410c8acf |
1 | /* -*-c-*- |
2 | * |
dd9647cc |
3 | * $Id: keyexch.c,v 1.10 2003/10/15 09:29:38 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 $ |
dd9647cc |
32 | * Revision 1.10 2003/10/15 09:29:38 mdw |
33 | * Cosmetic fix to changelog comment. |
34 | * |
737cc271 |
35 | * Revision 1.9 2003/07/13 11:53:14 mdw |
36 | * Add protocol commentary. |
37 | * |
7ed14135 |
38 | * Revision 1.8 2003/07/13 11:19:49 mdw |
dd9647cc |
39 | * Incompatible protocol fix! Include message type code under MAC tag to |
40 | * prevent cut-and-paste from key-exchange messages to general packet |
41 | * transport. |
7ed14135 |
42 | * |
2de0ad0f |
43 | * Revision 1.7 2003/05/17 11:01:28 mdw |
44 | * Handle flags on challenge timers correctly to prevent confusing the event |
45 | * list. |
46 | * |
9466fafa |
47 | * Revision 1.6 2003/04/06 10:26:35 mdw |
48 | * Report peer name on decrypt errors. |
49 | * |
5d418e24 |
50 | * Revision 1.5 2002/01/13 14:54:40 mdw |
51 | * Patch up zero-knowledge property by passing an encrypted log with a |
52 | * challenge, so that the prover can verify that the challenge is good. |
53 | * |
00e64b67 |
54 | * Revision 1.4 2001/06/22 19:40:36 mdw |
55 | * Support expiry of other peers' public keys. |
56 | * |
56814747 |
57 | * Revision 1.3 2001/06/19 22:07:09 mdw |
58 | * Cosmetic fixes. |
59 | * |
0617b6e7 |
60 | * Revision 1.2 2001/02/16 21:24:27 mdw |
61 | * Rewrite for new key exchange protocol. |
62 | * |
410c8acf |
63 | * Revision 1.1 2001/02/03 20:26:37 mdw |
64 | * Initial checkin. |
65 | * |
66 | */ |
67 | |
68 | /*----- Header files ------------------------------------------------------*/ |
69 | |
70 | #include "tripe.h" |
71 | |
737cc271 |
72 | /*----- Brief protocol overview -------------------------------------------* |
73 | * |
74 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let |
75 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote |
76 | * application of the symmetric packet protocol to a message; let |
77 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% |
78 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% |
79 | * be Bob's public key. |
80 | * |
81 | * At the beginning of the session, Alice chooses |
82 | * |
83 | * %$\rho_A \inr \{0, \ldots q - 1\}$% |
84 | * |
85 | * We also have: |
86 | * |
87 | * %$r_A = g^{\rho_A}$% Alice's challenge |
88 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie |
89 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, r_A, r_B, b^{\rho_A})$% |
90 | * Alice's challenge check value |
91 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply |
92 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% |
93 | * Alice and Bob's shared secret key |
94 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% |
95 | * Alice's switch request value |
96 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% |
97 | * Alice's switch confirm value |
98 | * |
99 | * The messages are then: |
100 | * |
101 | * %$\cookie{kx-pre-challenge}, r_A$% |
102 | * Initial greeting. In state @KXS_CHAL@. |
103 | * |
104 | * %$\cookie{kx-cookie}, r_A, c_B$% |
105 | * My table is full but I got your message. |
106 | * |
107 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
108 | * Here's a full challenge for you to answer. |
109 | * |
110 | * %$\cookie{kx-reply}, c_A, c_B, v_A, E_K(r_B^\alpha))$% |
111 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
112 | * to @KXS_COMMIT@. |
113 | * |
114 | * %$\cookie{kx-switch}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
115 | * Reply received: here's my reply. Committed; send data; move to |
116 | * @KXS_SWITCH@. |
117 | * |
118 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% |
119 | * Switch received. Committed; send data; move to @KXS_SWITCH@. |
120 | */ |
121 | |
410c8acf |
122 | /*----- Tunable parameters ------------------------------------------------*/ |
123 | |
2de0ad0f |
124 | #define T_VALID MIN(2) /* Challenge validity period */ |
125 | #define T_RETRY SEC(10) /* Challenge retransmit interval */ |
410c8acf |
126 | |
0617b6e7 |
127 | #define ISVALID(kx, now) ((now) < (kx)->t_valid) |
128 | |
129 | /*----- Various utilities -------------------------------------------------*/ |
410c8acf |
130 | |
131 | /* --- @hashmp@ --- * |
132 | * |
0617b6e7 |
133 | * Arguments: @HASH_CTX *r@ = pointer to hash context |
410c8acf |
134 | * @mp *m@ = pointer to multiprecision integer |
135 | * |
136 | * Returns: --- |
137 | * |
138 | * Use: Adds the hash of a multiprecision integer to the context. |
0617b6e7 |
139 | * Corrupts @buf_t@. |
410c8acf |
140 | */ |
141 | |
0617b6e7 |
142 | static void hashmp(HASH_CTX *r, mp *m) |
410c8acf |
143 | { |
144 | buf b; |
0617b6e7 |
145 | buf_init(&b, buf_t, sizeof(buf_t)); |
410c8acf |
146 | buf_putmp(&b, m); |
147 | assert(BOK(&b)); |
0617b6e7 |
148 | HASH(r, BBASE(&b), BLEN(&b)); |
410c8acf |
149 | } |
150 | |
5d418e24 |
151 | /* --- @mpcrypt@ --- * |
152 | * |
153 | * Arguments: @mp *d@ = the destination integer |
154 | * @mp *x@ = the plaintext/ciphertext integer |
155 | * @size_t sz@ = the expected size of the plaintext |
156 | * @const octet *k@ = pointer to key material |
157 | * @size_t ksz@ = size of the key |
158 | * |
159 | * Returns: The encrypted/decrypted integer. |
160 | * |
161 | * Use: Encrypts (or decrypts) a multiprecision integer using another |
162 | * multiprecision integer as the key. This is a slightly grotty |
163 | * way to do this, but it's easier than the alternatives. |
164 | */ |
165 | |
166 | static mp *mpcrypt(mp *d, mp *x, size_t sz, const octet *k, size_t ksz) |
167 | { |
168 | MGF_CTX m; |
169 | |
170 | MGF_INIT(&m, k, ksz, 0); |
171 | mp_storeb(x, buf_t, sz); |
172 | MGF_CRYPT(&m, buf_t, buf_t, sz); |
173 | return (mp_loadb(d, buf_t, sz)); |
174 | } |
175 | |
410c8acf |
176 | /* --- @timer@ --- * |
177 | * |
178 | * Arguments: @struct timeval *tv@ = the current time |
179 | * @void *v@ = pointer to key exchange context |
180 | * |
181 | * Returns: --- |
182 | * |
183 | * Use: Acts when the key exchange timer goes off. |
184 | */ |
185 | |
186 | static void timer(struct timeval *tv, void *v) |
187 | { |
188 | keyexch *kx = v; |
189 | kx->f &= ~KXF_TIMER; |
190 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) |
191 | kx_start(kx); |
192 | } |
193 | |
194 | /* --- @settimer@ --- * |
195 | * |
196 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
197 | * @time_t t@ = when to set the timer for |
198 | * |
199 | * Returns: --- |
200 | * |
201 | * Use: Sets the timer for the next key exchange attempt. |
202 | */ |
203 | |
204 | static void settimer(keyexch *kx, time_t t) |
205 | { |
206 | struct timeval tv; |
207 | if (kx->f & KXF_TIMER) |
208 | sel_rmtimer(&kx->t); |
209 | tv.tv_sec = t; |
210 | tv.tv_usec = 0; |
211 | sel_addtimer(&sel, &kx->t, &tv, timer, kx); |
212 | kx->f |= KXF_TIMER; |
213 | } |
214 | |
0617b6e7 |
215 | /*----- Challenge management ----------------------------------------------*/ |
216 | |
217 | /* --- Notes on challenge management --- * |
410c8acf |
218 | * |
0617b6e7 |
219 | * We may get multiple different replies to our key exchange; some will be |
220 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges |
221 | * received will be added to the table and given a full response. After |
222 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': |
223 | * our existing challenge, followed by a hash of the sender's challenge. We |
224 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All |
225 | * properly-formed cookies are assigned a table slot: if none is spare, a |
226 | * used slot is randomly selected and destroyed. A cookie always receives a |
227 | * full reply. |
228 | */ |
229 | |
230 | /* --- @kxc_destroy@ --- * |
231 | * |
232 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
410c8acf |
233 | * |
234 | * Returns: --- |
235 | * |
0617b6e7 |
236 | * Use: Disposes of a challenge block. |
410c8acf |
237 | */ |
238 | |
0617b6e7 |
239 | static void kxc_destroy(kxchal *kxc) |
410c8acf |
240 | { |
0617b6e7 |
241 | if (kxc->f & KXF_TIMER) |
242 | sel_rmtimer(&kxc->t); |
243 | mp_drop(kxc->c); |
244 | mp_drop(kxc->r); |
5d418e24 |
245 | mp_drop(kxc->ck); |
0617b6e7 |
246 | ks_drop(kxc->ks); |
247 | DESTROY(kxc); |
248 | } |
410c8acf |
249 | |
0617b6e7 |
250 | /* --- @kxc_stoptimer@ --- * |
251 | * |
252 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
253 | * |
254 | * Returns: --- |
255 | * |
256 | * Use: Stops the challenge's retry timer from sending messages. |
257 | * Useful when the state machine is in the endgame of the |
258 | * exchange. |
259 | */ |
410c8acf |
260 | |
0617b6e7 |
261 | static void kxc_stoptimer(kxchal *kxc) |
262 | { |
263 | if (kxc->f & KXF_TIMER) |
264 | sel_rmtimer(&kxc->t); |
2de0ad0f |
265 | kxc->f &= ~KXF_TIMER; |
0617b6e7 |
266 | } |
410c8acf |
267 | |
0617b6e7 |
268 | /* --- @kxc_new@ --- * |
269 | * |
270 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
0617b6e7 |
271 | * |
272 | * Returns: A pointer to the challenge block. |
273 | * |
274 | * Use: Returns a pointer to a new challenge block to fill in. |
275 | */ |
410c8acf |
276 | |
0617b6e7 |
277 | static kxchal *kxc_new(keyexch *kx) |
278 | { |
279 | kxchal *kxc; |
280 | unsigned i; |
281 | |
282 | /* --- If we're over reply threshold, discard one at random --- */ |
283 | |
284 | if (kx->nr < KX_NCHAL) |
285 | i = kx->nr++; |
286 | else { |
287 | i = rand_global.ops->range(&rand_global, KX_NCHAL); |
288 | kxc_destroy(kx->r[i]); |
410c8acf |
289 | } |
290 | |
0617b6e7 |
291 | /* --- Fill in the new structure --- */ |
410c8acf |
292 | |
0617b6e7 |
293 | kxc = CREATE(kxchal); |
294 | kxc->c = 0; |
295 | kxc->r = 0; |
5d418e24 |
296 | kxc->ck = 0; |
0617b6e7 |
297 | kxc->ks = 0; |
298 | kxc->kx = kx; |
299 | kxc->f = 0; |
300 | kx->r[i] = kxc; |
301 | return (kxc); |
302 | } |
410c8acf |
303 | |
0617b6e7 |
304 | /* --- @kxc_bychal@ --- * |
305 | * |
306 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
307 | * @mp *c@ = challenge from remote host |
308 | * |
309 | * Returns: Pointer to the challenge block, or null. |
310 | * |
311 | * Use: Finds a challenge block, given its challenge. |
312 | */ |
313 | |
314 | static kxchal *kxc_bychal(keyexch *kx, mp *c) |
315 | { |
316 | unsigned i; |
317 | |
318 | for (i = 0; i < kx->nr; i++) { |
319 | if (MP_EQ(c, kx->r[i]->c)) |
320 | return (kx->r[i]); |
321 | } |
322 | return (0); |
323 | } |
324 | |
325 | /* --- @kxc_byhc@ --- * |
326 | * |
327 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
328 | * @const octet *hc@ = challenge hash from remote host |
329 | * |
330 | * Returns: Pointer to the challenge block, or null. |
331 | * |
332 | * Use: Finds a challenge block, given a hash of its challenge. |
333 | */ |
410c8acf |
334 | |
0617b6e7 |
335 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
336 | { |
337 | unsigned i; |
338 | |
339 | for (i = 0; i < kx->nr; i++) { |
340 | if (memcmp(hc, kx->r[i]->hc, HASHSZ) == 0) |
341 | return (kx->r[i]); |
410c8acf |
342 | } |
0617b6e7 |
343 | return (0); |
344 | } |
345 | |
346 | /* --- @kxc_answer@ --- * |
347 | * |
348 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
349 | * @kxchal *kxc@ = pointer to challenge block |
350 | * |
351 | * Returns: --- |
352 | * |
353 | * Use: Sends a reply to the remote host, according to the data in |
354 | * this challenge block. |
355 | */ |
356 | |
357 | static void kxc_answer(keyexch *kx, kxchal *kxc); |
358 | |
359 | static void kxc_timer(struct timeval *tv, void *v) |
360 | { |
361 | kxchal *kxc = v; |
362 | kxc->f &= ~KXF_TIMER; |
363 | kxc_answer(kxc->kx, kxc); |
364 | } |
365 | |
366 | static void kxc_answer(keyexch *kx, kxchal *kxc) |
367 | { |
368 | stats *st = p_stats(kx->p); |
369 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | (kxc->r ? KX_REPLY : KX_CHAL)); |
370 | struct timeval tv; |
371 | buf bb; |
372 | |
373 | /* --- Build the reply packet --- */ |
374 | |
375 | if (!kxc->r) |
376 | buf_putmp(b, kx->c); |
377 | else |
378 | buf_put(b, kx->hc, HASHSZ); |
379 | buf_put(b, kxc->hc, HASHSZ); |
5d418e24 |
380 | buf_putmp(b, kxc->ck); |
0617b6e7 |
381 | |
382 | /* --- Maybe send an actual reply, if we have one --- */ |
410c8acf |
383 | |
0617b6e7 |
384 | if (!kxc->r) { |
385 | T( trace(T_KEYEXCH, "keyexch: resending challenge to `%s'", |
386 | p_name(kx->p)); ) |
387 | } else { |
388 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
389 | buf_init(&bb, buf_i, sizeof(buf_i)); |
390 | buf_putmp(&bb, kxc->r); |
391 | buf_flip(&bb); |
7ed14135 |
392 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); |
0617b6e7 |
393 | } |
394 | |
395 | /* --- Update the statistics --- */ |
396 | |
397 | if (BOK(b)) { |
398 | st->n_kxout++; |
399 | st->sz_kxout += BLEN(b); |
400 | p_txend(kx->p); |
401 | } |
402 | |
403 | /* --- Schedule another resend --- */ |
404 | |
405 | if (kxc->f & KXF_TIMER) |
406 | sel_rmtimer(&kxc->t); |
407 | gettimeofday(&tv, 0); |
408 | tv.tv_sec += T_RETRY; |
409 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); |
410 | kxc->f |= KXF_TIMER; |
411 | } |
412 | |
413 | /*----- Individual message handlers ---------------------------------------*/ |
414 | |
415 | /* --- @getreply@ --- * |
416 | * |
417 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
418 | * @mp *c@ = a challenge |
5d418e24 |
419 | * @mp *ck@ = the supplied expected-reply check value |
0617b6e7 |
420 | * |
421 | * Returns: A pointer to the reply, or null if the reply-hash was wrong. |
422 | * |
423 | * Use: Computes replies to challenges. |
424 | */ |
425 | |
5d418e24 |
426 | static mp *getreply(keyexch *kx, mp *c, mp *ck) |
0617b6e7 |
427 | { |
428 | mp *r = mpmont_exp(&mg, MP_NEW, c, kpriv.x); |
5d418e24 |
429 | mp *a; |
0617b6e7 |
430 | HASH_CTX h; |
5d418e24 |
431 | octet buf[HASHSZ]; |
432 | int ok; |
0617b6e7 |
433 | |
434 | HASH_INIT(&h); |
435 | HASH_STRING(&h, "tripe-expected-reply"); |
436 | hashmp(&h, c); |
437 | hashmp(&h, kx->c); |
438 | hashmp(&h, r); |
439 | HASH_DONE(&h, buf); |
5d418e24 |
440 | |
441 | a = mpcrypt(MP_NEW, ck, mp_octets(kpriv.dp.q), buf, sizeof(buf)); |
0617b6e7 |
442 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
443 | trace(T_CRYPTO, "crypto: computed reply = %s", mpstr(r)); |
444 | trace_block(T_CRYPTO, "crypto: computed reply hash", buf, HASHSZ); |
5d418e24 |
445 | trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(a)); |
0617b6e7 |
446 | })) |
5d418e24 |
447 | a = mpmont_exp(&mg, a, kpriv.dp.g, a); |
448 | ok = mp_eq(a, c); |
449 | if (!ok) { |
450 | a_warn("invalid expected-reply check from `%s'", p_name(kx->p)); |
451 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
452 | trace(T_CRYPTO, "crypto: computed challenge = %s", mpstr(a)); |
453 | })) |
0617b6e7 |
454 | mp_drop(r); |
0617b6e7 |
455 | } |
5d418e24 |
456 | mp_drop(a); |
457 | return (ok ? r : 0); |
0617b6e7 |
458 | } |
459 | |
460 | /* --- @dochallenge@ --- * |
461 | * |
462 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
463 | * @unsigned msg@ = message code for the packet |
464 | * @buf *b@ = buffer containing the packet |
465 | * |
466 | * Returns: Zero if OK, nonzero if the packet was rejected. |
467 | * |
468 | * Use: Processes a packet containing a challenge. |
469 | */ |
470 | |
471 | static int dochallenge(keyexch *kx, unsigned msg, buf *b) |
472 | { |
5d418e24 |
473 | mp *c = 0, *ck = 0; |
474 | const octet *hc = 0; |
0617b6e7 |
475 | kxchal *kxc; |
476 | HASH_CTX h; |
5d418e24 |
477 | octet buf[HASHSZ]; |
0617b6e7 |
478 | |
479 | /* --- Ensure that we're in a sensible state --- */ |
480 | |
481 | if (kx->s != KXS_CHAL) { |
482 | a_warn("unexpected challenge from `%s'", p_name(kx->p)); |
483 | goto bad; |
484 | } |
485 | |
486 | /* --- Unpack the packet --- */ |
487 | |
488 | if ((c = buf_getmp(b)) == 0 || |
489 | (msg >= KX_COOKIE && (hc = buf_get(b, HASHSZ)) == 0) || |
5d418e24 |
490 | (msg >= KX_CHAL && (ck = buf_getmp(b)) == 0) || |
0617b6e7 |
491 | BLEFT(b)) { |
492 | a_warn("malformed packet from `%s'", p_name(kx->p)); |
493 | goto bad; |
494 | } |
495 | |
496 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
497 | trace(T_CRYPTO, "crypto: challenge = %s", mpstr(c)); |
498 | if (hc) trace_block(T_CRYPTO, "crypto: cookie", hc, HASHSZ); |
5d418e24 |
499 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
500 | })) |
501 | |
502 | /* --- First, handle a bare challenge --- * |
503 | * |
504 | * If the table is heavily loaded, just emit a cookie and return. |
505 | */ |
506 | |
507 | if (!hc && kx->nr >= KX_THRESH) { |
508 | T( trace(T_KEYEXCH, "keyexch: too many challenges -- sending cookie"); ) |
509 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_COOKIE); |
510 | buf_putmp(b, kx->c); |
511 | HASH_INIT(&h); |
512 | HASH_STRING(&h, "tripe-cookie"); |
513 | hashmp(&h, c); |
514 | HASH_DONE(&h, buf_get(b, HASHSZ)); |
515 | p_txend(kx->p); |
516 | goto tidy; |
517 | } |
518 | |
519 | /* --- Discard a packet with an invalid cookie --- */ |
520 | |
521 | if (hc && memcmp(hc, kx->hc, HASHSZ) != 0) { |
522 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
523 | goto bad; |
524 | } |
525 | |
526 | /* --- Find a challenge block for this packet --- * |
410c8acf |
527 | * |
0617b6e7 |
528 | * If there isn't one already, create a new one. |
410c8acf |
529 | */ |
530 | |
0617b6e7 |
531 | if ((kxc = kxc_bychal(kx, c)) == 0) { |
532 | size_t x, y, z; |
533 | mp *r; |
534 | |
535 | /* --- Be careful here --- * |
536 | * |
537 | * If this is a full challenge, and it's the first time I've seen it, I |
538 | * want to be able to throw it away before committing a table entry to |
539 | * it. |
540 | */ |
541 | |
5d418e24 |
542 | if (!ck) |
0617b6e7 |
543 | kxc = kxc_new(kx); |
544 | else { |
5d418e24 |
545 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
546 | goto bad; |
547 | kxc = kxc_new(kx); |
548 | kxc->r = r; |
410c8acf |
549 | } |
0617b6e7 |
550 | kxc->c = mp_copy(c); |
551 | |
552 | /* --- Work out the cookie for this challenge --- */ |
553 | |
554 | HASH_INIT(&h); |
555 | HASH_STRING(&h, "tripe-cookie"); |
556 | hashmp(&h, kxc->c); |
557 | HASH_DONE(&h, kxc->hc); |
558 | |
559 | /* --- Compute the expected-reply hash --- */ |
560 | |
561 | HASH_INIT(&h); |
562 | HASH_STRING(&h, "tripe-expected-reply"); |
563 | hashmp(&h, kx->c); |
564 | hashmp(&h, kxc->c); |
565 | hashmp(&h, kx->rx); |
5d418e24 |
566 | HASH_DONE(&h, buf); |
567 | kxc->ck = mpcrypt(MP_NEW, kx->alpha, mp_octets(kpriv.dp.q), |
568 | buf, sizeof(buf)); |
0617b6e7 |
569 | |
570 | /* --- Work out the shared key --- */ |
571 | |
5d418e24 |
572 | trace(T_CRYPTO, "debug: c = %s", mpstr(c)); |
573 | trace(T_CRYPTO, "debug: alpha = %s", mpstr(kx->alpha)); |
0617b6e7 |
574 | r = mpmont_exp(&mg, MP_NEW, c, kx->alpha); |
5d418e24 |
575 | trace(T_CRYPTO, "debug: r = %s", mpstr(r)); |
0617b6e7 |
576 | |
577 | /* --- Compute the switch messages --- */ |
578 | |
579 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
580 | hashmp(&h, kx->c); hashmp(&h, kxc->c); |
581 | HASH_DONE(&h, kxc->hswrq_out); |
582 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
583 | hashmp(&h, kx->c); hashmp(&h, kxc->c); |
584 | HASH_DONE(&h, kxc->hswok_out); |
585 | |
586 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
587 | hashmp(&h, kxc->c); hashmp(&h, kx->c); |
588 | HASH_DONE(&h, kxc->hswrq_in); |
589 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
590 | hashmp(&h, kxc->c); hashmp(&h, kx->c); |
591 | HASH_DONE(&h, kxc->hswok_in); |
592 | |
593 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
594 | trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, HASHSZ); |
5d418e24 |
595 | trace_block(T_CRYPTO, "crypto: expected-reply hash", |
596 | buf, HASHSZ); |
597 | trace(T_CRYPTO, "crypto: my reply check = %s", mpstr(kxc->ck)); |
0617b6e7 |
598 | trace(T_CRYPTO, "crypto: shared secret = %s", mpstr(r)); |
599 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
600 | kxc->hswrq_out, HASHSZ); |
601 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
602 | kxc->hswok_out, HASHSZ); |
603 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
604 | kxc->hswrq_in, HASHSZ); |
605 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
606 | kxc->hswok_in, HASHSZ); |
607 | })) |
608 | |
609 | /* --- Create a new symmetric keyset --- */ |
610 | |
611 | buf_init(b, buf_o, sizeof(buf_o)); |
612 | buf_putmp(b, kx->c); x = BLEN(b); |
613 | buf_putmp(b, kxc->c); y = BLEN(b); |
614 | buf_putmp(b, r); z = BLEN(b); |
615 | assert(BOK(b)); |
616 | |
9466fafa |
617 | kxc->ks = ks_gen(BBASE(b), x, y, z, kx->p); |
0617b6e7 |
618 | mp_drop(r); |
410c8acf |
619 | } |
620 | |
0617b6e7 |
621 | /* --- Answer the challenge if we need to --- */ |
410c8acf |
622 | |
5d418e24 |
623 | if (ck && !kxc->r) { |
0617b6e7 |
624 | mp *r; |
5d418e24 |
625 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
626 | goto bad; |
627 | kxc->r = r; |
410c8acf |
628 | } |
0617b6e7 |
629 | |
630 | kxc_answer(kx, kxc); |
631 | |
632 | /* --- Tidy up and go home --- */ |
633 | |
634 | tidy: |
635 | mp_drop(c); |
5d418e24 |
636 | mp_drop(ck); |
0617b6e7 |
637 | return (0); |
638 | |
639 | bad: |
640 | mp_drop(c); |
5d418e24 |
641 | mp_drop(ck); |
0617b6e7 |
642 | return (-1); |
410c8acf |
643 | } |
644 | |
0617b6e7 |
645 | /* --- @resend@ --- * |
410c8acf |
646 | * |
647 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
648 | * |
649 | * Returns: --- |
650 | * |
0617b6e7 |
651 | * Use: Sends the next message for a key exchange. |
410c8acf |
652 | */ |
653 | |
0617b6e7 |
654 | static void resend(keyexch *kx) |
410c8acf |
655 | { |
0617b6e7 |
656 | kxchal *kxc; |
657 | buf bb; |
658 | stats *st = p_stats(kx->p); |
410c8acf |
659 | buf *b; |
660 | |
0617b6e7 |
661 | switch (kx->s) { |
662 | case KXS_CHAL: |
00e64b67 |
663 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
664 | p_name(kx->p)); ) |
0617b6e7 |
665 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
666 | buf_putmp(b, kx->c); |
667 | break; |
668 | case KXS_COMMIT: |
00e64b67 |
669 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
670 | p_name(kx->p)); ) |
0617b6e7 |
671 | kxc = kx->r[0]; |
672 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); |
673 | buf_put(b, kx->hc, HASHSZ); |
674 | buf_put(b, kxc->hc, HASHSZ); |
675 | buf_init(&bb, buf_i, sizeof(buf_i)); |
676 | buf_putmp(&bb, kxc->r); |
677 | buf_put(&bb, kxc->hswrq_out, HASHSZ); |
678 | buf_flip(&bb); |
7ed14135 |
679 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 |
680 | break; |
681 | case KXS_SWITCH: |
00e64b67 |
682 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 |
683 | p_name(kx->p)); ) |
684 | kxc = kx->r[0]; |
685 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); |
686 | buf_init(&bb, buf_i, sizeof(buf_i)); |
687 | buf_put(&bb, kxc->hswok_out, HASHSZ); |
688 | buf_flip(&bb); |
7ed14135 |
689 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 |
690 | break; |
691 | default: |
692 | abort(); |
410c8acf |
693 | } |
0617b6e7 |
694 | |
695 | if (BOK(b)) { |
696 | st->n_kxout++; |
697 | st->sz_kxout += BLEN(b); |
698 | p_txend(kx->p); |
699 | } |
700 | |
701 | if (kx->s < KXS_SWITCH) |
702 | settimer(kx, time(0) + T_RETRY); |
410c8acf |
703 | } |
704 | |
0617b6e7 |
705 | /* --- @matchreply@ --- * |
706 | * |
707 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
7ed14135 |
708 | * @unsigned ty@ = type of incoming message |
0617b6e7 |
709 | * @const octet *hc_in@ = a hash of his challenge |
710 | * @const octet *hc_out@ = a hash of my challenge (cookie) |
5d418e24 |
711 | * @mp *ck@ = his expected-reply hash (optional) |
0617b6e7 |
712 | * @buf *b@ = encrypted remainder of the packet |
713 | * |
714 | * Returns: A pointer to the challenge block if OK, or null on failure. |
715 | * |
716 | * Use: Checks a reply or switch packet, ensuring that its contents |
717 | * are sensible and correct. If they are, @*b@ is set to point |
718 | * to the remainder of the encrypted data, and the correct |
719 | * challenge is returned. |
720 | */ |
721 | |
7ed14135 |
722 | static kxchal *matchreply(keyexch *kx, unsigned ty, const octet *hc_in, |
5d418e24 |
723 | const octet *hc_out, mp *ck, buf *b) |
410c8acf |
724 | { |
0617b6e7 |
725 | kxchal *kxc; |
726 | buf bb; |
727 | mp *r = 0; |
728 | |
729 | /* --- Check the plaintext portions of the data --- */ |
730 | |
731 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
732 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, HASHSZ); |
733 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, HASHSZ); |
5d418e24 |
734 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
735 | })) |
736 | if (memcmp(hc_out, kx->hc, HASHSZ) != 0) { |
737 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
738 | goto bad; |
739 | } |
740 | if ((kxc = kxc_byhc(kx, hc_in)) == 0) { |
741 | a_warn("received reply for unknown challenge from `%s'", p_name(kx->p)); |
742 | goto bad; |
743 | } |
410c8acf |
744 | |
0617b6e7 |
745 | /* --- Maybe compute a reply for the challenge --- */ |
746 | |
747 | if (!kxc->r) { |
5d418e24 |
748 | if (!ck) { |
0617b6e7 |
749 | a_warn("unexpected switch request from `%s'", p_name(kx->p)); |
750 | goto bad; |
751 | } |
5d418e24 |
752 | if ((r = getreply(kx, kxc->c, ck)) == 0) |
0617b6e7 |
753 | goto bad; |
754 | kxc->r = r; |
755 | r = 0; |
756 | } |
757 | |
758 | /* --- Decrypt the rest of the packet --- */ |
759 | |
760 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
761 | if (ks_decrypt(kxc->ks, ty, b, &bb)) { |
0617b6e7 |
762 | a_warn("failed to decrypt reply from `%s'", p_name(kx->p)); |
763 | goto bad; |
410c8acf |
764 | } |
0617b6e7 |
765 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
766 | if ((r = buf_getmp(b)) == 0) { |
767 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
768 | goto bad; |
769 | } |
770 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
771 | trace(T_CRYPTO, "crypto: reply = %s", mpstr(r)); |
772 | })) |
773 | if (!mp_eq(r, kx->rx)) { |
774 | a_warn("incorrect reply from `%s'", p_name(kx->p)); |
775 | goto bad; |
776 | } |
777 | |
778 | /* --- Done --- */ |
779 | |
780 | mp_drop(r); |
781 | return (kxc); |
782 | |
783 | bad: |
784 | mp_drop(r); |
785 | return (0); |
410c8acf |
786 | } |
787 | |
0617b6e7 |
788 | /* --- @commit@ --- * |
410c8acf |
789 | * |
790 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
791 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf |
792 | * |
793 | * Returns: --- |
794 | * |
0617b6e7 |
795 | * Use: Commits to a particular challenge as being the `right' one, |
796 | * since a reply has arrived for it. |
410c8acf |
797 | */ |
798 | |
0617b6e7 |
799 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf |
800 | { |
0617b6e7 |
801 | unsigned i; |
410c8acf |
802 | |
0617b6e7 |
803 | for (i = 0; i < kx->nr; i++) { |
804 | if (kx->r[i] != kxc) |
805 | kxc_destroy(kx->r[i]); |
806 | } |
807 | kx->r[0] = kxc; |
808 | kx->nr = 1; |
809 | kxc_stoptimer(kxc); |
810 | ksl_link(kx->ks, kxc->ks); |
410c8acf |
811 | } |
812 | |
0617b6e7 |
813 | /* --- @doreply@ --- * |
410c8acf |
814 | * |
815 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
816 | * @buf *b@ = buffer containing packet |
410c8acf |
817 | * |
0617b6e7 |
818 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
819 | * |
0617b6e7 |
820 | * Use: Handles a reply packet. This doesn't handle the various |
821 | * switch packets: they're rather too different. |
410c8acf |
822 | */ |
823 | |
0617b6e7 |
824 | static int doreply(keyexch *kx, buf *b) |
410c8acf |
825 | { |
5d418e24 |
826 | const octet *hc_in, *hc_out; |
827 | mp *ck = 0; |
0617b6e7 |
828 | kxchal *kxc; |
829 | |
830 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { |
831 | a_warn("unexpected reply from `%s'", p_name(kx->p)); |
832 | goto bad; |
833 | } |
834 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
835 | (hc_out = buf_get(b, HASHSZ)) == 0 || |
5d418e24 |
836 | (ck = buf_getmp(b)) == 0) { |
0617b6e7 |
837 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
838 | goto bad; |
839 | } |
7ed14135 |
840 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_REPLY, |
841 | hc_in, hc_out, ck, b)) == 0) |
0617b6e7 |
842 | goto bad; |
843 | if (BLEFT(b)) { |
844 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
845 | goto bad; |
846 | } |
847 | if (kx->s == KXS_CHAL) { |
848 | commit(kx, kxc); |
849 | kx->s = KXS_COMMIT; |
850 | } |
851 | resend(kx); |
852 | return (0); |
853 | |
854 | bad: |
5d418e24 |
855 | mp_drop(ck); |
0617b6e7 |
856 | return (-1); |
410c8acf |
857 | } |
858 | |
0617b6e7 |
859 | /* --- @doswitch@ --- * |
410c8acf |
860 | * |
0617b6e7 |
861 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
862 | * @buf *b@ = pointer to buffer containing packet |
410c8acf |
863 | * |
0617b6e7 |
864 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
865 | * |
0617b6e7 |
866 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf |
867 | */ |
868 | |
0617b6e7 |
869 | static int doswitch(keyexch *kx, buf *b) |
410c8acf |
870 | { |
0617b6e7 |
871 | const octet *hc_in, *hc_out, *hswrq; |
872 | kxchal *kxc; |
410c8acf |
873 | |
0617b6e7 |
874 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
875 | (hc_out = buf_get(b, HASHSZ)) == 0) { |
876 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
877 | goto bad; |
410c8acf |
878 | } |
7ed14135 |
879 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_SWITCH, |
880 | hc_in, hc_out, 0, b)) == 0) |
0617b6e7 |
881 | goto bad; |
882 | if ((hswrq = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
883 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
884 | goto bad; |
885 | } |
886 | IF_TRACING(T_KEYEXCH, { |
887 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, HASHSZ); |
888 | }) |
889 | if (memcmp(hswrq, kxc->hswrq_in, HASHSZ) != 0) { |
890 | a_warn("incorrect switch request hash from `%s'", p_name(kx->p)); |
891 | goto bad; |
892 | } |
893 | switch (kx->s) { |
894 | case KXS_CHAL: |
895 | commit(kx, kxc); |
896 | case KXS_COMMIT: |
897 | ks_activate(kxc->ks); |
898 | settimer(kx, ks_tregen(kxc->ks)); |
899 | kx->s = KXS_SWITCH; |
900 | break; |
901 | } |
902 | resend(kx); |
903 | return (0); |
904 | |
905 | bad: |
906 | return (-1); |
410c8acf |
907 | } |
908 | |
0617b6e7 |
909 | /* --- @doswitchok@ --- * |
910 | * |
911 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
912 | * @buf *b@ = pointer to buffer containing packet |
913 | * |
914 | * Returns: Zero if OK, nonzero if the packet was rejected. |
915 | * |
916 | * Use: Handles a reply with a switch request bolted onto it. |
917 | */ |
918 | |
919 | static int doswitchok(keyexch *kx, buf *b) |
410c8acf |
920 | { |
0617b6e7 |
921 | const octet *hswok; |
922 | kxchal *kxc; |
923 | buf bb; |
410c8acf |
924 | |
0617b6e7 |
925 | if (kx->s < KXS_COMMIT) { |
926 | a_warn("unexpected switch confirmation from `%s'", p_name(kx->p)); |
927 | goto bad; |
410c8acf |
928 | } |
0617b6e7 |
929 | kxc = kx->r[0]; |
930 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
931 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, b, &bb)) { |
0617b6e7 |
932 | a_warn("failed to decrypt switch confirmation from `%s'", p_name(kx->p)); |
933 | goto bad; |
934 | } |
935 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
936 | if ((hswok = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
937 | a_warn("invalid switch confirmation from `%s'", p_name(kx->p)); |
938 | goto bad; |
939 | } |
940 | IF_TRACING(T_KEYEXCH, { |
941 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", hswok, HASHSZ); |
942 | }) |
943 | if (memcmp(hswok, kxc->hswok_in, HASHSZ) != 0) { |
944 | a_warn("incorrect switch confirmation hash from `%s'", p_name(kx->p)); |
945 | goto bad; |
946 | } |
947 | if (kx->s < KXS_SWITCH) { |
948 | ks_activate(kxc->ks); |
949 | settimer(kx, ks_tregen(kxc->ks)); |
950 | kx->s = KXS_SWITCH; |
951 | } |
952 | return (0); |
953 | |
954 | bad: |
955 | return (-1); |
956 | } |
957 | |
958 | /*----- Main code ---------------------------------------------------------*/ |
959 | |
960 | /* --- @stop@ --- * |
961 | * |
962 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
963 | * |
964 | * Returns: --- |
965 | * |
966 | * Use: Stops a key exchange dead in its tracks. Throws away all of |
967 | * the context information. The context is left in an |
968 | * inconsistent state. The only functions which understand this |
969 | * state are @kx_free@ and @kx_init@ (which cause it internally |
970 | * it), and @start@ (which expects it to be the prevailing |
971 | * state). |
972 | */ |
973 | |
974 | static void stop(keyexch *kx) |
975 | { |
976 | unsigned i; |
977 | |
00e64b67 |
978 | if (kx->f & KXF_DEAD) |
979 | return; |
980 | |
0617b6e7 |
981 | if (kx->f & KXF_TIMER) |
982 | sel_rmtimer(&kx->t); |
983 | for (i = 0; i < kx->nr; i++) |
984 | kxc_destroy(kx->r[i]); |
985 | mp_drop(kx->alpha); |
986 | mp_drop(kx->c); |
987 | mp_drop(kx->rx); |
00e64b67 |
988 | kx->t_valid = 0; |
989 | kx->f |= KXF_DEAD; |
990 | kx->f &= ~KXF_TIMER; |
0617b6e7 |
991 | } |
992 | |
993 | /* --- @start@ --- * |
994 | * |
995 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
996 | * @time_t now@ = the current time |
997 | * |
998 | * Returns: --- |
999 | * |
1000 | * Use: Starts a new key exchange with the peer. The context must be |
1001 | * in the bizarre state left by @stop@ or @kx_init@. |
1002 | */ |
1003 | |
1004 | static void start(keyexch *kx, time_t now) |
1005 | { |
1006 | HASH_CTX h; |
1007 | |
00e64b67 |
1008 | assert(kx->f & KXF_DEAD); |
1009 | |
1010 | kx->f &= ~KXF_DEAD; |
0617b6e7 |
1011 | kx->nr = 0; |
0617b6e7 |
1012 | kx->alpha = mprand_range(MP_NEW, kpriv.dp.q, &rand_global, 0); |
1013 | kx->c = mpmont_exp(&mg, MP_NEW, kpriv.dp.g, kx->alpha); |
1014 | kx->rx = mpmont_exp(&mg, MP_NEW, kx->kpub.y, kx->alpha); |
1015 | kx->s = KXS_CHAL; |
1016 | kx->t_valid = now + T_VALID; |
1017 | |
1018 | HASH_INIT(&h); |
1019 | HASH_STRING(&h, "tripe-cookie"); |
1020 | hashmp(&h, kx->c); |
1021 | HASH_DONE(&h, kx->hc); |
1022 | |
1023 | IF_TRACING(T_KEYEXCH, { |
1024 | trace(T_KEYEXCH, "keyexch: creating new challenge"); |
1025 | IF_TRACING(T_CRYPTO, { |
1026 | trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); |
1027 | trace(T_CRYPTO, "crypto: challenge = %s", mpstr(kx->c)); |
1028 | trace(T_CRYPTO, "crypto: expected response = %s", mpstr(kx->rx)); |
1029 | trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, HASHSZ); |
1030 | }) |
1031 | }) |
410c8acf |
1032 | } |
1033 | |
00e64b67 |
1034 | /* --- @checkpub@ --- * |
1035 | * |
1036 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1037 | * |
1038 | * Returns: Zero if OK, nonzero if the peer's public key has expired. |
1039 | * |
1040 | * Use: Deactivates the key-exchange until the peer acquires a new |
1041 | * public key. |
1042 | */ |
1043 | |
1044 | static int checkpub(keyexch *kx) |
1045 | { |
1046 | time_t now; |
1047 | if (kx->f & KXF_DEAD) |
1048 | return (-1); |
1049 | now = time(0); |
1050 | if (KEY_EXPIRED(now, kx->texp_kpub)) { |
1051 | stop(kx); |
1052 | a_warn("public key for `%s' has expired", p_name(kx->p)); |
1053 | dh_pubfree(&kx->kpub); |
1054 | kx->f &= ~KXF_PUBKEY; |
1055 | return (-1); |
1056 | } |
1057 | return (0); |
1058 | } |
1059 | |
0617b6e7 |
1060 | /* --- @kx_start@ --- * |
410c8acf |
1061 | * |
1062 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
1063 | * |
1064 | * Returns: --- |
1065 | * |
0617b6e7 |
1066 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1067 | * a new challenge is sent (unless the quiet timer forbids |
1068 | * this); if no exchange is in progress, one is commenced. |
410c8acf |
1069 | */ |
1070 | |
0617b6e7 |
1071 | void kx_start(keyexch *kx) |
410c8acf |
1072 | { |
1073 | time_t now = time(0); |
410c8acf |
1074 | |
00e64b67 |
1075 | if (checkpub(kx)) |
1076 | return; |
0617b6e7 |
1077 | if (!ISVALID(kx, now)) { |
1078 | stop(kx); |
1079 | start(kx, now); |
410c8acf |
1080 | } |
0617b6e7 |
1081 | resend(kx); |
1082 | } |
1083 | |
1084 | /* --- @kx_message@ --- * |
1085 | * |
1086 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1087 | * @unsigned msg@ = the message code |
1088 | * @buf *b@ = pointer to buffer containing the packet |
1089 | * |
1090 | * Returns: --- |
1091 | * |
1092 | * Use: Reads a packet containing key exchange messages and handles |
1093 | * it. |
1094 | */ |
1095 | |
1096 | void kx_message(keyexch *kx, unsigned msg, buf *b) |
1097 | { |
1098 | time_t now = time(0); |
1099 | stats *st = p_stats(kx->p); |
1100 | size_t sz = BSZ(b); |
1101 | int rc; |
1102 | |
1103 | #ifndef NTRACE |
1104 | static const char *const pkname[] = { |
1105 | "prechallenge", "cookie", "challenge", |
1106 | "reply", "switch request", "switch confirmation" |
1107 | }; |
1108 | #endif |
1109 | |
00e64b67 |
1110 | if (checkpub(kx)) |
1111 | return; |
1112 | |
0617b6e7 |
1113 | if (!ISVALID(kx, now)) { |
1114 | stop(kx); |
1115 | start(kx, now); |
410c8acf |
1116 | } |
0617b6e7 |
1117 | |
1118 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", |
1119 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) |
1120 | |
1121 | switch (msg) { |
1122 | case KX_PRECHAL: |
1123 | case KX_COOKIE: |
1124 | case KX_CHAL: |
1125 | rc = dochallenge(kx, msg, b); |
1126 | break; |
1127 | case KX_REPLY: |
1128 | rc = doreply(kx, b); |
1129 | break; |
1130 | case KX_SWITCH: |
1131 | rc = doswitch(kx, b); |
1132 | break; |
1133 | case KX_SWITCHOK: |
1134 | rc = doswitchok(kx, b); |
1135 | break; |
1136 | default: |
1137 | a_warn("unexpected key exchange message type %u from `%p'", |
1138 | p_name(kx->p)); |
1139 | rc = -1; |
1140 | break; |
410c8acf |
1141 | } |
410c8acf |
1142 | |
0617b6e7 |
1143 | if (rc) |
1144 | st->n_reject++; |
1145 | else { |
1146 | st->n_kxin++; |
1147 | st->sz_kxin += sz; |
1148 | } |
410c8acf |
1149 | } |
1150 | |
1151 | /* --- @kx_free@ --- * |
1152 | * |
1153 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1154 | * |
1155 | * Returns: --- |
1156 | * |
1157 | * Use: Frees everything in a key exchange context. |
1158 | */ |
1159 | |
1160 | void kx_free(keyexch *kx) |
1161 | { |
0617b6e7 |
1162 | stop(kx); |
00e64b67 |
1163 | if (kx->f & KXF_PUBKEY) |
1164 | dh_pubfree(&kx->kpub); |
410c8acf |
1165 | } |
1166 | |
1167 | /* --- @kx_newkeys@ --- * |
1168 | * |
1169 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1170 | * |
1171 | * Returns: --- |
1172 | * |
1173 | * Use: Informs the key exchange module that its keys may have |
1174 | * changed. If fetching the new keys fails, the peer will be |
1175 | * destroyed, we log messages and struggle along with the old |
1176 | * keys. |
1177 | */ |
1178 | |
1179 | void kx_newkeys(keyexch *kx) |
1180 | { |
1181 | dh_pub dp; |
1182 | |
00e64b67 |
1183 | if (km_getpubkey(p_name(kx->p), &dp, &kx->texp_kpub)) |
410c8acf |
1184 | return; |
00e64b67 |
1185 | if (kx->f & KXF_PUBKEY) |
1186 | dh_pubfree(&kx->kpub); |
410c8acf |
1187 | kx->kpub = dp; |
00e64b67 |
1188 | kx->f |= KXF_PUBKEY; |
1189 | if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { |
410c8acf |
1190 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1191 | p_name(kx->p)); ) |
00e64b67 |
1192 | stop(kx); |
1193 | start(kx, time(0)); |
1194 | resend(kx); |
410c8acf |
1195 | } |
1196 | } |
1197 | |
1198 | /* --- @kx_init@ --- * |
1199 | * |
1200 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1201 | * @peer *p@ = pointer to peer context |
1202 | * @keyset **ks@ = pointer to keyset list |
1203 | * |
1204 | * Returns: Zero if OK, nonzero if it failed. |
1205 | * |
1206 | * Use: Initializes a key exchange module. The module currently |
1207 | * contains no keys, and will attempt to initiate a key |
1208 | * exchange. |
1209 | */ |
1210 | |
1211 | int kx_init(keyexch *kx, peer *p, keyset **ks) |
1212 | { |
1213 | kx->ks = ks; |
1214 | kx->p = p; |
00e64b67 |
1215 | if (km_getpubkey(p_name(p), &kx->kpub, &kx->texp_kpub)) |
410c8acf |
1216 | return (-1); |
00e64b67 |
1217 | kx->f = KXF_DEAD | KXF_PUBKEY; |
0617b6e7 |
1218 | start(kx, time(0)); |
1219 | resend(kx); |
410c8acf |
1220 | return (0); |
1221 | } |
1222 | |
1223 | /*----- That's all, folks -------------------------------------------------*/ |