
820 | static int doreply(keyexch *kx, buf *b) |
410c8acf |
821 | { |
5d418e24 |
822 | const octet *hc_in, *hc_out; |
823 | mp *ck = 0; |
0617b6e7 |
824 | kxchal *kxc; |
825 | |
826 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { |
827 | a_warn("unexpected reply from `%s'", p_name(kx->p)); |
828 | goto bad; |
829 | } |
830 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
831 | (hc_out = buf_get(b, HASHSZ)) == 0 || |
5d418e24 |
832 | (ck = buf_getmp(b)) == 0) { |
0617b6e7 |
833 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
834 | goto bad; |
835 | } |
7ed14135 |
836 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_REPLY, |
837 | hc_in, hc_out, ck, b)) == 0) |
0617b6e7 |
838 | goto bad; |
839 | if (BLEFT(b)) { |
840 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
841 | goto bad; |
842 | } |
843 | if (kx->s == KXS_CHAL) { |
844 | commit(kx, kxc); |
845 | kx->s = KXS_COMMIT; |
846 | } |
847 | resend(kx); |
848 | return (0); |
849 | |
850 | bad: |
5d418e24 |
851 | mp_drop(ck); |
0617b6e7 |
852 | return (-1); |
410c8acf |
853 | } |
854 | |
0617b6e7 |
855 | /* --- @doswitch@ --- * |
410c8acf |
856 | * |
0617b6e7 |
857 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
858 | * @buf *b@ = pointer to buffer containing packet |
410c8acf |
859 | * |
0617b6e7 |
860 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
861 | * |
0617b6e7 |
862 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf |
863 | */ |
864 | |
0617b6e7 |
865 | static int doswitch(keyexch *kx, buf *b) |
410c8acf |
866 | { |
0617b6e7 |
867 | const octet *hc_in, *hc_out, *hswrq; |
868 | kxchal *kxc; |
410c8acf |
869 | |
0617b6e7 |
870 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
871 | (hc_out = buf_get(b, HASHSZ)) == 0) { |
872 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
873 | goto bad; |
410c8acf |
874 | } |
7ed14135 |
875 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_SWITCH, |
876 | hc_in, hc_out, 0, b)) == 0) |
0617b6e7 |
877 | goto bad; |
878 | if ((hswrq = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
879 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
880 | goto bad; |
881 | } |
882 | IF_TRACING(T_KEYEXCH, { |
883 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, HASHSZ); |
884 | }) |
885 | if (memcmp(hswrq, kxc->hswrq_in, HASHSZ) != 0) { |
886 | a_warn("incorrect switch request hash from `%s'", p_name(kx->p)); |
887 | goto bad; |
888 | } |
889 | switch (kx->s) { |
890 | case KXS_CHAL: |
891 | commit(kx, kxc); |
892 | case KXS_COMMIT: |
893 | ks_activate(kxc->ks); |
894 | settimer(kx, ks_tregen(kxc->ks)); |
895 | kx->s = KXS_SWITCH; |
896 | break; |
897 | } |
898 | resend(kx); |
899 | return (0); |
900 | |
901 | bad: |
902 | return (-1); |
410c8acf |
903 | } |
904 | |
0617b6e7 |
905 | /* --- @doswitchok@ --- * |
906 | * |
907 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
908 | * @buf *b@ = pointer to buffer containing packet |
909 | * |
910 | * Returns: Zero if OK, nonzero if the packet was rejected. |
911 | * |
912 | * Use: Handles a reply with a switch request bolted onto it. |
913 | */ |
914 | |
915 | static int doswitchok(keyexch *kx, buf *b) |
410c8acf |
916 | { |
0617b6e7 |
917 | const octet *hswok; |
918 | kxchal *kxc; |
919 | buf bb; |
410c8acf |
920 | |
0617b6e7 |
921 | if (kx->s < KXS_COMMIT) { |
922 | a_warn("unexpected switch confirmation from `%s'", p_name(kx->p)); |
923 | goto bad; |
410c8acf |
924 | } |
0617b6e7 |
925 | kxc = kx->r[0]; |
926 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
927 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, b, &bb)) { |
0617b6e7 |
928 | a_warn("failed to decrypt switch confirmation from `%s'", p_name(kx->p)); |
929 | goto bad; |
930 | } |
931 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
932 | if ((hswok = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
933 | a_warn("invalid switch confirmation from `%s'", p_name(kx->p)); |
934 | goto bad; |
935 | } |
936 | IF_TRACING(T_KEYEXCH, { |
937 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", hswok, HASHSZ); |
938 | }) |
939 | if (memcmp(hswok, kxc->hswok_in, HASHSZ) != 0) { |
940 | a_warn("incorrect switch confirmation hash from `%s'", p_name(kx->p)); |
941 | goto bad; |
942 | } |
943 | if (kx->s < KXS_SWITCH) { |
944 | ks_activate(kxc->ks); |
945 | settimer(kx, ks_tregen(kxc->ks)); |
946 | kx->s = KXS_SWITCH; |
947 | } |
948 | return (0); |
949 | |
950 | bad: |
951 | return (-1); |
952 | } |
953 | |
954 | /*----- Main code ---------------------------------------------------------*/ |
955 | |
956 | /* --- @stop@ --- * |
957 | * |
958 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
959 | * |
960 | * Returns: --- |
961 | * |
962 | * Use: Stops a key exchange dead in its tracks. Throws away all of |
963 | * the context information. The context is left in an |
964 | * inconsistent state. The only functions which understand this |
965 | * state are @kx_free@ and @kx_init@ (which cause it internally |
966 | * it), and @start@ (which expects it to be the prevailing |
967 | * state). |
968 | */ |
969 | |
970 | static void stop(keyexch *kx) |
971 | { |
972 | unsigned i; |
973 | |
00e64b67 |
974 | if (kx->f & KXF_DEAD) |
975 | return; |
976 | |
0617b6e7 |
977 | if (kx->f & KXF_TIMER) |
978 | sel_rmtimer(&kx->t); |
979 | for (i = 0; i < kx->nr; i++) |
980 | kxc_destroy(kx->r[i]); |
981 | mp_drop(kx->alpha); |
982 | mp_drop(kx->c); |
983 | mp_drop(kx->rx); |
00e64b67 |
984 | kx->t_valid = 0; |
985 | kx->f |= KXF_DEAD; |
986 | kx->f &= ~KXF_TIMER; |
0617b6e7 |
987 | } |
988 | |
989 | /* --- @start@ --- * |
990 | * |
991 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
992 | * @time_t now@ = the current time |
993 | * |
994 | * Returns: --- |
995 | * |
996 | * Use: Starts a new key exchange with the peer. The context must be |
997 | * in the bizarre state left by @stop@ or @kx_init@. |
998 | */ |
999 | |
1000 | static void start(keyexch *kx, time_t now) |
1001 | { |
1002 | HASH_CTX h; |
1003 | |
00e64b67 |
1004 | assert(kx->f & KXF_DEAD); |
1005 | |
1006 | kx->f &= ~KXF_DEAD; |
0617b6e7 |
1007 | kx->nr = 0; |
0617b6e7 |
1008 | kx->alpha = mprand_range(MP_NEW, kpriv.dp.q, &rand_global, 0); |
1009 | kx->c = mpmont_exp(&mg, MP_NEW, kpriv.dp.g, kx->alpha); |
1010 | kx->rx = mpmont_exp(&mg, MP_NEW, kx->kpub.y, kx->alpha); |
1011 | kx->s = KXS_CHAL; |
1012 | kx->t_valid = now + T_VALID; |
1013 | |
1014 | HASH_INIT(&h); |
1015 | HASH_STRING(&h, "tripe-cookie"); |
1016 | hashmp(&h, kx->c); |
1017 | HASH_DONE(&h, kx->hc); |
1018 | |
1019 | IF_TRACING(T_KEYEXCH, { |
1020 | trace(T_KEYEXCH, "keyexch: creating new challenge"); |
1021 | IF_TRACING(T_CRYPTO, { |
1022 | trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); |
1023 | trace(T_CRYPTO, "crypto: challenge = %s", mpstr(kx->c)); |
1024 | trace(T_CRYPTO, "crypto: expected response = %s", mpstr(kx->rx)); |
1025 | trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, HASHSZ); |
1026 | }) |
1027 | }) |
410c8acf |
1028 | } |
1029 | |
00e64b67 |
1030 | /* --- @checkpub@ --- * |
1031 | * |
1032 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1033 | * |
1034 | * Returns: Zero if OK, nonzero if the peer's public key has expired. |
1035 | * |
1036 | * Use: Deactivates the key-exchange until the peer acquires a new |
1037 | * public key. |
1038 | */ |
1039 | |
1040 | static int checkpub(keyexch *kx) |
1041 | { |
1042 | time_t now; |
1043 | if (kx->f & KXF_DEAD) |
1044 | return (-1); |
1045 | now = time(0); |
1046 | if (KEY_EXPIRED(now, kx->texp_kpub)) { |
1047 | stop(kx); |
1048 | a_warn("public key for `%s' has expired", p_name(kx->p)); |
1049 | dh_pubfree(&kx->kpub); |
1050 | kx->f &= ~KXF_PUBKEY; |
1051 | return (-1); |
1052 | } |
1053 | return (0); |
1054 | } |
1055 | |
0617b6e7 |
1056 | /* --- @kx_start@ --- * |
410c8acf |
1057 | * |
1058 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
1059 | * |
1060 | * Returns: --- |
1061 | * |
0617b6e7 |
1062 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1063 | * a new challenge is sent (unless the quiet timer forbids |
1064 | * this); if no exchange is in progress, one is commenced. |
410c8acf |
1065 | */ |
1066 | |
0617b6e7 |
1067 | void kx_start(keyexch *kx) |
410c8acf |
1068 | { |
1069 | time_t now = time(0); |
410c8acf |
1070 | |
00e64b67 |
1071 | if (checkpub(kx)) |
1072 | return; |
0617b6e7 |
1073 | if (!ISVALID(kx, now)) { |
1074 | stop(kx); |
1075 | start(kx, now); |
410c8acf |
1076 | } |
0617b6e7 |
1077 | resend(kx); |
1078 | } |
1079 | |
1080 | /* --- @kx_message@ --- * |
1081 | * |
1082 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1083 | * @unsigned msg@ = the message code |
1084 | * @buf *b@ = pointer to buffer containing the packet |
1085 | * |
1086 | * Returns: --- |
1087 | * |
1088 | * Use: Reads a packet containing key exchange messages and handles |
1089 | * it. |
1090 | */ |
1091 | |
1092 | void kx_message(keyexch *kx, unsigned msg, buf *b) |
1093 | { |
1094 | time_t now = time(0); |
1095 | stats *st = p_stats(kx->p); |
1096 | size_t sz = BSZ(b); |
1097 | int rc; |
1098 | |
1099 | #ifndef NTRACE |
1100 | static const char *const pkname[] = { |
1101 | "prechallenge", "cookie", "challenge", |
1102 | "reply", "switch request", "switch confirmation" |
1103 | }; |
1104 | #endif |
1105 | |
00e64b67 |
1106 | if (checkpub(kx)) |
1107 | return; |
1108 | |
0617b6e7 |
1109 | if (!ISVALID(kx, now)) { |
1110 | stop(kx); |
1111 | start(kx, now); |
410c8acf |
1112 | } |
0617b6e7 |
1113 | |
1114 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", |
1115 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) |
1116 | |
1117 | switch (msg) { |
1118 | case KX_PRECHAL: |
1119 | case KX_COOKIE: |
1120 | case KX_CHAL: |
1121 | rc = dochallenge(kx, msg, b); |
1122 | break; |
1123 | case KX_REPLY: |
1124 | rc = doreply(kx, b); |
1125 | break; |
1126 | case KX_SWITCH: |
1127 | rc = doswitch(kx, b); |
1128 | break; |
1129 | case KX_SWITCHOK: |
1130 | rc = doswitchok(kx, b); |
1131 | break; |
1132 | default: |
1133 | a_warn("unexpected key exchange message type %u from `%p'", |
1134 | p_name(kx->p)); |
1135 | rc = -1; |
1136 | break; |
410c8acf |
1137 | } |
410c8acf |
1138 | |
0617b6e7 |
1139 | if (rc) |
1140 | st->n_reject++; |
1141 | else { |
1142 | st->n_kxin++; |
1143 | st->sz_kxin += sz; |
1144 | } |
410c8acf |
1145 | } |
1146 | |
1147 | /* --- @kx_free@ --- * |
1148 | * |
1149 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1150 | * |
1151 | * Returns: --- |
1152 | * |
1153 | * Use: Frees everything in a key exchange context. |
1154 | */ |
1155 | |
1156 | void kx_free(keyexch *kx) |
1157 | { |
0617b6e7 |
1158 | stop(kx); |
00e64b67 |
1159 | if (kx->f & KXF_PUBKEY) |
1160 | dh_pubfree(&kx->kpub); |
410c8acf |
1161 | } |
1162 | |
1163 | /* --- @kx_newkeys@ --- * |
1164 | * |
1165 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1166 | * |
1167 | * Returns: --- |
1168 | * |
1169 | * Use: Informs the key exchange module that its keys may have |
1170 | * changed. If fetching the new keys fails, the peer will be |
1171 | * destroyed, we log messages and struggle along with the old |
1172 | * keys. |
1173 | */ |
1174 | |
1175 | void kx_newkeys(keyexch *kx) |
1176 | { |
1177 | dh_pub dp; |
1178 | |
00e64b67 |
1179 | if (km_getpubkey(p_name(kx->p), &dp, &kx->texp_kpub)) |
410c8acf |
1180 | return; |
00e64b67 |
1181 | if (kx->f & KXF_PUBKEY) |
1182 | dh_pubfree(&kx->kpub); |
410c8acf |
1183 | kx->kpub = dp; |
00e64b67 |
1184 | kx->f |= KXF_PUBKEY; |
1185 | if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { |
410c8acf |
1186 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1187 | p_name(kx->p)); ) |
00e64b67 |
1188 | stop(kx); |
1189 | start(kx, time(0)); |
1190 | resend(kx); |
410c8acf |
1191 | } |
1192 | } |
1193 | |
1194 | /* --- @kx_init@ --- * |
1195 | * |
1196 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1197 | * @peer *p@ = pointer to peer context |
1198 | * @keyset **ks@ = pointer to keyset list |
1199 | * |
1200 | * Returns: Zero if OK, nonzero if it failed. |
1201 | * |
1202 | * Use: Initializes a key exchange module. The module currently |
1203 | * contains no keys, and will attempt to initiate a key |
1204 | * exchange. |
1205 | */ |
1206 | |
1207 | int kx_init(keyexch *kx, peer *p, keyset **ks) |
1208 | { |
1209 | kx->ks = ks; |
1210 | kx->p = p; |
00e64b67 |
1211 | if (km_getpubkey(p_name(p), &kx->kpub, &kx->texp_kpub)) |
410c8acf |
1212 | return (-1); |
00e64b67 |
1213 | kx->f = KXF_DEAD | KXF_PUBKEY; |
0617b6e7 |
1214 | start(kx, time(0)); |
1215 | resend(kx); |
410c8acf |
1216 | return (0); |
1217 | } |
1218 | |
1219 | /*----- That's all, folks -------------------------------------------------*/ |