Commit | Line | Data |
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410c8acf | 1 | /* -*-c-*- |
410c8acf | 2 | * |
3 | * Key exchange protocol | |
4 | * | |
5 | * (c) 2001 Straylight/Edgeware | |
6 | */ | |
7 | ||
e04c2d50 | 8 | /*----- Licensing notice --------------------------------------------------* |
410c8acf | 9 | * |
10 | * This file is part of Trivial IP Encryption (TrIPE). | |
11 | * | |
12 | * TrIPE is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
e04c2d50 | 16 | * |
410c8acf | 17 | * TrIPE is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
e04c2d50 | 21 | * |
410c8acf | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with TrIPE; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
410c8acf | 27 | /*----- Header files ------------------------------------------------------*/ |
28 | ||
29 | #include "tripe.h" | |
30 | ||
737cc271 | 31 | /*----- Brief protocol overview -------------------------------------------* |
32 | * | |
33 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let | |
34 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote | |
35 | * application of the symmetric packet protocol to a message; let | |
36 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% | |
37 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% | |
38 | * be Bob's public key. | |
39 | * | |
40 | * At the beginning of the session, Alice chooses | |
41 | * | |
42 | * %$\rho_A \inr \{0, \ldots q - 1\}$% | |
43 | * | |
44 | * We also have: | |
45 | * | |
46 | * %$r_A = g^{\rho_A}$% Alice's challenge | |
47 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie | |
9317aa92 | 48 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, a, r_A, r_B, b^{\rho_A})$% |
e04c2d50 | 49 | * Alice's challenge check value |
737cc271 | 50 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply |
51 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% | |
e04c2d50 | 52 | * Alice and Bob's shared secret key |
737cc271 | 53 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% |
e04c2d50 | 54 | * Alice's switch request value |
737cc271 | 55 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% |
e04c2d50 | 56 | * Alice's switch confirm value |
737cc271 | 57 | * |
58 | * The messages are then: | |
59 | * | |
60 | * %$\cookie{kx-pre-challenge}, r_A$% | |
61 | * Initial greeting. In state @KXS_CHAL@. | |
62 | * | |
737cc271 | 63 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
64 | * Here's a full challenge for you to answer. | |
65 | * | |
28461f0e | 66 | * %$\cookie{kx-reply}, r_A, c_B, v_A, E_K(r_B^\alpha))$% |
737cc271 | 67 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
68 | * to @KXS_COMMIT@. | |
69 | * | |
3cdc3f3a | 70 | * %$\cookie{kx-switch-rq}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
737cc271 | 71 | * Reply received: here's my reply. Committed; send data; move to |
72 | * @KXS_SWITCH@. | |
73 | * | |
74 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% | |
75 | * Switch received. Committed; send data; move to @KXS_SWITCH@. | |
e04c2d50 | 76 | */ |
737cc271 | 77 | |
3cdc3f3a | 78 | /*----- Static tables -----------------------------------------------------*/ |
79 | ||
80 | static const char *const pkname[] = { | |
c3c51798 | 81 | "pre-challenge", "challenge", "reply", "switch-rq", "switch-ok" |
3cdc3f3a | 82 | }; |
0617b6e7 | 83 | |
84 | /*----- Various utilities -------------------------------------------------*/ | |
410c8acf | 85 | |
e9fac70c MW |
86 | /* --- @VALIDP@ --- * |
87 | * | |
88 | * Arguments: @const keyexch *kx@ = key exchange state | |
89 | * @time_t now@ = current time in seconds | |
90 | * | |
91 | * Returns: Whether the challenge in the key-exchange state is still | |
92 | * valid or should be regenerated. | |
93 | */ | |
94 | ||
95 | #define VALIDP(kx, now) ((now) < (kx)->t_valid) | |
96 | ||
52c03a2a | 97 | /* --- @hashge@ --- * |
410c8acf | 98 | * |
b5c45da1 | 99 | * Arguments: @ghash *h@ = pointer to hash context |
52c03a2a | 100 | * @ge *x@ = pointer to group element |
410c8acf | 101 | * |
102 | * Returns: --- | |
103 | * | |
52c03a2a | 104 | * Use: Adds the hash of a group element to the context. Corrupts |
105 | * @buf_t@. | |
410c8acf | 106 | */ |
107 | ||
b5c45da1 | 108 | static void hashge(ghash *h, ge *x) |
410c8acf | 109 | { |
110 | buf b; | |
0617b6e7 | 111 | buf_init(&b, buf_t, sizeof(buf_t)); |
52c03a2a | 112 | G_TOBUF(gg, &b, x); |
410c8acf | 113 | assert(BOK(&b)); |
b5c45da1 | 114 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
410c8acf | 115 | } |
116 | ||
de7bd20b | 117 | /* --- @mpmask@ --- * |
5d418e24 | 118 | * |
de7bd20b MW |
119 | * Arguments: @buf *b@ = output buffer |
120 | * @mp *x@ = the plaintext integer | |
121 | * @size_t n@ = the expected size of the plaintext | |
5d418e24 | 122 | * @const octet *k@ = pointer to key material |
de7bd20b | 123 | * @size_t ksz@ = size of the key |
5d418e24 | 124 | * |
de7bd20b | 125 | * Returns: Pointer to the output. |
5d418e24 | 126 | * |
de7bd20b MW |
127 | * Use: Masks a multiprecision integer: returns %$x \xor H(k)$%, so |
128 | * it's a random oracle thing rather than an encryption thing. | |
5d418e24 | 129 | */ |
130 | ||
de7bd20b | 131 | static octet *mpmask(buf *b, mp *x, size_t n, const octet *k, size_t ksz) |
5d418e24 | 132 | { |
b5c45da1 | 133 | gcipher *mgf; |
de7bd20b | 134 | octet *p; |
5d418e24 | 135 | |
de7bd20b MW |
136 | if ((p = buf_get(b, n)) == 0) |
137 | return (0); | |
138 | mgf = GC_INIT(algs.mgf, k, ksz); | |
139 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
140 | trace(T_CRYPTO, "masking index = %s", mpstr(x)); | |
141 | trace_block(T_CRYPTO, "masking key", k, ksz); | |
142 | })) | |
143 | mp_storeb(x, buf_t, n); | |
144 | GC_ENCRYPT(mgf, buf_t, p, n); | |
145 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
146 | trace_block(T_CRYPTO, "index plaintext", buf_t, n); | |
147 | trace_block(T_CRYPTO, "masked ciphertext", p, n); | |
148 | })) | |
b5c45da1 | 149 | GC_DESTROY(mgf); |
de7bd20b | 150 | return (p); |
b5c45da1 | 151 | } |
152 | ||
de7bd20b MW |
153 | /* --- @mpunmask@ --- * |
154 | * | |
155 | * Arguments: @mp *d@ = the output integer | |
156 | * @const octet *p@ = pointer to the ciphertext | |
157 | * @size_t n@ = the size of the ciphertext | |
158 | * @const octet *k@ = pointer to key material | |
159 | * @size_t ksz@ = size of the key | |
160 | * | |
161 | * Returns: The decrypted integer, or null. | |
162 | * | |
163 | * Use: Unmasks a multiprecision integer. | |
164 | */ | |
165 | ||
166 | static mp *mpunmask(mp *d, const octet *p, size_t n, | |
167 | const octet *k, size_t ksz) | |
b5c45da1 | 168 | { |
169 | gcipher *mgf; | |
170 | ||
de7bd20b MW |
171 | mgf = GC_INIT(algs.mgf, k, ksz); |
172 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
173 | trace_block(T_CRYPTO, "unmasking key", k, ksz); | |
174 | trace_block(T_CRYPTO, "masked ciphertext", p, n); | |
175 | })) | |
176 | GC_DECRYPT(mgf, p, buf_t, n); | |
177 | d = mp_loadb(d, buf_t, n); | |
178 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
179 | trace_block(T_CRYPTO, "index plaintext", buf_t, n); | |
180 | trace(T_CRYPTO, "unmasked index = %s", mpstr(d)); | |
181 | })) | |
b5c45da1 | 182 | GC_DESTROY(mgf); |
de7bd20b MW |
183 | return (d); |
184 | } | |
185 | ||
186 | /* --- @hashcheck@ --- * | |
187 | * | |
188 | * Arguments: @ge *kpub@ = sender's public key | |
189 | * @ge *cc@ = receiver's challenge | |
190 | * @ge *c@ = sender's challenge | |
191 | * @ge *y@ = reply to sender's challenge | |
192 | * | |
193 | * Returns: Pointer to the hash value (in @buf_t@) | |
194 | * | |
195 | * Use: Computes the check-value hash, used to mask or unmask | |
196 | * indices to prove the validity of challenges. This computes | |
197 | * the masking key used in challenge check values. This is | |
198 | * really the heart of the whole thing, since it ensures that | |
199 | * the index can be recovered from the history of hashing | |
200 | * queries, which gives us (a) a proof that the authentication | |
201 | * process is zero-knowledge, and (b) a proof that the whole | |
202 | * key-exchange is deniable. | |
203 | */ | |
204 | ||
205 | static const octet *hashcheck(ge *kpub, ge *cc, ge *c, ge *y) | |
206 | { | |
207 | ghash *h = GH_INIT(algs.h); | |
208 | ||
209 | HASH_STRING(h, "tripe-expected-reply"); | |
210 | hashge(h, kpub); | |
211 | hashge(h, cc); | |
212 | hashge(h, c); | |
213 | hashge(h, y); | |
214 | GH_DONE(h, buf_t); | |
215 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
216 | trace(T_CRYPTO, "computing challenge check hash"); | |
217 | trace(T_CRYPTO, "public key = %s", gestr(gg, kpub)); | |
218 | trace(T_CRYPTO, "receiver challenge = %s", gestr(gg, cc)); | |
219 | trace(T_CRYPTO, "sender challenge = %s", gestr(gg, c)); | |
220 | trace(T_CRYPTO, "sender reply = %s", gestr(gg, y)); | |
221 | trace_block(T_CRYPTO, "hash output", buf_t, algs.hashsz); | |
222 | })) | |
223 | GH_DESTROY(h); | |
224 | return (buf_t); | |
225 | } | |
226 | ||
227 | /* --- @sendchallenge@ --- * | |
228 | * | |
229 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
230 | * @buf *b@ = output buffer for challenge | |
231 | * @ge *c@ = peer's actual challenge | |
232 | * @const octet *hc@ = peer's challenge cookie | |
233 | * | |
234 | * Returns: --- | |
235 | * | |
236 | * Use: Writes a full challenge to the message buffer. | |
237 | */ | |
238 | ||
239 | static void sendchallenge(keyexch *kx, buf *b, ge *c, const octet *hc) | |
240 | { | |
241 | G_TOBUF(gg, b, kx->c); | |
242 | buf_put(b, hc, algs.hashsz); | |
243 | mpmask(b, kx->alpha, indexsz, | |
244 | hashcheck(kpub, c, kx->c, kx->rx), algs.hashsz); | |
5d418e24 | 245 | } |
246 | ||
410c8acf | 247 | /* --- @timer@ --- * |
248 | * | |
249 | * Arguments: @struct timeval *tv@ = the current time | |
250 | * @void *v@ = pointer to key exchange context | |
251 | * | |
252 | * Returns: --- | |
253 | * | |
254 | * Use: Acts when the key exchange timer goes off. | |
255 | */ | |
256 | ||
257 | static void timer(struct timeval *tv, void *v) | |
258 | { | |
259 | keyexch *kx = v; | |
260 | kx->f &= ~KXF_TIMER; | |
261 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) | |
de014da6 | 262 | kx_start(kx, 0); |
410c8acf | 263 | } |
264 | ||
265 | /* --- @settimer@ --- * | |
266 | * | |
267 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
268 | * @time_t t@ = when to set the timer for | |
269 | * | |
270 | * Returns: --- | |
271 | * | |
272 | * Use: Sets the timer for the next key exchange attempt. | |
273 | */ | |
274 | ||
275 | static void settimer(keyexch *kx, time_t t) | |
276 | { | |
277 | struct timeval tv; | |
278 | if (kx->f & KXF_TIMER) | |
279 | sel_rmtimer(&kx->t); | |
280 | tv.tv_sec = t; | |
281 | tv.tv_usec = 0; | |
282 | sel_addtimer(&sel, &kx->t, &tv, timer, kx); | |
283 | kx->f |= KXF_TIMER; | |
284 | } | |
285 | ||
0617b6e7 | 286 | /*----- Challenge management ----------------------------------------------*/ |
287 | ||
288 | /* --- Notes on challenge management --- * | |
410c8acf | 289 | * |
0617b6e7 | 290 | * We may get multiple different replies to our key exchange; some will be |
291 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges | |
292 | * received will be added to the table and given a full response. After | |
293 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': | |
294 | * our existing challenge, followed by a hash of the sender's challenge. We | |
295 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All | |
296 | * properly-formed cookies are assigned a table slot: if none is spare, a | |
297 | * used slot is randomly selected and destroyed. A cookie always receives a | |
298 | * full reply. | |
299 | */ | |
300 | ||
301 | /* --- @kxc_destroy@ --- * | |
302 | * | |
303 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
410c8acf | 304 | * |
305 | * Returns: --- | |
306 | * | |
0617b6e7 | 307 | * Use: Disposes of a challenge block. |
410c8acf | 308 | */ |
309 | ||
0617b6e7 | 310 | static void kxc_destroy(kxchal *kxc) |
410c8acf | 311 | { |
0617b6e7 | 312 | if (kxc->f & KXF_TIMER) |
313 | sel_rmtimer(&kxc->t); | |
52c03a2a | 314 | G_DESTROY(gg, kxc->c); |
de7bd20b | 315 | G_DESTROY(gg, kxc->r); |
0617b6e7 | 316 | ks_drop(kxc->ks); |
317 | DESTROY(kxc); | |
318 | } | |
410c8acf | 319 | |
0617b6e7 | 320 | /* --- @kxc_stoptimer@ --- * |
321 | * | |
322 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
323 | * | |
324 | * Returns: --- | |
325 | * | |
326 | * Use: Stops the challenge's retry timer from sending messages. | |
327 | * Useful when the state machine is in the endgame of the | |
328 | * exchange. | |
329 | */ | |
410c8acf | 330 | |
0617b6e7 | 331 | static void kxc_stoptimer(kxchal *kxc) |
332 | { | |
333 | if (kxc->f & KXF_TIMER) | |
334 | sel_rmtimer(&kxc->t); | |
2de0ad0f | 335 | kxc->f &= ~KXF_TIMER; |
0617b6e7 | 336 | } |
410c8acf | 337 | |
0617b6e7 | 338 | /* --- @kxc_new@ --- * |
339 | * | |
340 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
0617b6e7 | 341 | * |
342 | * Returns: A pointer to the challenge block. | |
343 | * | |
344 | * Use: Returns a pointer to a new challenge block to fill in. | |
345 | */ | |
410c8acf | 346 | |
0617b6e7 | 347 | static kxchal *kxc_new(keyexch *kx) |
348 | { | |
349 | kxchal *kxc; | |
350 | unsigned i; | |
351 | ||
352 | /* --- If we're over reply threshold, discard one at random --- */ | |
353 | ||
354 | if (kx->nr < KX_NCHAL) | |
355 | i = kx->nr++; | |
356 | else { | |
357 | i = rand_global.ops->range(&rand_global, KX_NCHAL); | |
358 | kxc_destroy(kx->r[i]); | |
410c8acf | 359 | } |
360 | ||
0617b6e7 | 361 | /* --- Fill in the new structure --- */ |
410c8acf | 362 | |
0617b6e7 | 363 | kxc = CREATE(kxchal); |
52c03a2a | 364 | kxc->c = G_CREATE(gg); |
de7bd20b | 365 | kxc->r = G_CREATE(gg); |
0617b6e7 | 366 | kxc->ks = 0; |
367 | kxc->kx = kx; | |
368 | kxc->f = 0; | |
369 | kx->r[i] = kxc; | |
370 | return (kxc); | |
371 | } | |
410c8acf | 372 | |
0617b6e7 | 373 | /* --- @kxc_bychal@ --- * |
374 | * | |
375 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
52c03a2a | 376 | * @ge *c@ = challenge from remote host |
0617b6e7 | 377 | * |
378 | * Returns: Pointer to the challenge block, or null. | |
379 | * | |
380 | * Use: Finds a challenge block, given its challenge. | |
381 | */ | |
382 | ||
52c03a2a | 383 | static kxchal *kxc_bychal(keyexch *kx, ge *c) |
0617b6e7 | 384 | { |
385 | unsigned i; | |
386 | ||
387 | for (i = 0; i < kx->nr; i++) { | |
52c03a2a | 388 | if (G_EQ(gg, c, kx->r[i]->c)) |
0617b6e7 | 389 | return (kx->r[i]); |
390 | } | |
391 | return (0); | |
392 | } | |
393 | ||
394 | /* --- @kxc_byhc@ --- * | |
395 | * | |
396 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
397 | * @const octet *hc@ = challenge hash from remote host | |
398 | * | |
399 | * Returns: Pointer to the challenge block, or null. | |
400 | * | |
401 | * Use: Finds a challenge block, given a hash of its challenge. | |
402 | */ | |
410c8acf | 403 | |
0617b6e7 | 404 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
405 | { | |
406 | unsigned i; | |
407 | ||
408 | for (i = 0; i < kx->nr; i++) { | |
b5c45da1 | 409 | if (memcmp(hc, kx->r[i]->hc, algs.hashsz) == 0) |
0617b6e7 | 410 | return (kx->r[i]); |
410c8acf | 411 | } |
0617b6e7 | 412 | return (0); |
413 | } | |
414 | ||
415 | /* --- @kxc_answer@ --- * | |
416 | * | |
417 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
418 | * @kxchal *kxc@ = pointer to challenge block | |
419 | * | |
420 | * Returns: --- | |
421 | * | |
422 | * Use: Sends a reply to the remote host, according to the data in | |
423 | * this challenge block. | |
424 | */ | |
425 | ||
426 | static void kxc_answer(keyexch *kx, kxchal *kxc); | |
427 | ||
428 | static void kxc_timer(struct timeval *tv, void *v) | |
429 | { | |
430 | kxchal *kxc = v; | |
431 | kxc->f &= ~KXF_TIMER; | |
432 | kxc_answer(kxc->kx, kxc); | |
433 | } | |
434 | ||
435 | static void kxc_answer(keyexch *kx, kxchal *kxc) | |
436 | { | |
437 | stats *st = p_stats(kx->p); | |
de7bd20b | 438 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | KX_REPLY); |
0617b6e7 | 439 | struct timeval tv; |
440 | buf bb; | |
441 | ||
442 | /* --- Build the reply packet --- */ | |
443 | ||
de7bd20b MW |
444 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
445 | sendchallenge(kx, b, kxc->c, kxc->hc); | |
446 | buf_init(&bb, buf_i, sizeof(buf_i)); | |
447 | G_TORAW(gg, &bb, kxc->r); | |
448 | buf_flip(&bb); | |
449 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); | |
0617b6e7 | 450 | |
451 | /* --- Update the statistics --- */ | |
452 | ||
453 | if (BOK(b)) { | |
454 | st->n_kxout++; | |
455 | st->sz_kxout += BLEN(b); | |
456 | p_txend(kx->p); | |
457 | } | |
458 | ||
459 | /* --- Schedule another resend --- */ | |
460 | ||
461 | if (kxc->f & KXF_TIMER) | |
462 | sel_rmtimer(&kxc->t); | |
463 | gettimeofday(&tv, 0); | |
464 | tv.tv_sec += T_RETRY; | |
465 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); | |
466 | kxc->f |= KXF_TIMER; | |
467 | } | |
468 | ||
469 | /*----- Individual message handlers ---------------------------------------*/ | |
470 | ||
de7bd20b | 471 | /* --- @doprechallenge@ --- * |
0617b6e7 | 472 | * |
de7bd20b MW |
473 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
474 | * @buf *b@ = buffer containing the packet | |
0617b6e7 | 475 | * |
de7bd20b | 476 | * Returns: Zero if OK, nonzero of the packet was rejected. |
0617b6e7 | 477 | * |
de7bd20b | 478 | * Use: Processes a pre-challenge message. |
0617b6e7 | 479 | */ |
480 | ||
de7bd20b | 481 | static int doprechallenge(keyexch *kx, buf *b) |
0617b6e7 | 482 | { |
de7bd20b MW |
483 | stats *st = p_stats(kx->p); |
484 | ge *c = G_CREATE(gg); | |
b5c45da1 | 485 | ghash *h; |
0617b6e7 | 486 | |
de7bd20b MW |
487 | /* --- Ensure that we're in a sensible state --- */ |
488 | ||
489 | if (kx->s != KXS_CHAL) { | |
490 | a_warn("KX", "?PEER", kx->p, "unexpected", "pre-challenge", A_END); | |
491 | goto bad; | |
492 | } | |
493 | ||
494 | /* --- Unpack the packet --- */ | |
495 | ||
496 | if (G_FROMBUF(gg, b, c) || BLEFT(b)) | |
497 | goto bad; | |
b5c45da1 | 498 | |
0617b6e7 | 499 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
de7bd20b | 500 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); |
0617b6e7 | 501 | })) |
de7bd20b MW |
502 | |
503 | /* --- Send out a full challenge by return --- */ | |
504 | ||
505 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_CHAL); | |
506 | h = GH_INIT(algs.h); | |
507 | HASH_STRING(h, "tripe-cookie"); | |
508 | hashge(h, c); | |
509 | sendchallenge(kx, b, c, GH_DONE(h, 0)); | |
b5c45da1 | 510 | GH_DESTROY(h); |
de7bd20b MW |
511 | st->n_kxout++; |
512 | st->sz_kxout += BLEN(b); | |
513 | p_txend(kx->p); | |
514 | ||
515 | /* --- Done --- */ | |
516 | ||
517 | G_DESTROY(gg, c); | |
518 | return (0); | |
519 | ||
520 | bad: | |
521 | if (c) G_DESTROY(gg, c); | |
522 | return (-1); | |
0617b6e7 | 523 | } |
524 | ||
de7bd20b | 525 | /* --- @respond@ --- * |
0617b6e7 | 526 | * |
527 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
de7bd20b | 528 | * @unsigned msg@ = message code for this packet |
0617b6e7 | 529 | * @buf *b@ = buffer containing the packet |
530 | * | |
de7bd20b | 531 | * Returns: Key-exchange challenge block, or null. |
0617b6e7 | 532 | * |
de7bd20b MW |
533 | * Use: Computes a response for the given challenge, entering it into |
534 | * a challenge block and so on. | |
0617b6e7 | 535 | */ |
536 | ||
de7bd20b | 537 | static kxchal *respond(keyexch *kx, unsigned msg, buf *b) |
0617b6e7 | 538 | { |
52c03a2a | 539 | ge *c = G_CREATE(gg); |
de7bd20b MW |
540 | ge *r = G_CREATE(gg); |
541 | ge *cc = G_CREATE(gg); | |
542 | const octet *hc, *ck; | |
543 | size_t x, y, z; | |
544 | mp *cv = 0; | |
0617b6e7 | 545 | kxchal *kxc; |
de7bd20b MW |
546 | ghash *h = 0; |
547 | buf bb; | |
548 | int ok; | |
0617b6e7 | 549 | |
550 | /* --- Unpack the packet --- */ | |
551 | ||
52c03a2a | 552 | if (G_FROMBUF(gg, b, c) || |
de7bd20b MW |
553 | (hc = buf_get(b, algs.hashsz)) == 0 || |
554 | (ck = buf_get(b, indexsz)) == 0) { | |
f43df819 | 555 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 556 | goto bad; |
557 | } | |
0617b6e7 | 558 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a | 559 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); |
de7bd20b MW |
560 | trace_block(T_CRYPTO, "crypto: cookie", hc, algs.hashsz); |
561 | trace_block(T_CRYPTO, "crypto: check-value", ck, indexsz); | |
0617b6e7 | 562 | })) |
563 | ||
0617b6e7 | 564 | /* --- Discard a packet with an invalid cookie --- */ |
565 | ||
b5c45da1 | 566 | if (hc && memcmp(hc, kx->hc, algs.hashsz) != 0) { |
5ac9463b | 567 | a_warn("KX", "?PEER", kx->p, "incorrect", "cookie", A_END); |
0617b6e7 | 568 | goto bad; |
569 | } | |
570 | ||
de7bd20b MW |
571 | /* --- Recover the check value and verify it --- * |
572 | * | |
573 | * To avoid recomputation on replays, we store a hash of the `right' | |
574 | * value. The `correct' value is unique, so this is right. | |
410c8acf | 575 | * |
de7bd20b | 576 | * This will also find a challenge block and, if necessary, populate it. |
410c8acf | 577 | */ |
578 | ||
de7bd20b MW |
579 | if ((kxc = kxc_bychal(kx, c)) != 0) { |
580 | h = GH_INIT(algs.h); | |
581 | HASH_STRING(h, "tripe-check-hash"); | |
582 | GH_HASH(h, ck, indexsz); | |
583 | ok = !memcmp(kxc->ck, GH_DONE(h, 0), algs.hashsz); | |
584 | GH_DESTROY(h); | |
585 | if (!ok) goto badcheck; | |
586 | } else { | |
587 | ||
588 | /* --- Compute the reply, and check the magic --- */ | |
589 | ||
590 | G_EXP(gg, r, c, kpriv); | |
591 | cv = mpunmask(MP_NEW, ck, indexsz, | |
592 | hashcheck(kx->kpub, kx->c, c, r), algs.hashsz); | |
593 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
594 | trace(T_CRYPTO, "crypto: computed reply = %s", gestr(gg, r)); | |
595 | trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(cv)); | |
596 | })) | |
597 | if (MP_CMP(cv, >, gg->r) || | |
598 | (G_EXP(gg, cc, gg->g, cv), !G_EQ(gg, c, cc))) | |
599 | goto badcheck; | |
600 | ||
601 | /* --- Fill in a new challenge block --- */ | |
e04c2d50 | 602 | |
de7bd20b | 603 | kxc = kxc_new(kx); |
52c03a2a | 604 | G_COPY(gg, kxc->c, c); |
de7bd20b | 605 | G_COPY(gg, kxc->r, r); |
0617b6e7 | 606 | |
de7bd20b MW |
607 | h = GH_INIT(algs.h); |
608 | HASH_STRING(h, "tripe-check-hash"); | |
609 | GH_HASH(h, ck, indexsz); | |
5fb10b44 | 610 | GH_DONE(h, kxc->ck); |
de7bd20b | 611 | GH_DESTROY(h); |
0617b6e7 | 612 | |
b5c45da1 | 613 | h = GH_INIT(algs.h); |
614 | HASH_STRING(h, "tripe-cookie"); | |
615 | hashge(h, kxc->c); | |
616 | GH_DONE(h, kxc->hc); | |
617 | GH_DESTROY(h); | |
618 | ||
619 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
620 | trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, algs.hashsz); | |
621 | })) | |
0617b6e7 | 622 | |
0617b6e7 | 623 | /* --- Work out the shared key --- */ |
624 | ||
52c03a2a | 625 | G_EXP(gg, r, c, kx->alpha); |
b5c45da1 | 626 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
627 | trace(T_CRYPTO, "crypto: shared secret = %s", gestr(gg, r)); | |
628 | })) | |
0617b6e7 | 629 | |
630 | /* --- Compute the switch messages --- */ | |
631 | ||
b5c45da1 | 632 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); |
633 | hashge(h, kx->c); hashge(h, kxc->c); | |
634 | GH_DONE(h, kxc->hswrq_out); GH_DESTROY(h); | |
635 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); | |
636 | hashge(h, kx->c); hashge(h, kxc->c); | |
637 | GH_DONE(h, kxc->hswok_out); GH_DESTROY(h); | |
0617b6e7 | 638 | |
b5c45da1 | 639 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); |
640 | hashge(h, kxc->c); hashge(h, kx->c); | |
641 | GH_DONE(h, kxc->hswrq_in); GH_DESTROY(h); | |
642 | h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); | |
643 | hashge(h, kxc->c); hashge(h, kx->c); | |
644 | GH_DONE(h, kxc->hswok_in); GH_DESTROY(h); | |
0617b6e7 | 645 | |
646 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
0617b6e7 | 647 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
b5c45da1 | 648 | kxc->hswrq_out, algs.hashsz); |
0617b6e7 | 649 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
b5c45da1 | 650 | kxc->hswok_out, algs.hashsz); |
0617b6e7 | 651 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
b5c45da1 | 652 | kxc->hswrq_in, algs.hashsz); |
0617b6e7 | 653 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
b5c45da1 | 654 | kxc->hswok_in, algs.hashsz); |
0617b6e7 | 655 | })) |
656 | ||
657 | /* --- Create a new symmetric keyset --- */ | |
658 | ||
de7bd20b MW |
659 | buf_init(&bb, buf_o, sizeof(buf_o)); |
660 | G_TOBUF(gg, &bb, kx->c); x = BLEN(&bb); | |
661 | G_TOBUF(gg, &bb, kxc->c); y = BLEN(&bb); | |
662 | G_TOBUF(gg, &bb, r); z = BLEN(&bb); | |
663 | assert(BOK(&bb)); | |
0617b6e7 | 664 | |
de7bd20b | 665 | kxc->ks = ks_gen(BBASE(&bb), x, y, z, kx->p); |
410c8acf | 666 | } |
667 | ||
de7bd20b MW |
668 | G_DESTROY(gg, c); |
669 | G_DESTROY(gg, cc); | |
670 | G_DESTROY(gg, r); | |
671 | mp_drop(cv); | |
672 | return (kxc); | |
410c8acf | 673 | |
de7bd20b MW |
674 | badcheck: |
675 | a_warn("KX", "?PEER", kx->p, "bad-expected-reply-log", A_END); | |
676 | goto bad; | |
677 | bad: | |
678 | G_DESTROY(gg, c); | |
679 | G_DESTROY(gg, cc); | |
680 | G_DESTROY(gg, r); | |
681 | mp_drop(cv); | |
e04c2d50 | 682 | return (0); |
de7bd20b | 683 | } |
0617b6e7 | 684 | |
de7bd20b MW |
685 | /* --- @dochallenge@ --- * |
686 | * | |
687 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
688 | * @unsigned msg@ = message code for the packet | |
689 | * @buf *b@ = buffer containing the packet | |
690 | * | |
691 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
692 | * | |
693 | * Use: Processes a packet containing a challenge. | |
694 | */ | |
0617b6e7 | 695 | |
de7bd20b MW |
696 | static int dochallenge(keyexch *kx, buf *b) |
697 | { | |
698 | kxchal *kxc; | |
0617b6e7 | 699 | |
de7bd20b MW |
700 | if (kx->s != KXS_CHAL) { |
701 | a_warn("KX", "?PEER", kx->p, "unexpected", "challenge", A_END); | |
702 | goto bad; | |
703 | } | |
704 | if ((kxc = respond(kx, KX_CHAL, b)) == 0) | |
705 | goto bad; | |
706 | if (BLEFT(b)) { | |
707 | a_warn("KX", "?PEER", kx->p, "invalid", "challenge", A_END); | |
708 | goto bad; | |
709 | } | |
710 | kxc_answer(kx, kxc); | |
0617b6e7 | 711 | return (0); |
712 | ||
713 | bad: | |
0617b6e7 | 714 | return (-1); |
410c8acf | 715 | } |
716 | ||
0617b6e7 | 717 | /* --- @resend@ --- * |
410c8acf | 718 | * |
719 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
410c8acf | 720 | * |
721 | * Returns: --- | |
722 | * | |
0617b6e7 | 723 | * Use: Sends the next message for a key exchange. |
410c8acf | 724 | */ |
725 | ||
0617b6e7 | 726 | static void resend(keyexch *kx) |
410c8acf | 727 | { |
0617b6e7 | 728 | kxchal *kxc; |
729 | buf bb; | |
730 | stats *st = p_stats(kx->p); | |
410c8acf | 731 | buf *b; |
732 | ||
0617b6e7 | 733 | switch (kx->s) { |
734 | case KXS_CHAL: | |
00e64b67 | 735 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
736 | p_name(kx->p)); ) | |
0617b6e7 | 737 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
52c03a2a | 738 | G_TOBUF(gg, b, kx->c); |
0617b6e7 | 739 | break; |
740 | case KXS_COMMIT: | |
00e64b67 | 741 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
742 | p_name(kx->p)); ) | |
0617b6e7 | 743 | kxc = kx->r[0]; |
744 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); | |
b5c45da1 | 745 | buf_put(b, kx->hc, algs.hashsz); |
746 | buf_put(b, kxc->hc, algs.hashsz); | |
0617b6e7 | 747 | buf_init(&bb, buf_i, sizeof(buf_i)); |
de7bd20b | 748 | G_TORAW(gg, &bb, kxc->r); |
b5c45da1 | 749 | buf_put(&bb, kxc->hswrq_out, algs.hashsz); |
0617b6e7 | 750 | buf_flip(&bb); |
7ed14135 | 751 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 | 752 | break; |
753 | case KXS_SWITCH: | |
00e64b67 | 754 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 | 755 | p_name(kx->p)); ) |
756 | kxc = kx->r[0]; | |
757 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); | |
758 | buf_init(&bb, buf_i, sizeof(buf_i)); | |
b5c45da1 | 759 | buf_put(&bb, kxc->hswok_out, algs.hashsz); |
0617b6e7 | 760 | buf_flip(&bb); |
7ed14135 | 761 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 | 762 | break; |
763 | default: | |
764 | abort(); | |
410c8acf | 765 | } |
0617b6e7 | 766 | |
767 | if (BOK(b)) { | |
768 | st->n_kxout++; | |
769 | st->sz_kxout += BLEN(b); | |
770 | p_txend(kx->p); | |
771 | } | |
772 | ||
773 | if (kx->s < KXS_SWITCH) | |
774 | settimer(kx, time(0) + T_RETRY); | |
410c8acf | 775 | } |
776 | ||
de7bd20b | 777 | /* --- @decryptrest@ --- * |
0617b6e7 | 778 | * |
779 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de7bd20b MW |
780 | * @kxchal *kxc@ = pointer to challenge block |
781 | * @unsigned msg@ = type of incoming message | |
0617b6e7 | 782 | * @buf *b@ = encrypted remainder of the packet |
783 | * | |
de7bd20b | 784 | * Returns: Zero if OK, nonzero on some kind of error. |
0617b6e7 | 785 | * |
de7bd20b MW |
786 | * Use: Decrypts the remainder of the packet, and points @b@ at the |
787 | * recovered plaintext. | |
0617b6e7 | 788 | */ |
789 | ||
de7bd20b | 790 | static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b) |
410c8acf | 791 | { |
0617b6e7 | 792 | buf bb; |
0617b6e7 | 793 | |
de7bd20b MW |
794 | buf_init(&bb, buf_o, sizeof(buf_o)); |
795 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | msg, b, &bb)) { | |
796 | a_warn("KX", "?PEER", kx->p, "decrypt-failed", "%s", pkname[msg], A_END); | |
797 | return (-1); | |
0617b6e7 | 798 | } |
12a26b8b | 799 | if (!BOK(&bb)) return (-1); |
de7bd20b MW |
800 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
801 | return (0); | |
802 | } | |
410c8acf | 803 | |
de7bd20b MW |
804 | /* --- @checkresponse@ --- * |
805 | * | |
806 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
807 | * @unsigned msg@ = type of incoming message | |
808 | * @buf *b@ = decrypted remainder of the packet | |
809 | * | |
810 | * Returns: Zero if OK, nonzero on some kind of error. | |
811 | * | |
812 | * Use: Checks a reply or switch packet, ensuring that its response | |
813 | * is correct. | |
814 | */ | |
0617b6e7 | 815 | |
de7bd20b MW |
816 | static int checkresponse(keyexch *kx, unsigned msg, buf *b) |
817 | { | |
818 | ge *r = G_CREATE(gg); | |
0617b6e7 | 819 | |
5251b2e9 | 820 | if (G_FROMRAW(gg, b, r)) { |
de7bd20b | 821 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 822 | goto bad; |
823 | } | |
824 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
52c03a2a | 825 | trace(T_CRYPTO, "crypto: reply = %s", gestr(gg, r)); |
0617b6e7 | 826 | })) |
52c03a2a | 827 | if (!G_EQ(gg, r, kx->rx)) { |
de7bd20b | 828 | a_warn("KX", "?PEER", kx->p, "incorrect", "response", A_END); |
0617b6e7 | 829 | goto bad; |
830 | } | |
831 | ||
52c03a2a | 832 | G_DESTROY(gg, r); |
de7bd20b | 833 | return (0); |
0617b6e7 | 834 | |
835 | bad: | |
de7bd20b MW |
836 | G_DESTROY(gg, r); |
837 | return (-1); | |
410c8acf | 838 | } |
839 | ||
0617b6e7 | 840 | /* --- @commit@ --- * |
410c8acf | 841 | * |
842 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 843 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf | 844 | * |
845 | * Returns: --- | |
846 | * | |
0617b6e7 | 847 | * Use: Commits to a particular challenge as being the `right' one, |
848 | * since a reply has arrived for it. | |
410c8acf | 849 | */ |
850 | ||
0617b6e7 | 851 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf | 852 | { |
0617b6e7 | 853 | unsigned i; |
410c8acf | 854 | |
0617b6e7 | 855 | for (i = 0; i < kx->nr; i++) { |
856 | if (kx->r[i] != kxc) | |
857 | kxc_destroy(kx->r[i]); | |
858 | } | |
859 | kx->r[0] = kxc; | |
860 | kx->nr = 1; | |
861 | kxc_stoptimer(kxc); | |
e04c2d50 | 862 | ksl_link(kx->ks, kxc->ks); |
410c8acf | 863 | } |
864 | ||
0617b6e7 | 865 | /* --- @doreply@ --- * |
410c8acf | 866 | * |
867 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 868 | * @buf *b@ = buffer containing packet |
410c8acf | 869 | * |
0617b6e7 | 870 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 871 | * |
0617b6e7 | 872 | * Use: Handles a reply packet. This doesn't handle the various |
873 | * switch packets: they're rather too different. | |
410c8acf | 874 | */ |
875 | ||
0617b6e7 | 876 | static int doreply(keyexch *kx, buf *b) |
410c8acf | 877 | { |
0617b6e7 | 878 | kxchal *kxc; |
879 | ||
880 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { | |
f43df819 | 881 | a_warn("KX", "?PEER", kx->p, "unexpected", "reply", A_END); |
0617b6e7 | 882 | goto bad; |
883 | } | |
de7bd20b MW |
884 | if ((kxc = respond(kx, KX_REPLY, b)) == 0 || |
885 | decryptrest(kx, kxc, KX_REPLY, b) || | |
886 | checkresponse(kx, KX_REPLY, b)) | |
0617b6e7 | 887 | goto bad; |
888 | if (BLEFT(b)) { | |
f43df819 | 889 | a_warn("KX", "?PEER", kx->p, "invalid", "reply", A_END); |
0617b6e7 | 890 | goto bad; |
e04c2d50 | 891 | } |
0617b6e7 | 892 | if (kx->s == KXS_CHAL) { |
893 | commit(kx, kxc); | |
894 | kx->s = KXS_COMMIT; | |
895 | } | |
896 | resend(kx); | |
897 | return (0); | |
898 | ||
899 | bad: | |
900 | return (-1); | |
410c8acf | 901 | } |
902 | ||
3cdc3f3a | 903 | /* --- @kxfinish@ --- * |
904 | * | |
905 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
906 | * | |
907 | * Returns: --- | |
908 | * | |
909 | * Use: Sets everything up following a successful key exchange. | |
910 | */ | |
911 | ||
912 | static void kxfinish(keyexch *kx) | |
913 | { | |
914 | kxchal *kxc = kx->r[0]; | |
915 | ks_activate(kxc->ks); | |
62b5e3ec | 916 | settimer(kx, time(0) + T_REGEN); |
3cdc3f3a | 917 | kx->s = KXS_SWITCH; |
f43df819 | 918 | a_notify("KXDONE", "?PEER", kx->p, A_END); |
3cdc3f3a | 919 | p_stats(kx->p)->t_kx = time(0); |
920 | } | |
921 | ||
0617b6e7 | 922 | /* --- @doswitch@ --- * |
410c8acf | 923 | * |
0617b6e7 | 924 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
925 | * @buf *b@ = pointer to buffer containing packet | |
410c8acf | 926 | * |
0617b6e7 | 927 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 928 | * |
0617b6e7 | 929 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf | 930 | */ |
931 | ||
0617b6e7 | 932 | static int doswitch(keyexch *kx, buf *b) |
410c8acf | 933 | { |
0617b6e7 | 934 | const octet *hc_in, *hc_out, *hswrq; |
935 | kxchal *kxc; | |
410c8acf | 936 | |
b5c45da1 | 937 | if ((hc_in = buf_get(b, algs.hashsz)) == 0 || |
938 | (hc_out = buf_get(b, algs.hashsz)) == 0) { | |
f43df819 | 939 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); |
0617b6e7 | 940 | goto bad; |
410c8acf | 941 | } |
de7bd20b MW |
942 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
943 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, algs.hashsz); | |
944 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, algs.hashsz); | |
945 | })) | |
946 | if ((kxc = kxc_byhc(kx, hc_in)) == 0 || | |
947 | memcmp(hc_out, kx->hc, algs.hashsz) != 0) { | |
948 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); | |
949 | goto bad; | |
950 | } | |
951 | if (decryptrest(kx, kxc, KX_SWITCH, b) || | |
952 | checkresponse(kx, KX_SWITCH, b)) | |
0617b6e7 | 953 | goto bad; |
b5c45da1 | 954 | if ((hswrq = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { |
5ac9463b | 955 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); |
0617b6e7 | 956 | goto bad; |
957 | } | |
958 | IF_TRACING(T_KEYEXCH, { | |
b5c45da1 | 959 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, algs.hashsz); |
0617b6e7 | 960 | }) |
b5c45da1 | 961 | if (memcmp(hswrq, kxc->hswrq_in, algs.hashsz) != 0) { |
f43df819 | 962 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); |
0617b6e7 | 963 | goto bad; |
964 | } | |
de7bd20b MW |
965 | if (kx->s == KXS_CHAL) |
966 | commit(kx, kxc); | |
967 | if (kx->s < KXS_SWITCH) | |
968 | kxfinish(kx); | |
0617b6e7 | 969 | resend(kx); |
970 | return (0); | |
971 | ||
972 | bad: | |
973 | return (-1); | |
410c8acf | 974 | } |
975 | ||
0617b6e7 | 976 | /* --- @doswitchok@ --- * |
977 | * | |
978 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
979 | * @buf *b@ = pointer to buffer containing packet | |
980 | * | |
981 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
982 | * | |
983 | * Use: Handles a reply with a switch request bolted onto it. | |
984 | */ | |
985 | ||
986 | static int doswitchok(keyexch *kx, buf *b) | |
410c8acf | 987 | { |
0617b6e7 | 988 | const octet *hswok; |
989 | kxchal *kxc; | |
990 | buf bb; | |
410c8acf | 991 | |
0617b6e7 | 992 | if (kx->s < KXS_COMMIT) { |
f43df819 | 993 | a_warn("KX", "?PEER", kx->p, "unexpected", "switch-ok", A_END); |
0617b6e7 | 994 | goto bad; |
410c8acf | 995 | } |
0617b6e7 | 996 | kxc = kx->r[0]; |
997 | buf_init(&bb, buf_o, sizeof(buf_o)); | |
de7bd20b | 998 | if (decryptrest(kx, kxc, KX_SWITCHOK, b)) |
0617b6e7 | 999 | goto bad; |
b5c45da1 | 1000 | if ((hswok = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { |
5ac9463b | 1001 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-ok", A_END); |
0617b6e7 | 1002 | goto bad; |
1003 | } | |
1004 | IF_TRACING(T_KEYEXCH, { | |
b5c45da1 | 1005 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", |
1006 | hswok, algs.hashsz); | |
0617b6e7 | 1007 | }) |
b5c45da1 | 1008 | if (memcmp(hswok, kxc->hswok_in, algs.hashsz) != 0) { |
f43df819 | 1009 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-ok", A_END); |
0617b6e7 | 1010 | goto bad; |
1011 | } | |
3cdc3f3a | 1012 | if (kx->s < KXS_SWITCH) |
1013 | kxfinish(kx); | |
0617b6e7 | 1014 | return (0); |
1015 | ||
1016 | bad: | |
e04c2d50 | 1017 | return (-1); |
0617b6e7 | 1018 | } |
1019 | ||
1020 | /*----- Main code ---------------------------------------------------------*/ | |
1021 | ||
1022 | /* --- @stop@ --- * | |
1023 | * | |
1024 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1025 | * | |
1026 | * Returns: --- | |
1027 | * | |
1028 | * Use: Stops a key exchange dead in its tracks. Throws away all of | |
1029 | * the context information. The context is left in an | |
1030 | * inconsistent state. The only functions which understand this | |
1031 | * state are @kx_free@ and @kx_init@ (which cause it internally | |
1032 | * it), and @start@ (which expects it to be the prevailing | |
1033 | * state). | |
1034 | */ | |
1035 | ||
1036 | static void stop(keyexch *kx) | |
1037 | { | |
1038 | unsigned i; | |
1039 | ||
00e64b67 | 1040 | if (kx->f & KXF_DEAD) |
1041 | return; | |
1042 | ||
0617b6e7 | 1043 | if (kx->f & KXF_TIMER) |
1044 | sel_rmtimer(&kx->t); | |
1045 | for (i = 0; i < kx->nr; i++) | |
1046 | kxc_destroy(kx->r[i]); | |
1047 | mp_drop(kx->alpha); | |
52c03a2a | 1048 | G_DESTROY(gg, kx->c); |
1049 | G_DESTROY(gg, kx->rx); | |
00e64b67 | 1050 | kx->t_valid = 0; |
1051 | kx->f |= KXF_DEAD; | |
1052 | kx->f &= ~KXF_TIMER; | |
0617b6e7 | 1053 | } |
1054 | ||
1055 | /* --- @start@ --- * | |
1056 | * | |
1057 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1058 | * @time_t now@ = the current time | |
1059 | * | |
1060 | * Returns: --- | |
1061 | * | |
1062 | * Use: Starts a new key exchange with the peer. The context must be | |
1063 | * in the bizarre state left by @stop@ or @kx_init@. | |
1064 | */ | |
1065 | ||
1066 | static void start(keyexch *kx, time_t now) | |
1067 | { | |
b5c45da1 | 1068 | ghash *h; |
0617b6e7 | 1069 | |
00e64b67 | 1070 | assert(kx->f & KXF_DEAD); |
1071 | ||
010e6f63 | 1072 | kx->f &= ~(KXF_DEAD | KXF_CORK); |
0617b6e7 | 1073 | kx->nr = 0; |
52c03a2a | 1074 | kx->alpha = mprand_range(MP_NEW, gg->r, &rand_global, 0); |
1075 | kx->c = G_CREATE(gg); G_EXP(gg, kx->c, gg->g, kx->alpha); | |
1076 | kx->rx = G_CREATE(gg); G_EXP(gg, kx->rx, kx->kpub, kx->alpha); | |
0617b6e7 | 1077 | kx->s = KXS_CHAL; |
1078 | kx->t_valid = now + T_VALID; | |
1079 | ||
b5c45da1 | 1080 | h = GH_INIT(algs.h); |
1081 | HASH_STRING(h, "tripe-cookie"); | |
1082 | hashge(h, kx->c); | |
1083 | GH_DONE(h, kx->hc); | |
1084 | GH_DESTROY(h); | |
0617b6e7 | 1085 | |
1086 | IF_TRACING(T_KEYEXCH, { | |
1087 | trace(T_KEYEXCH, "keyexch: creating new challenge"); | |
1088 | IF_TRACING(T_CRYPTO, { | |
1089 | trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); | |
52c03a2a | 1090 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, kx->c)); |
1091 | trace(T_CRYPTO, "crypto: expected response = %s", gestr(gg, kx->rx)); | |
b5c45da1 | 1092 | trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, algs.hashsz); |
0617b6e7 | 1093 | }) |
1094 | }) | |
410c8acf | 1095 | } |
1096 | ||
00e64b67 | 1097 | /* --- @checkpub@ --- * |
1098 | * | |
1099 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1100 | * | |
1101 | * Returns: Zero if OK, nonzero if the peer's public key has expired. | |
1102 | * | |
1103 | * Use: Deactivates the key-exchange until the peer acquires a new | |
1104 | * public key. | |
1105 | */ | |
1106 | ||
1107 | static int checkpub(keyexch *kx) | |
1108 | { | |
1109 | time_t now; | |
1110 | if (kx->f & KXF_DEAD) | |
1111 | return (-1); | |
1112 | now = time(0); | |
1113 | if (KEY_EXPIRED(now, kx->texp_kpub)) { | |
1114 | stop(kx); | |
f43df819 | 1115 | a_warn("KX", "?PEER", kx->p, "public-key-expired", A_END); |
52c03a2a | 1116 | G_COPY(gg, kx->kpub, gg->i); |
00e64b67 | 1117 | kx->f &= ~KXF_PUBKEY; |
1118 | return (-1); | |
1119 | } | |
1120 | return (0); | |
1121 | } | |
1122 | ||
0617b6e7 | 1123 | /* --- @kx_start@ --- * |
410c8acf | 1124 | * |
1125 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de014da6 | 1126 | * @int forcep@ = nonzero to ignore the quiet timer |
410c8acf | 1127 | * |
1128 | * Returns: --- | |
1129 | * | |
0617b6e7 | 1130 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1131 | * a new challenge is sent (unless the quiet timer forbids | |
1132 | * this); if no exchange is in progress, one is commenced. | |
410c8acf | 1133 | */ |
1134 | ||
de014da6 | 1135 | void kx_start(keyexch *kx, int forcep) |
410c8acf | 1136 | { |
1137 | time_t now = time(0); | |
410c8acf | 1138 | |
00e64b67 | 1139 | if (checkpub(kx)) |
1140 | return; | |
de014da6 | 1141 | if (forcep || !VALIDP(kx, now)) { |
0617b6e7 | 1142 | stop(kx); |
1143 | start(kx, now); | |
f43df819 | 1144 | a_notify("KXSTART", "?PEER", kx->p, A_END); |
410c8acf | 1145 | } |
0617b6e7 | 1146 | resend(kx); |
1147 | } | |
1148 | ||
1149 | /* --- @kx_message@ --- * | |
1150 | * | |
1151 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1152 | * @unsigned msg@ = the message code | |
1153 | * @buf *b@ = pointer to buffer containing the packet | |
1154 | * | |
1155 | * Returns: --- | |
1156 | * | |
1157 | * Use: Reads a packet containing key exchange messages and handles | |
1158 | * it. | |
1159 | */ | |
1160 | ||
1161 | void kx_message(keyexch *kx, unsigned msg, buf *b) | |
1162 | { | |
1163 | time_t now = time(0); | |
1164 | stats *st = p_stats(kx->p); | |
1165 | size_t sz = BSZ(b); | |
1166 | int rc; | |
1167 | ||
010e6f63 MW |
1168 | if (kx->f & KXF_CORK) { |
1169 | start(kx, now); | |
1170 | settimer(kx, now + T_RETRY); | |
1171 | a_notify("KXSTART", A_END); | |
1172 | } | |
1173 | ||
00e64b67 | 1174 | if (checkpub(kx)) |
1175 | return; | |
1176 | ||
3cdc3f3a | 1177 | if (!VALIDP(kx, now)) { |
0617b6e7 | 1178 | stop(kx); |
1179 | start(kx, now); | |
410c8acf | 1180 | } |
0617b6e7 | 1181 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", |
1182 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) | |
1183 | ||
1184 | switch (msg) { | |
1185 | case KX_PRECHAL: | |
de7bd20b MW |
1186 | rc = doprechallenge(kx, b); |
1187 | break; | |
0617b6e7 | 1188 | case KX_CHAL: |
de7bd20b | 1189 | rc = dochallenge(kx, b); |
0617b6e7 | 1190 | break; |
1191 | case KX_REPLY: | |
1192 | rc = doreply(kx, b); | |
1193 | break; | |
1194 | case KX_SWITCH: | |
1195 | rc = doswitch(kx, b); | |
1196 | break; | |
1197 | case KX_SWITCHOK: | |
1198 | rc = doswitchok(kx, b); | |
1199 | break; | |
1200 | default: | |
f43df819 | 1201 | a_warn("KX", "?PEER", kx->p, "unknown-message", "0x%02x", msg, A_END); |
0617b6e7 | 1202 | rc = -1; |
1203 | break; | |
410c8acf | 1204 | } |
410c8acf | 1205 | |
0617b6e7 | 1206 | if (rc) |
1207 | st->n_reject++; | |
1208 | else { | |
1209 | st->n_kxin++; | |
1210 | st->sz_kxin += sz; | |
1211 | } | |
410c8acf | 1212 | } |
1213 | ||
1214 | /* --- @kx_free@ --- * | |
1215 | * | |
1216 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1217 | * | |
1218 | * Returns: --- | |
1219 | * | |
1220 | * Use: Frees everything in a key exchange context. | |
1221 | */ | |
1222 | ||
1223 | void kx_free(keyexch *kx) | |
1224 | { | |
0617b6e7 | 1225 | stop(kx); |
52c03a2a | 1226 | G_DESTROY(gg, kx->kpub); |
410c8acf | 1227 | } |
1228 | ||
1229 | /* --- @kx_newkeys@ --- * | |
1230 | * | |
1231 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1232 | * | |
1233 | * Returns: --- | |
1234 | * | |
1235 | * Use: Informs the key exchange module that its keys may have | |
1236 | * changed. If fetching the new keys fails, the peer will be | |
1237 | * destroyed, we log messages and struggle along with the old | |
1238 | * keys. | |
1239 | */ | |
1240 | ||
1241 | void kx_newkeys(keyexch *kx) | |
1242 | { | |
48b84569 | 1243 | if (km_getpubkey(p_tag(kx->p), kx->kpub, &kx->texp_kpub)) |
410c8acf | 1244 | return; |
00e64b67 | 1245 | kx->f |= KXF_PUBKEY; |
1246 | if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { | |
410c8acf | 1247 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1248 | p_name(kx->p)); ) | |
00e64b67 | 1249 | stop(kx); |
1250 | start(kx, time(0)); | |
1251 | resend(kx); | |
410c8acf | 1252 | } |
1253 | } | |
1254 | ||
1255 | /* --- @kx_init@ --- * | |
1256 | * | |
1257 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1258 | * @peer *p@ = pointer to peer context | |
1259 | * @keyset **ks@ = pointer to keyset list | |
010e6f63 | 1260 | * @unsigned f@ = various useful flags |
410c8acf | 1261 | * |
1262 | * Returns: Zero if OK, nonzero if it failed. | |
1263 | * | |
1264 | * Use: Initializes a key exchange module. The module currently | |
1265 | * contains no keys, and will attempt to initiate a key | |
1266 | * exchange. | |
1267 | */ | |
1268 | ||
010e6f63 | 1269 | int kx_init(keyexch *kx, peer *p, keyset **ks, unsigned f) |
410c8acf | 1270 | { |
1271 | kx->ks = ks; | |
1272 | kx->p = p; | |
52c03a2a | 1273 | kx->kpub = G_CREATE(gg); |
48b84569 | 1274 | if (km_getpubkey(p_tag(p), kx->kpub, &kx->texp_kpub)) { |
52c03a2a | 1275 | G_DESTROY(gg, kx->kpub); |
410c8acf | 1276 | return (-1); |
52c03a2a | 1277 | } |
010e6f63 MW |
1278 | kx->f = KXF_DEAD | KXF_PUBKEY | f; |
1279 | if (!(kx->f & KXF_CORK)) { | |
1280 | start(kx, time(0)); | |
1281 | resend(kx); | |
1282 | /* Don't notify here: the ADD message hasn't gone out yet. */ | |
1283 | } | |
410c8acf | 1284 | return (0); |
1285 | } | |
1286 | ||
1287 | /*----- That's all, folks -------------------------------------------------*/ |