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410c8acf | 1 | /* -*-c-*- |
2 | * | |
3cdc3f3a | 3 | * $Id$ |
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 | ||
410c8acf | 29 | /*----- Header files ------------------------------------------------------*/ |
30 | ||
31 | #include "tripe.h" | |
32 | ||
737cc271 | 33 | /*----- Brief protocol overview -------------------------------------------* |
34 | * | |
35 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let | |
36 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote | |
37 | * application of the symmetric packet protocol to a message; let | |
38 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% | |
39 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% | |
40 | * be Bob's public key. | |
41 | * | |
42 | * At the beginning of the session, Alice chooses | |
43 | * | |
44 | * %$\rho_A \inr \{0, \ldots q - 1\}$% | |
45 | * | |
46 | * We also have: | |
47 | * | |
48 | * %$r_A = g^{\rho_A}$% Alice's challenge | |
49 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie | |
9317aa92 | 50 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, a, r_A, r_B, b^{\rho_A})$% |
737cc271 | 51 | * Alice's challenge check value |
52 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply | |
53 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% | |
54 | * Alice and Bob's shared secret key | |
55 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% | |
56 | * Alice's switch request value | |
57 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% | |
58 | * Alice's switch confirm value | |
59 | * | |
60 | * The messages are then: | |
61 | * | |
62 | * %$\cookie{kx-pre-challenge}, r_A$% | |
63 | * Initial greeting. In state @KXS_CHAL@. | |
64 | * | |
737cc271 | 65 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
66 | * Here's a full challenge for you to answer. | |
67 | * | |
28461f0e | 68 | * %$\cookie{kx-reply}, r_A, c_B, v_A, E_K(r_B^\alpha))$% |
737cc271 | 69 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
70 | * to @KXS_COMMIT@. | |
71 | * | |
3cdc3f3a | 72 | * %$\cookie{kx-switch-rq}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
737cc271 | 73 | * Reply received: here's my reply. Committed; send data; move to |
74 | * @KXS_SWITCH@. | |
75 | * | |
76 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% | |
77 | * Switch received. Committed; send data; move to @KXS_SWITCH@. | |
78 | */ | |
79 | ||
410c8acf | 80 | /*----- Tunable parameters ------------------------------------------------*/ |
81 | ||
2de0ad0f | 82 | #define T_VALID MIN(2) /* Challenge validity period */ |
83 | #define T_RETRY SEC(10) /* Challenge retransmit interval */ | |
410c8acf | 84 | |
3cdc3f3a | 85 | #define VALIDP(kx, now) ((now) < (kx)->t_valid) |
86 | ||
87 | /*----- Static tables -----------------------------------------------------*/ | |
88 | ||
89 | static const char *const pkname[] = { | |
90 | "pre-challenge", "cookie", "challenge", | |
91 | "reply", "switch-rq", "switch-ok" | |
92 | }; | |
0617b6e7 | 93 | |
94 | /*----- Various utilities -------------------------------------------------*/ | |
410c8acf | 95 | |
52c03a2a | 96 | /* --- @hashge@ --- * |
410c8acf | 97 | * |
b5c45da1 | 98 | * Arguments: @ghash *h@ = pointer to hash context |
52c03a2a | 99 | * @ge *x@ = pointer to group element |
410c8acf | 100 | * |
101 | * Returns: --- | |
102 | * | |
52c03a2a | 103 | * Use: Adds the hash of a group element to the context. Corrupts |
104 | * @buf_t@. | |
410c8acf | 105 | */ |
106 | ||
b5c45da1 | 107 | static void hashge(ghash *h, ge *x) |
410c8acf | 108 | { |
109 | buf b; | |
0617b6e7 | 110 | buf_init(&b, buf_t, sizeof(buf_t)); |
52c03a2a | 111 | G_TOBUF(gg, &b, x); |
410c8acf | 112 | assert(BOK(&b)); |
b5c45da1 | 113 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
410c8acf | 114 | } |
115 | ||
de7bd20b | 116 | /* --- @mpmask@ --- * |
5d418e24 | 117 | * |
de7bd20b MW |
118 | * Arguments: @buf *b@ = output buffer |
119 | * @mp *x@ = the plaintext integer | |
120 | * @size_t n@ = the expected size of the plaintext | |
5d418e24 | 121 | * @const octet *k@ = pointer to key material |
de7bd20b | 122 | * @size_t ksz@ = size of the key |
5d418e24 | 123 | * |
de7bd20b | 124 | * Returns: Pointer to the output. |
5d418e24 | 125 | * |
de7bd20b MW |
126 | * Use: Masks a multiprecision integer: returns %$x \xor H(k)$%, so |
127 | * it's a random oracle thing rather than an encryption thing. | |
5d418e24 | 128 | */ |
129 | ||
de7bd20b | 130 | static octet *mpmask(buf *b, mp *x, size_t n, const octet *k, size_t ksz) |
5d418e24 | 131 | { |
b5c45da1 | 132 | gcipher *mgf; |
de7bd20b | 133 | octet *p; |
5d418e24 | 134 | |
de7bd20b MW |
135 | if ((p = buf_get(b, n)) == 0) |
136 | return (0); | |
137 | mgf = GC_INIT(algs.mgf, k, ksz); | |
138 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
139 | trace(T_CRYPTO, "masking index = %s", mpstr(x)); | |
140 | trace_block(T_CRYPTO, "masking key", k, ksz); | |
141 | })) | |
142 | mp_storeb(x, buf_t, n); | |
143 | GC_ENCRYPT(mgf, buf_t, p, n); | |
144 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
145 | trace_block(T_CRYPTO, "index plaintext", buf_t, n); | |
146 | trace_block(T_CRYPTO, "masked ciphertext", p, n); | |
147 | })) | |
b5c45da1 | 148 | GC_DESTROY(mgf); |
de7bd20b | 149 | return (p); |
b5c45da1 | 150 | } |
151 | ||
de7bd20b MW |
152 | /* --- @mpunmask@ --- * |
153 | * | |
154 | * Arguments: @mp *d@ = the output integer | |
155 | * @const octet *p@ = pointer to the ciphertext | |
156 | * @size_t n@ = the size of the ciphertext | |
157 | * @const octet *k@ = pointer to key material | |
158 | * @size_t ksz@ = size of the key | |
159 | * | |
160 | * Returns: The decrypted integer, or null. | |
161 | * | |
162 | * Use: Unmasks a multiprecision integer. | |
163 | */ | |
164 | ||
165 | static mp *mpunmask(mp *d, const octet *p, size_t n, | |
166 | const octet *k, size_t ksz) | |
b5c45da1 | 167 | { |
168 | gcipher *mgf; | |
169 | ||
de7bd20b MW |
170 | mgf = GC_INIT(algs.mgf, k, ksz); |
171 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
172 | trace_block(T_CRYPTO, "unmasking key", k, ksz); | |
173 | trace_block(T_CRYPTO, "masked ciphertext", p, n); | |
174 | })) | |
175 | GC_DECRYPT(mgf, p, buf_t, n); | |
176 | d = mp_loadb(d, buf_t, n); | |
177 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
178 | trace_block(T_CRYPTO, "index plaintext", buf_t, n); | |
179 | trace(T_CRYPTO, "unmasked index = %s", mpstr(d)); | |
180 | })) | |
b5c45da1 | 181 | GC_DESTROY(mgf); |
de7bd20b MW |
182 | return (d); |
183 | } | |
184 | ||
185 | /* --- @hashcheck@ --- * | |
186 | * | |
187 | * Arguments: @ge *kpub@ = sender's public key | |
188 | * @ge *cc@ = receiver's challenge | |
189 | * @ge *c@ = sender's challenge | |
190 | * @ge *y@ = reply to sender's challenge | |
191 | * | |
192 | * Returns: Pointer to the hash value (in @buf_t@) | |
193 | * | |
194 | * Use: Computes the check-value hash, used to mask or unmask | |
195 | * indices to prove the validity of challenges. This computes | |
196 | * the masking key used in challenge check values. This is | |
197 | * really the heart of the whole thing, since it ensures that | |
198 | * the index can be recovered from the history of hashing | |
199 | * queries, which gives us (a) a proof that the authentication | |
200 | * process is zero-knowledge, and (b) a proof that the whole | |
201 | * key-exchange is deniable. | |
202 | */ | |
203 | ||
204 | static const octet *hashcheck(ge *kpub, ge *cc, ge *c, ge *y) | |
205 | { | |
206 | ghash *h = GH_INIT(algs.h); | |
207 | ||
208 | HASH_STRING(h, "tripe-expected-reply"); | |
209 | hashge(h, kpub); | |
210 | hashge(h, cc); | |
211 | hashge(h, c); | |
212 | hashge(h, y); | |
213 | GH_DONE(h, buf_t); | |
214 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
215 | trace(T_CRYPTO, "computing challenge check hash"); | |
216 | trace(T_CRYPTO, "public key = %s", gestr(gg, kpub)); | |
217 | trace(T_CRYPTO, "receiver challenge = %s", gestr(gg, cc)); | |
218 | trace(T_CRYPTO, "sender challenge = %s", gestr(gg, c)); | |
219 | trace(T_CRYPTO, "sender reply = %s", gestr(gg, y)); | |
220 | trace_block(T_CRYPTO, "hash output", buf_t, algs.hashsz); | |
221 | })) | |
222 | GH_DESTROY(h); | |
223 | return (buf_t); | |
224 | } | |
225 | ||
226 | /* --- @sendchallenge@ --- * | |
227 | * | |
228 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
229 | * @buf *b@ = output buffer for challenge | |
230 | * @ge *c@ = peer's actual challenge | |
231 | * @const octet *hc@ = peer's challenge cookie | |
232 | * | |
233 | * Returns: --- | |
234 | * | |
235 | * Use: Writes a full challenge to the message buffer. | |
236 | */ | |
237 | ||
238 | static void sendchallenge(keyexch *kx, buf *b, ge *c, const octet *hc) | |
239 | { | |
240 | G_TOBUF(gg, b, kx->c); | |
241 | buf_put(b, hc, algs.hashsz); | |
242 | mpmask(b, kx->alpha, indexsz, | |
243 | hashcheck(kpub, c, kx->c, kx->rx), algs.hashsz); | |
5d418e24 | 244 | } |
245 | ||
410c8acf | 246 | /* --- @timer@ --- * |
247 | * | |
248 | * Arguments: @struct timeval *tv@ = the current time | |
249 | * @void *v@ = pointer to key exchange context | |
250 | * | |
251 | * Returns: --- | |
252 | * | |
253 | * Use: Acts when the key exchange timer goes off. | |
254 | */ | |
255 | ||
256 | static void timer(struct timeval *tv, void *v) | |
257 | { | |
258 | keyexch *kx = v; | |
259 | kx->f &= ~KXF_TIMER; | |
260 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) | |
de014da6 | 261 | kx_start(kx, 0); |
410c8acf | 262 | } |
263 | ||
264 | /* --- @settimer@ --- * | |
265 | * | |
266 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
267 | * @time_t t@ = when to set the timer for | |
268 | * | |
269 | * Returns: --- | |
270 | * | |
271 | * Use: Sets the timer for the next key exchange attempt. | |
272 | */ | |
273 | ||
274 | static void settimer(keyexch *kx, time_t t) | |
275 | { | |
276 | struct timeval tv; | |
277 | if (kx->f & KXF_TIMER) | |
278 | sel_rmtimer(&kx->t); | |
279 | tv.tv_sec = t; | |
280 | tv.tv_usec = 0; | |
281 | sel_addtimer(&sel, &kx->t, &tv, timer, kx); | |
282 | kx->f |= KXF_TIMER; | |
283 | } | |
284 | ||
0617b6e7 | 285 | /*----- Challenge management ----------------------------------------------*/ |
286 | ||
287 | /* --- Notes on challenge management --- * | |
410c8acf | 288 | * |
0617b6e7 | 289 | * We may get multiple different replies to our key exchange; some will be |
290 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges | |
291 | * received will be added to the table and given a full response. After | |
292 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': | |
293 | * our existing challenge, followed by a hash of the sender's challenge. We | |
294 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All | |
295 | * properly-formed cookies are assigned a table slot: if none is spare, a | |
296 | * used slot is randomly selected and destroyed. A cookie always receives a | |
297 | * full reply. | |
298 | */ | |
299 | ||
300 | /* --- @kxc_destroy@ --- * | |
301 | * | |
302 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
410c8acf | 303 | * |
304 | * Returns: --- | |
305 | * | |
0617b6e7 | 306 | * Use: Disposes of a challenge block. |
410c8acf | 307 | */ |
308 | ||
0617b6e7 | 309 | static void kxc_destroy(kxchal *kxc) |
410c8acf | 310 | { |
0617b6e7 | 311 | if (kxc->f & KXF_TIMER) |
312 | sel_rmtimer(&kxc->t); | |
52c03a2a | 313 | G_DESTROY(gg, kxc->c); |
de7bd20b | 314 | G_DESTROY(gg, kxc->r); |
0617b6e7 | 315 | ks_drop(kxc->ks); |
316 | DESTROY(kxc); | |
317 | } | |
410c8acf | 318 | |
0617b6e7 | 319 | /* --- @kxc_stoptimer@ --- * |
320 | * | |
321 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
322 | * | |
323 | * Returns: --- | |
324 | * | |
325 | * Use: Stops the challenge's retry timer from sending messages. | |
326 | * Useful when the state machine is in the endgame of the | |
327 | * exchange. | |
328 | */ | |
410c8acf | 329 | |
0617b6e7 | 330 | static void kxc_stoptimer(kxchal *kxc) |
331 | { | |
332 | if (kxc->f & KXF_TIMER) | |
333 | sel_rmtimer(&kxc->t); | |
2de0ad0f | 334 | kxc->f &= ~KXF_TIMER; |
0617b6e7 | 335 | } |
410c8acf | 336 | |
0617b6e7 | 337 | /* --- @kxc_new@ --- * |
338 | * | |
339 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
0617b6e7 | 340 | * |
341 | * Returns: A pointer to the challenge block. | |
342 | * | |
343 | * Use: Returns a pointer to a new challenge block to fill in. | |
344 | */ | |
410c8acf | 345 | |
0617b6e7 | 346 | static kxchal *kxc_new(keyexch *kx) |
347 | { | |
348 | kxchal *kxc; | |
349 | unsigned i; | |
350 | ||
351 | /* --- If we're over reply threshold, discard one at random --- */ | |
352 | ||
353 | if (kx->nr < KX_NCHAL) | |
354 | i = kx->nr++; | |
355 | else { | |
356 | i = rand_global.ops->range(&rand_global, KX_NCHAL); | |
357 | kxc_destroy(kx->r[i]); | |
410c8acf | 358 | } |
359 | ||
0617b6e7 | 360 | /* --- Fill in the new structure --- */ |
410c8acf | 361 | |
0617b6e7 | 362 | kxc = CREATE(kxchal); |
52c03a2a | 363 | kxc->c = G_CREATE(gg); |
de7bd20b | 364 | kxc->r = G_CREATE(gg); |
0617b6e7 | 365 | kxc->ks = 0; |
366 | kxc->kx = kx; | |
367 | kxc->f = 0; | |
368 | kx->r[i] = kxc; | |
369 | return (kxc); | |
370 | } | |
410c8acf | 371 | |
0617b6e7 | 372 | /* --- @kxc_bychal@ --- * |
373 | * | |
374 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
52c03a2a | 375 | * @ge *c@ = challenge from remote host |
0617b6e7 | 376 | * |
377 | * Returns: Pointer to the challenge block, or null. | |
378 | * | |
379 | * Use: Finds a challenge block, given its challenge. | |
380 | */ | |
381 | ||
52c03a2a | 382 | static kxchal *kxc_bychal(keyexch *kx, ge *c) |
0617b6e7 | 383 | { |
384 | unsigned i; | |
385 | ||
386 | for (i = 0; i < kx->nr; i++) { | |
52c03a2a | 387 | if (G_EQ(gg, c, kx->r[i]->c)) |
0617b6e7 | 388 | return (kx->r[i]); |
389 | } | |
390 | return (0); | |
391 | } | |
392 | ||
393 | /* --- @kxc_byhc@ --- * | |
394 | * | |
395 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
396 | * @const octet *hc@ = challenge hash from remote host | |
397 | * | |
398 | * Returns: Pointer to the challenge block, or null. | |
399 | * | |
400 | * Use: Finds a challenge block, given a hash of its challenge. | |
401 | */ | |
410c8acf | 402 | |
0617b6e7 | 403 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
404 | { | |
405 | unsigned i; | |
406 | ||
407 | for (i = 0; i < kx->nr; i++) { | |
b5c45da1 | 408 | if (memcmp(hc, kx->r[i]->hc, algs.hashsz) == 0) |
0617b6e7 | 409 | return (kx->r[i]); |
410c8acf | 410 | } |
0617b6e7 | 411 | return (0); |
412 | } | |
413 | ||
414 | /* --- @kxc_answer@ --- * | |
415 | * | |
416 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
417 | * @kxchal *kxc@ = pointer to challenge block | |
418 | * | |
419 | * Returns: --- | |
420 | * | |
421 | * Use: Sends a reply to the remote host, according to the data in | |
422 | * this challenge block. | |
423 | */ | |
424 | ||
425 | static void kxc_answer(keyexch *kx, kxchal *kxc); | |
426 | ||
427 | static void kxc_timer(struct timeval *tv, void *v) | |
428 | { | |
429 | kxchal *kxc = v; | |
430 | kxc->f &= ~KXF_TIMER; | |
431 | kxc_answer(kxc->kx, kxc); | |
432 | } | |
433 | ||
434 | static void kxc_answer(keyexch *kx, kxchal *kxc) | |
435 | { | |
436 | stats *st = p_stats(kx->p); | |
de7bd20b | 437 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | KX_REPLY); |
0617b6e7 | 438 | struct timeval tv; |
439 | buf bb; | |
440 | ||
441 | /* --- Build the reply packet --- */ | |
442 | ||
de7bd20b MW |
443 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
444 | sendchallenge(kx, b, kxc->c, kxc->hc); | |
445 | buf_init(&bb, buf_i, sizeof(buf_i)); | |
446 | G_TORAW(gg, &bb, kxc->r); | |
447 | buf_flip(&bb); | |
448 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); | |
0617b6e7 | 449 | |
450 | /* --- Update the statistics --- */ | |
451 | ||
452 | if (BOK(b)) { | |
453 | st->n_kxout++; | |
454 | st->sz_kxout += BLEN(b); | |
455 | p_txend(kx->p); | |
456 | } | |
457 | ||
458 | /* --- Schedule another resend --- */ | |
459 | ||
460 | if (kxc->f & KXF_TIMER) | |
461 | sel_rmtimer(&kxc->t); | |
462 | gettimeofday(&tv, 0); | |
463 | tv.tv_sec += T_RETRY; | |
464 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); | |
465 | kxc->f |= KXF_TIMER; | |
466 | } | |
467 | ||
468 | /*----- Individual message handlers ---------------------------------------*/ | |
469 | ||
de7bd20b | 470 | /* --- @doprechallenge@ --- * |
0617b6e7 | 471 | * |
de7bd20b MW |
472 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
473 | * @buf *b@ = buffer containing the packet | |
0617b6e7 | 474 | * |
de7bd20b | 475 | * Returns: Zero if OK, nonzero of the packet was rejected. |
0617b6e7 | 476 | * |
de7bd20b | 477 | * Use: Processes a pre-challenge message. |
0617b6e7 | 478 | */ |
479 | ||
de7bd20b | 480 | static int doprechallenge(keyexch *kx, buf *b) |
0617b6e7 | 481 | { |
de7bd20b MW |
482 | stats *st = p_stats(kx->p); |
483 | ge *c = G_CREATE(gg); | |
b5c45da1 | 484 | ghash *h; |
0617b6e7 | 485 | |
de7bd20b MW |
486 | /* --- Ensure that we're in a sensible state --- */ |
487 | ||
488 | if (kx->s != KXS_CHAL) { | |
489 | a_warn("KX", "?PEER", kx->p, "unexpected", "pre-challenge", A_END); | |
490 | goto bad; | |
491 | } | |
492 | ||
493 | /* --- Unpack the packet --- */ | |
494 | ||
495 | if (G_FROMBUF(gg, b, c) || BLEFT(b)) | |
496 | goto bad; | |
b5c45da1 | 497 | |
0617b6e7 | 498 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
de7bd20b | 499 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); |
0617b6e7 | 500 | })) |
de7bd20b MW |
501 | |
502 | /* --- Send out a full challenge by return --- */ | |
503 | ||
504 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_CHAL); | |
505 | h = GH_INIT(algs.h); | |
506 | HASH_STRING(h, "tripe-cookie"); | |
507 | hashge(h, c); | |
508 | sendchallenge(kx, b, c, GH_DONE(h, 0)); | |
b5c45da1 | 509 | GH_DESTROY(h); |
de7bd20b MW |
510 | st->n_kxout++; |
511 | st->sz_kxout += BLEN(b); | |
512 | p_txend(kx->p); | |
513 | ||
514 | /* --- Done --- */ | |
515 | ||
516 | G_DESTROY(gg, c); | |
517 | return (0); | |
518 | ||
519 | bad: | |
520 | if (c) G_DESTROY(gg, c); | |
521 | return (-1); | |
0617b6e7 | 522 | } |
523 | ||
de7bd20b | 524 | /* --- @respond@ --- * |
0617b6e7 | 525 | * |
526 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
de7bd20b | 527 | * @unsigned msg@ = message code for this packet |
0617b6e7 | 528 | * @buf *b@ = buffer containing the packet |
529 | * | |
de7bd20b | 530 | * Returns: Key-exchange challenge block, or null. |
0617b6e7 | 531 | * |
de7bd20b MW |
532 | * Use: Computes a response for the given challenge, entering it into |
533 | * a challenge block and so on. | |
0617b6e7 | 534 | */ |
535 | ||
de7bd20b | 536 | static kxchal *respond(keyexch *kx, unsigned msg, buf *b) |
0617b6e7 | 537 | { |
52c03a2a | 538 | ge *c = G_CREATE(gg); |
de7bd20b MW |
539 | ge *r = G_CREATE(gg); |
540 | ge *cc = G_CREATE(gg); | |
541 | const octet *hc, *ck; | |
542 | size_t x, y, z; | |
543 | mp *cv = 0; | |
0617b6e7 | 544 | kxchal *kxc; |
de7bd20b MW |
545 | ghash *h = 0; |
546 | buf bb; | |
547 | int ok; | |
0617b6e7 | 548 | |
549 | /* --- Unpack the packet --- */ | |
550 | ||
52c03a2a | 551 | if (G_FROMBUF(gg, b, c) || |
de7bd20b MW |
552 | (hc = buf_get(b, algs.hashsz)) == 0 || |
553 | (ck = buf_get(b, indexsz)) == 0) { | |
f43df819 | 554 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 555 | goto bad; |
556 | } | |
0617b6e7 | 557 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a | 558 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); |
de7bd20b MW |
559 | trace_block(T_CRYPTO, "crypto: cookie", hc, algs.hashsz); |
560 | trace_block(T_CRYPTO, "crypto: check-value", ck, indexsz); | |
0617b6e7 | 561 | })) |
562 | ||
0617b6e7 | 563 | /* --- Discard a packet with an invalid cookie --- */ |
564 | ||
b5c45da1 | 565 | if (hc && memcmp(hc, kx->hc, algs.hashsz) != 0) { |
f43df819 | 566 | a_warn("KX", "?PEER", "incorrect", "cookie", A_END); |
0617b6e7 | 567 | goto bad; |
568 | } | |
569 | ||
de7bd20b MW |
570 | /* --- Recover the check value and verify it --- * |
571 | * | |
572 | * To avoid recomputation on replays, we store a hash of the `right' | |
573 | * value. The `correct' value is unique, so this is right. | |
410c8acf | 574 | * |
de7bd20b | 575 | * This will also find a challenge block and, if necessary, populate it. |
410c8acf | 576 | */ |
577 | ||
de7bd20b MW |
578 | if ((kxc = kxc_bychal(kx, c)) != 0) { |
579 | h = GH_INIT(algs.h); | |
580 | HASH_STRING(h, "tripe-check-hash"); | |
581 | GH_HASH(h, ck, indexsz); | |
582 | ok = !memcmp(kxc->ck, GH_DONE(h, 0), algs.hashsz); | |
583 | GH_DESTROY(h); | |
584 | if (!ok) goto badcheck; | |
585 | } else { | |
586 | ||
587 | /* --- Compute the reply, and check the magic --- */ | |
588 | ||
589 | G_EXP(gg, r, c, kpriv); | |
590 | cv = mpunmask(MP_NEW, ck, indexsz, | |
591 | hashcheck(kx->kpub, kx->c, c, r), algs.hashsz); | |
592 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
593 | trace(T_CRYPTO, "crypto: computed reply = %s", gestr(gg, r)); | |
594 | trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(cv)); | |
595 | })) | |
596 | if (MP_CMP(cv, >, gg->r) || | |
597 | (G_EXP(gg, cc, gg->g, cv), !G_EQ(gg, c, cc))) | |
598 | goto badcheck; | |
599 | ||
600 | /* --- Fill in a new challenge block --- */ | |
601 | ||
602 | kxc = kxc_new(kx); | |
52c03a2a | 603 | G_COPY(gg, kxc->c, c); |
de7bd20b | 604 | G_COPY(gg, kxc->r, r); |
0617b6e7 | 605 | |
de7bd20b MW |
606 | h = GH_INIT(algs.h); |
607 | HASH_STRING(h, "tripe-check-hash"); | |
608 | GH_HASH(h, ck, indexsz); | |
609 | GH_DONE(h, kxc->hc); | |
610 | GH_DESTROY(h); | |
0617b6e7 | 611 | |
b5c45da1 | 612 | h = GH_INIT(algs.h); |
613 | HASH_STRING(h, "tripe-cookie"); | |
614 | hashge(h, kxc->c); | |
615 | GH_DONE(h, kxc->hc); | |
616 | GH_DESTROY(h); | |
617 | ||
618 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
619 | trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, algs.hashsz); | |
620 | })) | |
0617b6e7 | 621 | |
0617b6e7 | 622 | /* --- Work out the shared key --- */ |
623 | ||
52c03a2a | 624 | G_EXP(gg, r, c, kx->alpha); |
b5c45da1 | 625 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
626 | trace(T_CRYPTO, "crypto: shared secret = %s", gestr(gg, r)); | |
627 | })) | |
0617b6e7 | 628 | |
629 | /* --- Compute the switch messages --- */ | |
630 | ||
b5c45da1 | 631 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); |
632 | hashge(h, kx->c); hashge(h, kxc->c); | |
633 | GH_DONE(h, kxc->hswrq_out); GH_DESTROY(h); | |
634 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); | |
635 | hashge(h, kx->c); hashge(h, kxc->c); | |
636 | GH_DONE(h, kxc->hswok_out); GH_DESTROY(h); | |
0617b6e7 | 637 | |
b5c45da1 | 638 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); |
639 | hashge(h, kxc->c); hashge(h, kx->c); | |
640 | GH_DONE(h, kxc->hswrq_in); GH_DESTROY(h); | |
641 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); | |
642 | hashge(h, kxc->c); hashge(h, kx->c); | |
643 | GH_DONE(h, kxc->hswok_in); GH_DESTROY(h); | |
0617b6e7 | 644 | |
645 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
0617b6e7 | 646 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
b5c45da1 | 647 | kxc->hswrq_out, algs.hashsz); |
0617b6e7 | 648 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
b5c45da1 | 649 | kxc->hswok_out, algs.hashsz); |
0617b6e7 | 650 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
b5c45da1 | 651 | kxc->hswrq_in, algs.hashsz); |
0617b6e7 | 652 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
b5c45da1 | 653 | kxc->hswok_in, algs.hashsz); |
0617b6e7 | 654 | })) |
655 | ||
656 | /* --- Create a new symmetric keyset --- */ | |
657 | ||
de7bd20b MW |
658 | buf_init(&bb, buf_o, sizeof(buf_o)); |
659 | G_TOBUF(gg, &bb, kx->c); x = BLEN(&bb); | |
660 | G_TOBUF(gg, &bb, kxc->c); y = BLEN(&bb); | |
661 | G_TOBUF(gg, &bb, r); z = BLEN(&bb); | |
662 | assert(BOK(&bb)); | |
0617b6e7 | 663 | |
de7bd20b | 664 | kxc->ks = ks_gen(BBASE(&bb), x, y, z, kx->p); |
410c8acf | 665 | } |
666 | ||
de7bd20b MW |
667 | G_DESTROY(gg, c); |
668 | G_DESTROY(gg, cc); | |
669 | G_DESTROY(gg, r); | |
670 | mp_drop(cv); | |
671 | return (kxc); | |
410c8acf | 672 | |
de7bd20b MW |
673 | badcheck: |
674 | a_warn("KX", "?PEER", kx->p, "bad-expected-reply-log", A_END); | |
675 | goto bad; | |
676 | bad: | |
677 | G_DESTROY(gg, c); | |
678 | G_DESTROY(gg, cc); | |
679 | G_DESTROY(gg, r); | |
680 | mp_drop(cv); | |
681 | return (0); | |
682 | } | |
0617b6e7 | 683 | |
de7bd20b MW |
684 | /* --- @dochallenge@ --- * |
685 | * | |
686 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
687 | * @unsigned msg@ = message code for the packet | |
688 | * @buf *b@ = buffer containing the packet | |
689 | * | |
690 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
691 | * | |
692 | * Use: Processes a packet containing a challenge. | |
693 | */ | |
0617b6e7 | 694 | |
de7bd20b MW |
695 | static int dochallenge(keyexch *kx, buf *b) |
696 | { | |
697 | kxchal *kxc; | |
0617b6e7 | 698 | |
de7bd20b MW |
699 | if (kx->s != KXS_CHAL) { |
700 | a_warn("KX", "?PEER", kx->p, "unexpected", "challenge", A_END); | |
701 | goto bad; | |
702 | } | |
703 | if ((kxc = respond(kx, KX_CHAL, b)) == 0) | |
704 | goto bad; | |
705 | if (BLEFT(b)) { | |
706 | a_warn("KX", "?PEER", kx->p, "invalid", "challenge", A_END); | |
707 | goto bad; | |
708 | } | |
709 | kxc_answer(kx, kxc); | |
0617b6e7 | 710 | return (0); |
711 | ||
712 | bad: | |
0617b6e7 | 713 | return (-1); |
410c8acf | 714 | } |
715 | ||
0617b6e7 | 716 | /* --- @resend@ --- * |
410c8acf | 717 | * |
718 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
410c8acf | 719 | * |
720 | * Returns: --- | |
721 | * | |
0617b6e7 | 722 | * Use: Sends the next message for a key exchange. |
410c8acf | 723 | */ |
724 | ||
0617b6e7 | 725 | static void resend(keyexch *kx) |
410c8acf | 726 | { |
0617b6e7 | 727 | kxchal *kxc; |
728 | buf bb; | |
729 | stats *st = p_stats(kx->p); | |
410c8acf | 730 | buf *b; |
731 | ||
0617b6e7 | 732 | switch (kx->s) { |
733 | case KXS_CHAL: | |
00e64b67 | 734 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
735 | p_name(kx->p)); ) | |
0617b6e7 | 736 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
52c03a2a | 737 | G_TOBUF(gg, b, kx->c); |
0617b6e7 | 738 | break; |
739 | case KXS_COMMIT: | |
00e64b67 | 740 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
741 | p_name(kx->p)); ) | |
0617b6e7 | 742 | kxc = kx->r[0]; |
743 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); | |
b5c45da1 | 744 | buf_put(b, kx->hc, algs.hashsz); |
745 | buf_put(b, kxc->hc, algs.hashsz); | |
0617b6e7 | 746 | buf_init(&bb, buf_i, sizeof(buf_i)); |
de7bd20b | 747 | G_TORAW(gg, &bb, kxc->r); |
b5c45da1 | 748 | buf_put(&bb, kxc->hswrq_out, algs.hashsz); |
0617b6e7 | 749 | buf_flip(&bb); |
7ed14135 | 750 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 | 751 | break; |
752 | case KXS_SWITCH: | |
00e64b67 | 753 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 | 754 | p_name(kx->p)); ) |
755 | kxc = kx->r[0]; | |
756 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); | |
757 | buf_init(&bb, buf_i, sizeof(buf_i)); | |
b5c45da1 | 758 | buf_put(&bb, kxc->hswok_out, algs.hashsz); |
0617b6e7 | 759 | buf_flip(&bb); |
7ed14135 | 760 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 | 761 | break; |
762 | default: | |
763 | abort(); | |
410c8acf | 764 | } |
0617b6e7 | 765 | |
766 | if (BOK(b)) { | |
767 | st->n_kxout++; | |
768 | st->sz_kxout += BLEN(b); | |
769 | p_txend(kx->p); | |
770 | } | |
771 | ||
772 | if (kx->s < KXS_SWITCH) | |
773 | settimer(kx, time(0) + T_RETRY); | |
410c8acf | 774 | } |
775 | ||
de7bd20b | 776 | /* --- @decryptrest@ --- * |
0617b6e7 | 777 | * |
778 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de7bd20b MW |
779 | * @kxchal *kxc@ = pointer to challenge block |
780 | * @unsigned msg@ = type of incoming message | |
0617b6e7 | 781 | * @buf *b@ = encrypted remainder of the packet |
782 | * | |
de7bd20b | 783 | * Returns: Zero if OK, nonzero on some kind of error. |
0617b6e7 | 784 | * |
de7bd20b MW |
785 | * Use: Decrypts the remainder of the packet, and points @b@ at the |
786 | * recovered plaintext. | |
0617b6e7 | 787 | */ |
788 | ||
de7bd20b | 789 | static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b) |
410c8acf | 790 | { |
0617b6e7 | 791 | buf bb; |
0617b6e7 | 792 | |
de7bd20b MW |
793 | buf_init(&bb, buf_o, sizeof(buf_o)); |
794 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | msg, b, &bb)) { | |
795 | a_warn("KX", "?PEER", kx->p, "decrypt-failed", "%s", pkname[msg], A_END); | |
796 | return (-1); | |
0617b6e7 | 797 | } |
de7bd20b MW |
798 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
799 | return (0); | |
800 | } | |
410c8acf | 801 | |
de7bd20b MW |
802 | /* --- @checkresponse@ --- * |
803 | * | |
804 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
805 | * @unsigned msg@ = type of incoming message | |
806 | * @buf *b@ = decrypted remainder of the packet | |
807 | * | |
808 | * Returns: Zero if OK, nonzero on some kind of error. | |
809 | * | |
810 | * Use: Checks a reply or switch packet, ensuring that its response | |
811 | * is correct. | |
812 | */ | |
0617b6e7 | 813 | |
de7bd20b MW |
814 | static int checkresponse(keyexch *kx, unsigned msg, buf *b) |
815 | { | |
816 | ge *r = G_CREATE(gg); | |
0617b6e7 | 817 | |
5251b2e9 | 818 | if (G_FROMRAW(gg, b, r)) { |
de7bd20b | 819 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 820 | goto bad; |
821 | } | |
822 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
52c03a2a | 823 | trace(T_CRYPTO, "crypto: reply = %s", gestr(gg, r)); |
0617b6e7 | 824 | })) |
52c03a2a | 825 | if (!G_EQ(gg, r, kx->rx)) { |
de7bd20b | 826 | a_warn("KX", "?PEER", kx->p, "incorrect", "response", A_END); |
0617b6e7 | 827 | goto bad; |
828 | } | |
829 | ||
52c03a2a | 830 | G_DESTROY(gg, r); |
de7bd20b | 831 | return (0); |
0617b6e7 | 832 | |
833 | bad: | |
de7bd20b MW |
834 | G_DESTROY(gg, r); |
835 | return (-1); | |
410c8acf | 836 | } |
837 | ||
0617b6e7 | 838 | /* --- @commit@ --- * |
410c8acf | 839 | * |
840 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 841 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf | 842 | * |
843 | * Returns: --- | |
844 | * | |
0617b6e7 | 845 | * Use: Commits to a particular challenge as being the `right' one, |
846 | * since a reply has arrived for it. | |
410c8acf | 847 | */ |
848 | ||
0617b6e7 | 849 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf | 850 | { |
0617b6e7 | 851 | unsigned i; |
410c8acf | 852 | |
0617b6e7 | 853 | for (i = 0; i < kx->nr; i++) { |
854 | if (kx->r[i] != kxc) | |
855 | kxc_destroy(kx->r[i]); | |
856 | } | |
857 | kx->r[0] = kxc; | |
858 | kx->nr = 1; | |
859 | kxc_stoptimer(kxc); | |
860 | ksl_link(kx->ks, kxc->ks); | |
410c8acf | 861 | } |
862 | ||
0617b6e7 | 863 | /* --- @doreply@ --- * |
410c8acf | 864 | * |
865 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 866 | * @buf *b@ = buffer containing packet |
410c8acf | 867 | * |
0617b6e7 | 868 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 869 | * |
0617b6e7 | 870 | * Use: Handles a reply packet. This doesn't handle the various |
871 | * switch packets: they're rather too different. | |
410c8acf | 872 | */ |
873 | ||
0617b6e7 | 874 | static int doreply(keyexch *kx, buf *b) |
410c8acf | 875 | { |
0617b6e7 | 876 | kxchal *kxc; |
877 | ||
878 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { | |
f43df819 | 879 | a_warn("KX", "?PEER", kx->p, "unexpected", "reply", A_END); |
0617b6e7 | 880 | goto bad; |
881 | } | |
de7bd20b MW |
882 | if ((kxc = respond(kx, KX_REPLY, b)) == 0 || |
883 | decryptrest(kx, kxc, KX_REPLY, b) || | |
884 | checkresponse(kx, KX_REPLY, b)) | |
0617b6e7 | 885 | goto bad; |
886 | if (BLEFT(b)) { | |
f43df819 | 887 | a_warn("KX", "?PEER", kx->p, "invalid", "reply", A_END); |
0617b6e7 | 888 | goto bad; |
de7bd20b | 889 | } |
0617b6e7 | 890 | if (kx->s == KXS_CHAL) { |
891 | commit(kx, kxc); | |
892 | kx->s = KXS_COMMIT; | |
893 | } | |
894 | resend(kx); | |
895 | return (0); | |
896 | ||
897 | bad: | |
898 | return (-1); | |
410c8acf | 899 | } |
900 | ||
3cdc3f3a | 901 | /* --- @kxfinish@ --- * |
902 | * | |
903 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
904 | * | |
905 | * Returns: --- | |
906 | * | |
907 | * Use: Sets everything up following a successful key exchange. | |
908 | */ | |
909 | ||
910 | static void kxfinish(keyexch *kx) | |
911 | { | |
912 | kxchal *kxc = kx->r[0]; | |
913 | ks_activate(kxc->ks); | |
914 | settimer(kx, ks_tregen(kxc->ks)); | |
915 | kx->s = KXS_SWITCH; | |
f43df819 | 916 | a_notify("KXDONE", "?PEER", kx->p, A_END); |
3cdc3f3a | 917 | p_stats(kx->p)->t_kx = time(0); |
918 | } | |
919 | ||
0617b6e7 | 920 | /* --- @doswitch@ --- * |
410c8acf | 921 | * |
0617b6e7 | 922 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
923 | * @buf *b@ = pointer to buffer containing packet | |
410c8acf | 924 | * |
0617b6e7 | 925 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 926 | * |
0617b6e7 | 927 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf | 928 | */ |
929 | ||
0617b6e7 | 930 | static int doswitch(keyexch *kx, buf *b) |
410c8acf | 931 | { |
0617b6e7 | 932 | const octet *hc_in, *hc_out, *hswrq; |
933 | kxchal *kxc; | |
410c8acf | 934 | |
b5c45da1 | 935 | if ((hc_in = buf_get(b, algs.hashsz)) == 0 || |
936 | (hc_out = buf_get(b, algs.hashsz)) == 0) { | |
f43df819 | 937 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); |
0617b6e7 | 938 | goto bad; |
410c8acf | 939 | } |
de7bd20b MW |
940 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
941 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, algs.hashsz); | |
942 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, algs.hashsz); | |
943 | })) | |
944 | if ((kxc = kxc_byhc(kx, hc_in)) == 0 || | |
945 | memcmp(hc_out, kx->hc, algs.hashsz) != 0) { | |
946 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); | |
947 | goto bad; | |
948 | } | |
949 | if (decryptrest(kx, kxc, KX_SWITCH, b) || | |
950 | checkresponse(kx, KX_SWITCH, b)) | |
0617b6e7 | 951 | goto bad; |
b5c45da1 | 952 | if ((hswrq = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { |
f43df819 | 953 | a_warn("KX", "?PEER", "invalid", "switch-rq", A_END); |
0617b6e7 | 954 | goto bad; |
955 | } | |
956 | IF_TRACING(T_KEYEXCH, { | |
b5c45da1 | 957 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, algs.hashsz); |
0617b6e7 | 958 | }) |
b5c45da1 | 959 | if (memcmp(hswrq, kxc->hswrq_in, algs.hashsz) != 0) { |
f43df819 | 960 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); |
0617b6e7 | 961 | goto bad; |
962 | } | |
de7bd20b MW |
963 | if (kx->s == KXS_CHAL) |
964 | commit(kx, kxc); | |
965 | if (kx->s < KXS_SWITCH) | |
966 | kxfinish(kx); | |
0617b6e7 | 967 | resend(kx); |
968 | return (0); | |
969 | ||
970 | bad: | |
971 | return (-1); | |
410c8acf | 972 | } |
973 | ||
0617b6e7 | 974 | /* --- @doswitchok@ --- * |
975 | * | |
976 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
977 | * @buf *b@ = pointer to buffer containing packet | |
978 | * | |
979 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
980 | * | |
981 | * Use: Handles a reply with a switch request bolted onto it. | |
982 | */ | |
983 | ||
984 | static int doswitchok(keyexch *kx, buf *b) | |
410c8acf | 985 | { |
0617b6e7 | 986 | const octet *hswok; |
987 | kxchal *kxc; | |
988 | buf bb; | |
410c8acf | 989 | |
0617b6e7 | 990 | if (kx->s < KXS_COMMIT) { |
f43df819 | 991 | a_warn("KX", "?PEER", kx->p, "unexpected", "switch-ok", A_END); |
0617b6e7 | 992 | goto bad; |
410c8acf | 993 | } |
0617b6e7 | 994 | kxc = kx->r[0]; |
995 | buf_init(&bb, buf_o, sizeof(buf_o)); | |
de7bd20b | 996 | if (decryptrest(kx, kxc, KX_SWITCHOK, b)) |
0617b6e7 | 997 | goto bad; |
b5c45da1 | 998 | if ((hswok = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { |
f43df819 | 999 | a_warn("KX", "?PEER", "invalid", "switch-ok", A_END); |
0617b6e7 | 1000 | goto bad; |
1001 | } | |
1002 | IF_TRACING(T_KEYEXCH, { | |
b5c45da1 | 1003 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", |
1004 | hswok, algs.hashsz); | |
0617b6e7 | 1005 | }) |
b5c45da1 | 1006 | if (memcmp(hswok, kxc->hswok_in, algs.hashsz) != 0) { |
f43df819 | 1007 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-ok", A_END); |
0617b6e7 | 1008 | goto bad; |
1009 | } | |
3cdc3f3a | 1010 | if (kx->s < KXS_SWITCH) |
1011 | kxfinish(kx); | |
0617b6e7 | 1012 | return (0); |
1013 | ||
1014 | bad: | |
1015 | return (-1); | |
1016 | } | |
1017 | ||
1018 | /*----- Main code ---------------------------------------------------------*/ | |
1019 | ||
1020 | /* --- @stop@ --- * | |
1021 | * | |
1022 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1023 | * | |
1024 | * Returns: --- | |
1025 | * | |
1026 | * Use: Stops a key exchange dead in its tracks. Throws away all of | |
1027 | * the context information. The context is left in an | |
1028 | * inconsistent state. The only functions which understand this | |
1029 | * state are @kx_free@ and @kx_init@ (which cause it internally | |
1030 | * it), and @start@ (which expects it to be the prevailing | |
1031 | * state). | |
1032 | */ | |
1033 | ||
1034 | static void stop(keyexch *kx) | |
1035 | { | |
1036 | unsigned i; | |
1037 | ||
00e64b67 | 1038 | if (kx->f & KXF_DEAD) |
1039 | return; | |
1040 | ||
0617b6e7 | 1041 | if (kx->f & KXF_TIMER) |
1042 | sel_rmtimer(&kx->t); | |
1043 | for (i = 0; i < kx->nr; i++) | |
1044 | kxc_destroy(kx->r[i]); | |
1045 | mp_drop(kx->alpha); | |
52c03a2a | 1046 | G_DESTROY(gg, kx->c); |
1047 | G_DESTROY(gg, kx->rx); | |
00e64b67 | 1048 | kx->t_valid = 0; |
1049 | kx->f |= KXF_DEAD; | |
1050 | kx->f &= ~KXF_TIMER; | |
0617b6e7 | 1051 | } |
1052 | ||
1053 | /* --- @start@ --- * | |
1054 | * | |
1055 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1056 | * @time_t now@ = the current time | |
1057 | * | |
1058 | * Returns: --- | |
1059 | * | |
1060 | * Use: Starts a new key exchange with the peer. The context must be | |
1061 | * in the bizarre state left by @stop@ or @kx_init@. | |
1062 | */ | |
1063 | ||
1064 | static void start(keyexch *kx, time_t now) | |
1065 | { | |
b5c45da1 | 1066 | ghash *h; |
0617b6e7 | 1067 | |
00e64b67 | 1068 | assert(kx->f & KXF_DEAD); |
1069 | ||
1070 | kx->f &= ~KXF_DEAD; | |
0617b6e7 | 1071 | kx->nr = 0; |
52c03a2a | 1072 | kx->alpha = mprand_range(MP_NEW, gg->r, &rand_global, 0); |
1073 | kx->c = G_CREATE(gg); G_EXP(gg, kx->c, gg->g, kx->alpha); | |
1074 | kx->rx = G_CREATE(gg); G_EXP(gg, kx->rx, kx->kpub, kx->alpha); | |
0617b6e7 | 1075 | kx->s = KXS_CHAL; |
1076 | kx->t_valid = now + T_VALID; | |
1077 | ||
b5c45da1 | 1078 | h = GH_INIT(algs.h); |
1079 | HASH_STRING(h, "tripe-cookie"); | |
1080 | hashge(h, kx->c); | |
1081 | GH_DONE(h, kx->hc); | |
1082 | GH_DESTROY(h); | |
0617b6e7 | 1083 | |
1084 | IF_TRACING(T_KEYEXCH, { | |
1085 | trace(T_KEYEXCH, "keyexch: creating new challenge"); | |
1086 | IF_TRACING(T_CRYPTO, { | |
1087 | trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); | |
52c03a2a | 1088 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, kx->c)); |
1089 | trace(T_CRYPTO, "crypto: expected response = %s", gestr(gg, kx->rx)); | |
b5c45da1 | 1090 | trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, algs.hashsz); |
0617b6e7 | 1091 | }) |
1092 | }) | |
410c8acf | 1093 | } |
1094 | ||
00e64b67 | 1095 | /* --- @checkpub@ --- * |
1096 | * | |
1097 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1098 | * | |
1099 | * Returns: Zero if OK, nonzero if the peer's public key has expired. | |
1100 | * | |
1101 | * Use: Deactivates the key-exchange until the peer acquires a new | |
1102 | * public key. | |
1103 | */ | |
1104 | ||
1105 | static int checkpub(keyexch *kx) | |
1106 | { | |
1107 | time_t now; | |
1108 | if (kx->f & KXF_DEAD) | |
1109 | return (-1); | |
1110 | now = time(0); | |
1111 | if (KEY_EXPIRED(now, kx->texp_kpub)) { | |
1112 | stop(kx); | |
f43df819 | 1113 | a_warn("KX", "?PEER", kx->p, "public-key-expired", A_END); |
52c03a2a | 1114 | G_COPY(gg, kx->kpub, gg->i); |
00e64b67 | 1115 | kx->f &= ~KXF_PUBKEY; |
1116 | return (-1); | |
1117 | } | |
1118 | return (0); | |
1119 | } | |
1120 | ||
0617b6e7 | 1121 | /* --- @kx_start@ --- * |
410c8acf | 1122 | * |
1123 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de014da6 | 1124 | * @int forcep@ = nonzero to ignore the quiet timer |
410c8acf | 1125 | * |
1126 | * Returns: --- | |
1127 | * | |
0617b6e7 | 1128 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1129 | * a new challenge is sent (unless the quiet timer forbids | |
1130 | * this); if no exchange is in progress, one is commenced. | |
410c8acf | 1131 | */ |
1132 | ||
de014da6 | 1133 | void kx_start(keyexch *kx, int forcep) |
410c8acf | 1134 | { |
1135 | time_t now = time(0); | |
410c8acf | 1136 | |
00e64b67 | 1137 | if (checkpub(kx)) |
1138 | return; | |
de014da6 | 1139 | if (forcep || !VALIDP(kx, now)) { |
0617b6e7 | 1140 | stop(kx); |
1141 | start(kx, now); | |
f43df819 | 1142 | a_notify("KXSTART", "?PEER", kx->p, A_END); |
410c8acf | 1143 | } |
0617b6e7 | 1144 | resend(kx); |
1145 | } | |
1146 | ||
1147 | /* --- @kx_message@ --- * | |
1148 | * | |
1149 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1150 | * @unsigned msg@ = the message code | |
1151 | * @buf *b@ = pointer to buffer containing the packet | |
1152 | * | |
1153 | * Returns: --- | |
1154 | * | |
1155 | * Use: Reads a packet containing key exchange messages and handles | |
1156 | * it. | |
1157 | */ | |
1158 | ||
1159 | void kx_message(keyexch *kx, unsigned msg, buf *b) | |
1160 | { | |
1161 | time_t now = time(0); | |
1162 | stats *st = p_stats(kx->p); | |
1163 | size_t sz = BSZ(b); | |
1164 | int rc; | |
1165 | ||
00e64b67 | 1166 | if (checkpub(kx)) |
1167 | return; | |
1168 | ||
3cdc3f3a | 1169 | if (!VALIDP(kx, now)) { |
0617b6e7 | 1170 | stop(kx); |
1171 | start(kx, now); | |
410c8acf | 1172 | } |
0617b6e7 | 1173 | |
1174 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", | |
1175 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) | |
1176 | ||
1177 | switch (msg) { | |
1178 | case KX_PRECHAL: | |
de7bd20b MW |
1179 | rc = doprechallenge(kx, b); |
1180 | break; | |
0617b6e7 | 1181 | case KX_CHAL: |
de7bd20b | 1182 | rc = dochallenge(kx, b); |
0617b6e7 | 1183 | break; |
1184 | case KX_REPLY: | |
1185 | rc = doreply(kx, b); | |
1186 | break; | |
1187 | case KX_SWITCH: | |
1188 | rc = doswitch(kx, b); | |
1189 | break; | |
1190 | case KX_SWITCHOK: | |
1191 | rc = doswitchok(kx, b); | |
1192 | break; | |
1193 | default: | |
f43df819 | 1194 | a_warn("KX", "?PEER", kx->p, "unknown-message", "0x%02x", msg, A_END); |
0617b6e7 | 1195 | rc = -1; |
1196 | break; | |
410c8acf | 1197 | } |
410c8acf | 1198 | |
0617b6e7 | 1199 | if (rc) |
1200 | st->n_reject++; | |
1201 | else { | |
1202 | st->n_kxin++; | |
1203 | st->sz_kxin += sz; | |
1204 | } | |
410c8acf | 1205 | } |
1206 | ||
1207 | /* --- @kx_free@ --- * | |
1208 | * | |
1209 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1210 | * | |
1211 | * Returns: --- | |
1212 | * | |
1213 | * Use: Frees everything in a key exchange context. | |
1214 | */ | |
1215 | ||
1216 | void kx_free(keyexch *kx) | |
1217 | { | |
0617b6e7 | 1218 | stop(kx); |
52c03a2a | 1219 | G_DESTROY(gg, kx->kpub); |
410c8acf | 1220 | } |
1221 | ||
1222 | /* --- @kx_newkeys@ --- * | |
1223 | * | |
1224 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1225 | * | |
1226 | * Returns: --- | |
1227 | * | |
1228 | * Use: Informs the key exchange module that its keys may have | |
1229 | * changed. If fetching the new keys fails, the peer will be | |
1230 | * destroyed, we log messages and struggle along with the old | |
1231 | * keys. | |
1232 | */ | |
1233 | ||
1234 | void kx_newkeys(keyexch *kx) | |
1235 | { | |
52c03a2a | 1236 | if (km_getpubkey(p_name(kx->p), kx->kpub, &kx->texp_kpub)) |
410c8acf | 1237 | return; |
00e64b67 | 1238 | kx->f |= KXF_PUBKEY; |
1239 | if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { | |
410c8acf | 1240 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1241 | p_name(kx->p)); ) | |
00e64b67 | 1242 | stop(kx); |
1243 | start(kx, time(0)); | |
1244 | resend(kx); | |
410c8acf | 1245 | } |
1246 | } | |
1247 | ||
1248 | /* --- @kx_init@ --- * | |
1249 | * | |
1250 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1251 | * @peer *p@ = pointer to peer context | |
1252 | * @keyset **ks@ = pointer to keyset list | |
1253 | * | |
1254 | * Returns: Zero if OK, nonzero if it failed. | |
1255 | * | |
1256 | * Use: Initializes a key exchange module. The module currently | |
1257 | * contains no keys, and will attempt to initiate a key | |
1258 | * exchange. | |
1259 | */ | |
1260 | ||
1261 | int kx_init(keyexch *kx, peer *p, keyset **ks) | |
1262 | { | |
1263 | kx->ks = ks; | |
1264 | kx->p = p; | |
52c03a2a | 1265 | kx->kpub = G_CREATE(gg); |
1266 | if (km_getpubkey(p_name(p), kx->kpub, &kx->texp_kpub)) { | |
1267 | G_DESTROY(gg, kx->kpub); | |
410c8acf | 1268 | return (-1); |
52c03a2a | 1269 | } |
00e64b67 | 1270 | kx->f = KXF_DEAD | KXF_PUBKEY; |
0617b6e7 | 1271 | start(kx, time(0)); |
1272 | resend(kx); | |
11c0039e | 1273 | /* Don't notify here: the ADD message hasn't gone out yet. */ |
410c8acf | 1274 | return (0); |
1275 | } | |
1276 | ||
1277 | /*----- That's all, folks -------------------------------------------------*/ |