3 * Key exchange protocol
5 * (c) 2001 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Trivial IP Encryption (TrIPE).
12 * TrIPE is free software: you can redistribute it and/or modify it under
13 * the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your
15 * option) any later version.
17 * TrIPE is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
22 * You should have received a copy of the GNU General Public License
23 * along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
26 /*----- Header files ------------------------------------------------------*/
30 /*----- Brief protocol overview -------------------------------------------*
32 * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let
33 * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote
34 * application of the symmetric packet protocol to a message; let
35 * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$%
36 * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$%
37 * be Bob's public key.
39 * At the beginning of the session, Alice chooses
41 * %$\rho_A \inr \{0, \ldots q - 1\}$%
45 * %$r_A = g^{\rho_A}$% Alice's challenge
46 * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie
47 * %$v_A = \rho_A \xor H(\cookie{expected-reply}, a, r_A, r_B, b^{\rho_A})$%
48 * Alice's challenge check value
49 * %$r_B^\alpha = a^{\rho_B}$% Alice's reply
50 * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$%
51 * Alice and Bob's shared secret key
52 * %$w_A = H(\cookie{switch-request}, c_A, c_B)$%
53 * Alice's switch request value
54 * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$%
55 * Alice's switch confirm value
57 * The messages are then:
59 * %$\cookie{kx-pre-challenge}, r_A$%
60 * Initial greeting. In state @KXS_CHAL@.
62 * %$\cookie{kx-challenge}, r_A, c_B, v_A$%
63 * Here's a full challenge for you to answer.
65 * %$\cookie{kx-reply}, r_A, c_B, v_A, E_K(r_B^\alpha))$%
66 * Challenge accpeted: here's the answer. Commit to my challenge. Move
69 * %$\cookie{kx-switch-rq}, c_A, c_B, E_K(r_B^\alpha, w_A))$%
70 * Reply received: here's my reply. Committed; send data; move to
73 * %$\cookie{kx-switch-ok}, E_K(u_A))$%
74 * Switch received. Committed; send data; move to @KXS_SWITCH@.
77 /*----- Static tables -----------------------------------------------------*/
79 static const char *const pkname
[] = {
80 "pre-challenge", "challenge", "reply", "switch-rq", "switch-ok"
83 /*----- Various utilities -------------------------------------------------*/
87 * Arguments: @const keyexch *kx@ = key exchange state
88 * @time_t now@ = current time in seconds
90 * Returns: Whether the challenge in the key-exchange state is still
91 * valid or should be regenerated.
94 #define VALIDP(kx, now) ((now) < (kx)->t_valid)
98 * Arguments: @ghash *h@ = pointer to hash context
99 * @const dhgrp *g@ = pointer to group
100 * @const dhge *Y@ = pointer to group element
104 * Use: Adds the hash of a group element to the context. Corrupts
108 static void hashge(ghash
*h
, const dhgrp
*g
, const dhge
*Y
)
112 buf_init(&b
, buf_t
, sizeof(buf_t
));
113 g
->ops
->stge(g
, &b
, Y
, DHFMT_HASH
);
115 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
118 /* --- @mpmask@ --- *
120 * Arguments: @buf *b@ = output buffer
121 * @const dhgrp *g@ = the group
122 * @const dhsc *x@ = the plaintext scalar
123 * @size_t n@ = the expected size of the plaintext
124 * @gcipher *mgfc@ = mask-generating function to use
125 * @const octet *k@ = pointer to key material
126 * @size_t ksz@ = size of the key
130 * Use: Masks a scalar: returns %$x \xor H(k)$%, so it's a random
131 * oracle thing rather than an encryption thing. Breaks the
132 * output buffer on error.
135 static void mpmask(buf
*b
, const dhgrp
*g
, const dhsc
*x
, size_t n
,
136 const gccipher
*mgfc
, const octet
*k
, size_t ksz
)
141 if ((p
= buf_get(b
, n
)) == 0) return;
142 mgf
= GC_INIT(mgfc
, k
, ksz
);
143 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
144 trace(T_CRYPTO
, "crypto: masking scalar = %s", g
->ops
->scstr(g
, x
));
145 trace_block(T_CRYPTO
, "crypto: masking key", k
, ksz
);
147 if (g
->ops
->stsc(g
, buf_t
, n
, x
)) { buf_break(b
); return; }
148 GC_ENCRYPT(mgf
, buf_t
, p
, n
);
149 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
150 trace_block(T_CRYPTO
, "crypto: scalar plaintext", buf_t
, n
);
151 trace_block(T_CRYPTO
, "crypto: masked ciphertext", p
, n
);
156 /* --- @mpunmask@ --- *
158 * Arguments: @const dhgrp *g@ = the group
159 * @const octet *p@ = pointer to the ciphertext
160 * @size_t n@ = the size of the ciphertext
161 * @gcipher *mgfc@ = mask-generating function to use
162 * @const octet *k@ = pointer to key material
163 * @size_t ksz@ = size of the key
165 * Returns: The decrypted scalar, or null.
167 * Use: Unmasks a scalar.
170 static dhsc
*mpunmask(const dhgrp
*g
, const octet
*p
, size_t n
,
171 const gccipher
*mgfc
, const octet
*k
, size_t ksz
)
176 mgf
= GC_INIT(mgfc
, k
, ksz
);
177 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
178 trace_block(T_CRYPTO
, "crypto: unmasking key", k
, ksz
);
179 trace_block(T_CRYPTO
, "crypto: masked ciphertext", p
, n
);
181 GC_DECRYPT(mgf
, p
, buf_t
, n
);
182 x
= g
->ops
->ldsc(g
, buf_t
, n
);
183 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
184 trace_block(T_CRYPTO
, "crypto: scalar plaintext", buf_t
, n
);
185 trace(T_CRYPTO
, "crypto: unmasked scalar = %s",
186 x ? g
->ops
->scstr(g
, x
) : "<failed>");
192 /* --- @hashcheck@ --- *
194 * Arguments: @keyexch *kx@ = pointer to key-exchange block
195 * @const dhge *K@ = sender's public key
196 * @const dhge *CC@ = receiver's challenge
197 * @const dhge *C@ = sender's challenge
198 * @const dhge *Y@ = reply to sender's challenge
200 * Returns: Pointer to the hash value (in @buf_t@)
202 * Use: Computes the check-value hash, used to mask or unmask
203 * indices to prove the validity of challenges. This computes
204 * the masking key used in challenge check values. This is
205 * really the heart of the whole thing, since it ensures that
206 * the scalar can be recovered from the history of hashing
207 * queries, which gives us (a) a proof that the authentication
208 * process is zero-knowledge, and (b) a proof that the whole
209 * key-exchange is deniable.
212 static const octet
*hashcheck(keyexch
*kx
, const dhge
*K
,
213 const dhge
*CC
, const dhge
*C
, const dhge
*Y
)
215 ghash
*h
= GH_INIT(kx
->kpriv
->algs
.h
);
216 const dhgrp
*g
= kx
->kpriv
->grp
;
218 HASH_STRING(h
, "tripe-expected-reply");
224 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
225 trace(T_CRYPTO
, "crypto: computing challenge check hash");
226 trace(T_CRYPTO
, "crypto: public key = %s", g
->ops
->gestr(g
, K
));
227 trace(T_CRYPTO
, "crypto: receiver challenge = %s", g
->ops
->gestr(g
, CC
));
228 trace(T_CRYPTO
, "crypto: sender challenge = %s", g
->ops
->gestr(g
, C
));
229 trace(T_CRYPTO
, "crypto: sender reply = %s", g
->ops
->gestr(g
, Y
));
230 trace_block(T_CRYPTO
, "crypto: hash output", buf_t
, kx
->kpriv
->algs
.hashsz
);
236 /* --- @sendchallenge@ --- *
238 * Arguments: @keyexch *kx@ = pointer to key exchange block
239 * @buf *b@ = output buffer for challenge
240 * @const dhge *C@ = peer's actual challenge
241 * @const octet *hc@ = peer's challenge cookie
245 * Use: Writes a full challenge to the message buffer.
248 static void sendchallenge(keyexch
*kx
, buf
*b
,
249 const dhge
*C
, const octet
*hc
)
251 const dhgrp
*g
= kx
->kpriv
->grp
;
252 g
->ops
->stge(g
, b
, kx
->C
, DHFMT_VAR
);
253 buf_put(b
, hc
, kx
->kpriv
->algs
.hashsz
);
254 mpmask(b
, g
, kx
->a
, g
->scsz
, kx
->kpriv
->algs
.mgf
,
255 hashcheck(kx
, kx
->kpriv
->K
, C
, kx
->C
, kx
->RX
),
256 kx
->kpriv
->algs
.hashsz
);
261 * Arguments: @struct timeval *tv@ = the current time
262 * @void *v@ = pointer to key exchange context
266 * Use: Acts when the key exchange timer goes off.
269 static void timer(struct timeval
*tv
, void *v
)
273 T( trace(T_KEYEXCH
, "keyexch: timer has popped"); )
277 /* --- @settimer@ --- *
279 * Arguments: @keyexch *kx@ = pointer to key exchange context
280 * @struct timeval *tv@ = when to set the timer for
284 * Use: Sets the timer for the next key exchange attempt.
287 static void settimer(keyexch
*kx
, struct timeval
*tv
)
289 if (kx
->f
& KXF_TIMER
) sel_rmtimer(&kx
->t
);
290 sel_addtimer(&sel
, &kx
->t
, tv
, timer
, kx
);
296 * Arguments: @struct timeval *tv@ = where to write the timeval
297 * @double t@ = a time as a floating point number
301 * Use: Converts a floating-point time into a timeval.
304 static void f2tv(struct timeval
*tv
, double t
)
307 tv
->tv_usec
= (t
- tv
->tv_sec
)*MILLION
;
310 /* --- @wobble@ --- *
312 * Arguments: @double t@ = a time interval
314 * Returns: The same time interval, with a random error applied.
317 static double wobble(double t
)
319 uint32 r
= rand_global
.ops
->word(&rand_global
);
320 double w
= (r
/F_2P32
) - 0.5;
321 return (t
+ t
*w
*T_WOBBLE
);
324 /* --- @rs_time@ --- *
326 * Arguments: @retry *rs@ = current retry state
327 * @struct timeval *tv@ = where to write the result
328 * @const struct timeval *now@ = current time, or null
332 * Use: Computes a time at which to retry sending a key-exchange
333 * packet. This algorithm is subject to change, but it's
334 * currently a capped exponential backoff, slightly randomized
335 * to try to keep clients from hammering a server that's only
338 * If @now@ is null then the function works out the time for
342 static void rs_time(retry
*rs
, struct timeval
*tv
, const struct timeval
*now
)
351 if (t
> MIN(5)) t
= MIN(5);
359 f2tv(&rtv
, wobble(t
));
360 TV_ADD(tv
, now
, &rtv
);
363 /* --- @retry_reset@ --- *
365 * Arguments: @retry *rs@ = retry state
369 * Use: Resets a retry state to indicate that progress has been
370 * made. Also useful for initializing the state in the first
374 static void rs_reset(retry
*rs
) { rs
->t
= 0; }
376 /* --- @notice_message@ --- *
378 * Arguments: @keyexch *kx@ = pointer to key-exchange block
380 * Returns: Zero if OK; @-1@ if the public key is in a bad state.
382 * Use: Updates the key-exchange state following a received message.
383 * Specifically, if there's no currently active key-exchange in
384 * progress, and we're not in the cooling-off period, then
385 * commence a new one; reset the retry timers; and if we're
386 * corked then pop the cork so that we can reply.
389 static int checkpub(keyexch
*kx
);
390 static void stop(keyexch
*kx
);
391 static void start(keyexch
*kx
, time_t now
);
393 static int notice_message(keyexch
*kx
)
395 struct timeval now
, tv
;
397 gettimeofday(&now
, 0);
399 if (kx
->f
& KXF_CORK
) {
400 start(kx
, now
.tv_sec
);
401 rs_time(&kx
->rs
, &tv
, &now
);
403 a_notify("KXSTART", "?PEER", kx
->p
, A_END
);
405 if (checkpub(kx
)) return (-1);
406 if (!VALIDP(kx
, now
.tv_sec
)) {
408 start(kx
, now
.tv_sec
);
413 /* --- @update_stats_tx@, @update_stats_rx@ --- *
415 * Arguments: @keyexch *kx@ = pointer to key-exchange block
416 * @int ok@ = nonzero if the message was valid (for @rx@)
417 * @size_t sz@ = size of sent message
421 * Use: Records that a key-exchange message was sent to, or received
425 static void update_stats_tx(keyexch
*kx
, size_t sz
)
426 { stats
*st
= p_stats(kx
->p
); st
->n_kxout
++; st
->sz_kxout
+= sz
; }
428 static void update_stats_rx(keyexch
*kx
, int ok
, size_t sz
)
430 stats
*st
= p_stats(kx
->p
);
432 if (!ok
) st
->n_reject
++;
433 else { st
->n_kxin
++; st
->sz_kxin
+= sz
; }
436 /*----- Challenge management ----------------------------------------------*/
438 /* --- Notes on challenge management --- *
440 * We may get multiple different replies to our key exchange; some will be
441 * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges
442 * received will be added to the table and given a full response. After
443 * @KX_THRESH@ distinct challenges are received, we return only a `cookie':
444 * our existing challenge, followed by a hash of the sender's challenge. We
445 * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All
446 * properly-formed cookies are assigned a table slot: if none is spare, a
447 * used slot is randomly selected and destroyed. A cookie always receives a
451 /* --- @kxc_destroy@ --- *
453 * Arguments: @kxchal *kxc@ = pointer to the challenge block
457 * Use: Disposes of a challenge block.
460 static void kxc_destroy(kxchal
*kxc
)
462 const dhgrp
*g
= kxc
->kx
->kpriv
->grp
;
463 if (kxc
->f
& KXF_TIMER
)
464 sel_rmtimer(&kxc
->t
);
465 g
->ops
->freege(g
, kxc
->C
);
466 g
->ops
->freege(g
, kxc
->R
);
471 /* --- @kxc_stoptimer@ --- *
473 * Arguments: @kxchal *kxc@ = pointer to the challenge block
477 * Use: Stops the challenge's retry timer from sending messages.
478 * Useful when the state machine is in the endgame of the
482 static void kxc_stoptimer(kxchal
*kxc
)
484 if (kxc
->f
& KXF_TIMER
)
485 sel_rmtimer(&kxc
->t
);
486 kxc
->f
&= ~KXF_TIMER
;
489 /* --- @kxc_new@ --- *
491 * Arguments: @keyexch *kx@ = pointer to key exchange block
493 * Returns: A pointer to the challenge block.
495 * Use: Returns a pointer to a new challenge block to fill in.
496 * In particular, the @c@ and @r@ members are left
500 static kxchal
*kxc_new(keyexch
*kx
)
505 /* --- If we're over reply threshold, discard one at random --- */
507 if (kx
->nr
< KX_NCHAL
)
510 i
= rand_global
.ops
->range(&rand_global
, KX_NCHAL
);
511 kxc_destroy(kx
->r
[i
]);
514 /* --- Fill in the new structure --- */
516 kxc
= CREATE(kxchal
);
525 /* --- @kxc_bychal@ --- *
527 * Arguments: @keyexch *kx@ = pointer to key exchange block
528 * @const dhge *C@ = challenge from remote host
530 * Returns: Pointer to the challenge block, or null.
532 * Use: Finds a challenge block, given its challenge.
535 static kxchal
*kxc_bychal(keyexch
*kx
, const dhge
*C
)
537 const dhgrp
*g
= kx
->kpriv
->grp
;
540 for (i
= 0; i
< kx
->nr
; i
++) {
541 if (g
->ops
->eq(g
, C
, kx
->r
[i
]->C
))
547 /* --- @kxc_byhc@ --- *
549 * Arguments: @keyexch *kx@ = pointer to key exchange block
550 * @const octet *hc@ = challenge hash from remote host
552 * Returns: Pointer to the challenge block, or null.
554 * Use: Finds a challenge block, given a hash of its challenge.
557 static kxchal
*kxc_byhc(keyexch
*kx
, const octet
*hc
)
561 for (i
= 0; i
< kx
->nr
; i
++) {
562 if (memcmp(hc
, kx
->r
[i
]->hc
, kx
->kpriv
->algs
.hashsz
) == 0)
568 /* --- @kxc_answer@ --- *
570 * Arguments: @keyexch *kx@ = pointer to key exchange block
571 * @kxchal *kxc@ = pointer to challenge block
575 * Use: Sends a reply to the remote host, according to the data in
576 * this challenge block.
579 static void kxc_answer(keyexch
*kx
, kxchal
*kxc
);
581 static void kxc_timer(struct timeval
*tv
, void *v
)
584 kxc
->f
&= ~KXF_TIMER
;
585 kxc_answer(kxc
->kx
, kxc
);
588 static void kxc_answer(keyexch
*kx
, kxchal
*kxc
)
590 buf
*b
= p_txstart(kx
->p
, MSG_KEYEXCH
| KX_REPLY
);
591 const dhgrp
*g
= kx
->kpriv
->grp
;
595 /* --- Build the reply packet --- */
597 T( trace(T_KEYEXCH
, "keyexch: sending reply to `%s'", p_name(kx
->p
)); )
598 sendchallenge(kx
, b
, kxc
->C
, kxc
->hc
);
599 buf_init(&bb
, buf_i
, sizeof(buf_i
));
600 g
->ops
->stge(g
, &bb
, kxc
->R
, DHFMT_STD
);
602 ks_encrypt(kxc
->ks
, MSG_KEYEXCH
| KX_REPLY
, &bb
, b
);
604 /* --- Update the statistics --- */
607 update_stats_tx(kx
, BLEN(b
));
611 /* --- Schedule another resend --- */
613 if (kxc
->f
& KXF_TIMER
)
614 sel_rmtimer(&kxc
->t
);
615 gettimeofday(&tv
, 0);
616 rs_time(&kxc
->rs
, &tv
, &tv
);
617 sel_addtimer(&sel
, &kxc
->t
, &tv
, kxc_timer
, kxc
);
621 /*----- Individual message handlers ---------------------------------------*/
623 /* --- @doprechallenge@ --- *
625 * Arguments: @keyexch *kx@ = pointer to key exchange block
626 * @buf *b@ = buffer containing the packet
628 * Returns: Zero if OK, nonzero of the packet was rejected.
630 * Use: Processes a pre-challenge message.
633 static int doprechallenge(keyexch
*kx
, buf
*b
)
635 const dhgrp
*g
= kx
->kpriv
->grp
;
639 /* --- Ensure that we're in a sensible state --- */
641 if (kx
->s
!= KXS_CHAL
) {
642 a_warn("KX", "?PEER", kx
->p
, "unexpected", "pre-challenge", A_END
);
646 /* --- Unpack the packet --- */
648 if ((C
= g
->ops
->ldge(g
, b
, DHFMT_VAR
)) == 0 || BLEFT(b
))
651 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
652 trace(T_CRYPTO
, "crypto: challenge = %s", g
->ops
->gestr(g
, C
));
655 /* --- Send out a full challenge by return --- */
657 b
= p_txstart(kx
->p
, MSG_KEYEXCH
| KX_CHAL
);
658 h
= GH_INIT(kx
->kpriv
->algs
.h
);
659 HASH_STRING(h
, "tripe-cookie");
661 sendchallenge(kx
, b
, C
, GH_DONE(h
, 0));
663 update_stats_tx(kx
, BLEN(b
));
668 g
->ops
->freege(g
, C
);
672 if (C
) g
->ops
->freege(g
, C
);
676 /* --- @respond@ --- *
678 * Arguments: @keyexch *kx@ = pointer to key exchange block
679 * @unsigned msg@ = message code for this packet
680 * @buf *b@ = buffer containing the packet
682 * Returns: Key-exchange challenge block, or null.
684 * Use: Computes a response for the given challenge, entering it into
685 * a challenge block and so on.
688 static kxchal
*respond(keyexch
*kx
, unsigned msg
, buf
*b
)
690 const dhgrp
*g
= kx
->kpriv
->grp
;
691 const algswitch
*algs
= &kx
->kpriv
->algs
;
692 size_t ixsz
= g
->scsz
;
697 const octet
*hc
, *ck
;
704 /* --- Unpack the packet --- */
706 if ((C
= g
->ops
->ldge(g
, b
, DHFMT_VAR
)) == 0 ||
707 (hc
= buf_get(b
, algs
->hashsz
)) == 0 ||
708 (ck
= buf_get(b
, ixsz
)) == 0) {
709 a_warn("KX", "?PEER", kx
->p
, "invalid", "%s", pkname
[msg
], A_END
);
712 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
713 trace(T_CRYPTO
, "crypto: challenge = %s", g
->ops
->gestr(g
, C
));
714 trace_block(T_CRYPTO
, "crypto: cookie", hc
, algs
->hashsz
);
715 trace_block(T_CRYPTO
, "crypto: check-value", ck
, ixsz
);
718 /* --- Discard a packet with an invalid cookie --- */
720 if (hc
&& memcmp(hc
, kx
->hc
, algs
->hashsz
) != 0) {
721 a_warn("KX", "?PEER", kx
->p
, "incorrect", "cookie", A_END
);
725 /* --- Recover the check value and verify it --- *
727 * To avoid recomputation on replays, we store a hash of the `right'
728 * value. The `correct' value is unique, so this is right.
730 * This will also find a challenge block and, if necessary, populate it.
733 if ((kxc
= kxc_bychal(kx
, C
)) != 0) {
734 h
= GH_INIT(algs
->h
);
735 HASH_STRING(h
, "tripe-check-hash");
736 GH_HASH(h
, ck
, ixsz
);
737 ok
= !memcmp(kxc
->ck
, GH_DONE(h
, 0), algs
->hashsz
);
739 if (!ok
) goto badcheck
;
742 /* --- Compute the reply, and check the magic --- */
744 R
= g
->ops
->mul(g
, kx
->kpriv
->k
, C
);
745 if ((c
= mpunmask(g
, ck
, ixsz
, algs
->mgf
,
746 hashcheck(kx
, kx
->kpub
->K
, kx
->C
, C
, R
),
749 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
750 trace(T_CRYPTO
, "crypto: computed reply = %s", g
->ops
->gestr(g
, R
));
751 trace(T_CRYPTO
, "crypto: recovered log = %s", g
->ops
->scstr(g
, c
));
753 CC
= g
->ops
->mul(g
, c
, 0);
754 if (!g
->ops
->eq(g
, CC
, C
)) goto badcheck
;
756 /* --- Fill in a new challenge block --- */
762 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-check-hash");
763 GH_HASH(h
, ck
, ixsz
);
764 GH_DONE(h
, kxc
->ck
); GH_DESTROY(h
);
766 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-cookie");
767 hashge(h
, g
, kxc
->C
);
768 GH_DONE(h
, kxc
->hc
); GH_DESTROY(h
);
770 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
771 trace_block(T_CRYPTO
, "crypto: computed cookie",
772 kxc
->hc
, algs
->hashsz
);
775 /* --- Work out the shared key --- */
777 R
= g
->ops
->mul(g
, kx
->a
, kxc
->C
);
778 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
779 trace(T_CRYPTO
, "crypto: shared secret = %s", g
->ops
->gestr(g
, R
));
782 /* --- Compute the switch messages --- */
784 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-switch-request");
785 hashge(h
, g
, kx
->C
); hashge(h
, g
, kxc
->C
);
786 GH_DONE(h
, kxc
->hswrq_out
); GH_DESTROY(h
);
787 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-switch-confirm");
788 hashge(h
, g
, kx
->C
); hashge(h
, g
, kxc
->C
);
789 GH_DONE(h
, kxc
->hswok_out
); GH_DESTROY(h
);
791 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-switch-request");
792 hashge(h
, g
, kxc
->C
); hashge(h
, g
, kx
->C
);
793 GH_DONE(h
, kxc
->hswrq_in
); GH_DESTROY(h
);
794 h
= GH_INIT(algs
->h
); HASH_STRING(h
, "tripe-switch-confirm");
795 hashge(h
, g
, kxc
->C
); hashge(h
, g
, kx
->C
);
796 GH_DONE(h
, kxc
->hswok_in
); GH_DESTROY(h
);
798 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
799 trace_block(T_CRYPTO
, "crypto: outbound switch request",
800 kxc
->hswrq_out
, algs
->hashsz
);
801 trace_block(T_CRYPTO
, "crypto: outbound switch confirm",
802 kxc
->hswok_out
, algs
->hashsz
);
803 trace_block(T_CRYPTO
, "crypto: inbound switch request",
804 kxc
->hswrq_in
, algs
->hashsz
);
805 trace_block(T_CRYPTO
, "crypto: inbound switch confirm",
806 kxc
->hswok_in
, algs
->hashsz
);
809 /* --- Create a new symmetric keyset --- */
811 buf_init(&bb
, buf_o
, sizeof(buf_o
)); a
.k
= BBASE(&bb
);
812 g
->ops
->stge(g
, &bb
, kx
->C
, DHFMT_HASH
); a
.x
= BLEN(&bb
);
813 g
->ops
->stge(g
, &bb
, kxc
->C
, DHFMT_HASH
); a
.y
= BLEN(&bb
);
814 g
->ops
->stge(g
, &bb
, R
, DHFMT_HASH
); a
.z
= BLEN(&bb
);
817 kxc
->ks
= ks_gen(&a
, kx
->p
);
820 if (C
) g
->ops
->freege(g
, C
);
821 if (CC
) g
->ops
->freege(g
, CC
);
822 if (R
) g
->ops
->freege(g
, R
);
823 if (c
) g
->ops
->freesc(g
, c
);
827 a_warn("KX", "?PEER", kx
->p
, "bad-expected-reply-log", A_END
);
830 if (C
) g
->ops
->freege(g
, C
);
831 if (CC
) g
->ops
->freege(g
, CC
);
832 if (R
) g
->ops
->freege(g
, R
);
833 if (c
) g
->ops
->freesc(g
, c
);
837 /* --- @dochallenge@ --- *
839 * Arguments: @keyexch *kx@ = pointer to key exchange block
840 * @unsigned msg@ = message code for the packet
841 * @buf *b@ = buffer containing the packet
843 * Returns: Zero if OK, nonzero if the packet was rejected.
845 * Use: Processes a packet containing a challenge.
848 static int dochallenge(keyexch
*kx
, buf
*b
)
852 if (kx
->s
!= KXS_CHAL
) {
853 a_warn("KX", "?PEER", kx
->p
, "unexpected", "challenge", A_END
);
856 if ((kxc
= respond(kx
, KX_CHAL
, b
)) == 0)
859 a_warn("KX", "?PEER", kx
->p
, "invalid", "challenge", A_END
);
869 /* --- @resend@ --- *
871 * Arguments: @keyexch *kx@ = pointer to key exchange context
875 * Use: Sends the next message for a key exchange.
878 static void resend(keyexch
*kx
)
883 const dhgrp
*g
= kx
->kpriv
->grp
;
888 T( trace(T_KEYEXCH
, "keyexch: sending prechallenge to `%s'",
890 b
= p_txstart(kx
->p
, MSG_KEYEXCH
| KX_PRECHAL
);
891 g
->ops
->stge(g
, b
, kx
->C
, DHFMT_VAR
);
894 T( trace(T_KEYEXCH
, "keyexch: sending switch request to `%s'",
897 b
= p_txstart(kx
->p
, MSG_KEYEXCH
| KX_SWITCH
);
898 buf_put(b
, kx
->hc
, kx
->kpriv
->algs
.hashsz
);
899 buf_put(b
, kxc
->hc
, kx
->kpriv
->algs
.hashsz
);
900 buf_init(&bb
, buf_i
, sizeof(buf_i
));
901 g
->ops
->stge(g
, &bb
, kxc
->R
, DHFMT_STD
);
902 buf_put(&bb
, kxc
->hswrq_out
, kx
->kpriv
->algs
.hashsz
);
904 ks_encrypt(kxc
->ks
, MSG_KEYEXCH
| KX_SWITCH
, &bb
, b
);
907 T( trace(T_KEYEXCH
, "keyexch: sending switch confirmation to `%s'",
910 b
= p_txstart(kx
->p
, MSG_KEYEXCH
| KX_SWITCHOK
);
911 buf_init(&bb
, buf_i
, sizeof(buf_i
));
912 buf_put(&bb
, kxc
->hswok_out
, kx
->kpriv
->algs
.hashsz
);
914 ks_encrypt(kxc
->ks
, MSG_KEYEXCH
| KX_SWITCHOK
, &bb
, b
);
921 update_stats_tx(kx
, BLEN(b
));
925 if (kx
->s
< KXS_SWITCH
) {
926 rs_time(&kx
->rs
, &tv
, 0);
931 /* --- @decryptrest@ --- *
933 * Arguments: @keyexch *kx@ = pointer to key exchange context
934 * @kxchal *kxc@ = pointer to challenge block
935 * @unsigned msg@ = type of incoming message
936 * @buf *b@ = encrypted remainder of the packet
938 * Returns: Zero if OK, nonzero on some kind of error.
940 * Use: Decrypts the remainder of the packet, and points @b@ at the
941 * recovered plaintext.
944 static int decryptrest(keyexch
*kx
, kxchal
*kxc
, unsigned msg
, buf
*b
)
948 buf_init(&bb
, buf_o
, sizeof(buf_o
));
949 if (ks_decrypt(kxc
->ks
, MSG_KEYEXCH
| msg
, b
, &bb
)) {
950 a_warn("KX", "?PEER", kx
->p
, "decrypt-failed", "%s", pkname
[msg
], A_END
);
953 if (!BOK(&bb
)) return (-1);
954 buf_init(b
, BBASE(&bb
), BLEN(&bb
));
958 /* --- @checkresponse@ --- *
960 * Arguments: @keyexch *kx@ = pointer to key exchange context
961 * @unsigned msg@ = type of incoming message
962 * @buf *b@ = decrypted remainder of the packet
964 * Returns: Zero if OK, nonzero on some kind of error.
966 * Use: Checks a reply or switch packet, ensuring that its response
970 static int checkresponse(keyexch
*kx
, unsigned msg
, buf
*b
)
972 const dhgrp
*g
= kx
->kpriv
->grp
;
975 if ((R
= g
->ops
->ldge(g
, b
, DHFMT_STD
)) == 0) {
976 a_warn("KX", "?PEER", kx
->p
, "invalid", "%s", pkname
[msg
], A_END
);
979 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
980 trace(T_CRYPTO
, "crypto: reply = %s", g
->ops
->gestr(g
, R
));
982 if (!g
->ops
->eq(g
, R
, kx
->RX
)) {
983 a_warn("KX", "?PEER", kx
->p
, "incorrect", "response", A_END
);
987 g
->ops
->freege(g
, R
);
991 if (R
) g
->ops
->freege(g
, R
);
995 /* --- @commit@ --- *
997 * Arguments: @keyexch *kx@ = pointer to key exchange context
998 * @kxchal *kxc@ = pointer to challenge to commit to
1002 * Use: Commits to a particular challenge as being the `right' one,
1003 * since a reply has arrived for it.
1006 static void commit(keyexch
*kx
, kxchal
*kxc
)
1010 for (i
= 0; i
< kx
->nr
; i
++) {
1011 if (kx
->r
[i
] != kxc
)
1012 kxc_destroy(kx
->r
[i
]);
1017 ksl_link(kx
->ks
, kxc
->ks
);
1020 /* --- @doreply@ --- *
1022 * Arguments: @keyexch *kx@ = pointer to key exchange context
1023 * @buf *b@ = buffer containing packet
1025 * Returns: Zero if OK, nonzero if the packet was rejected.
1027 * Use: Handles a reply packet. This doesn't handle the various
1028 * switch packets: they're rather too different.
1031 static int doreply(keyexch
*kx
, buf
*b
)
1035 if (kx
->s
!= KXS_CHAL
&& kx
->s
!= KXS_COMMIT
) {
1036 a_warn("KX", "?PEER", kx
->p
, "unexpected", "reply", A_END
);
1039 if ((kxc
= respond(kx
, KX_REPLY
, b
)) == 0 ||
1040 decryptrest(kx
, kxc
, KX_REPLY
, b
) ||
1041 checkresponse(kx
, KX_REPLY
, b
))
1044 a_warn("KX", "?PEER", kx
->p
, "invalid", "reply", A_END
);
1047 if (kx
->s
== KXS_CHAL
) {
1058 /* --- @kxfinish@ --- *
1060 * Arguments: @keyexch *kx@ = pointer to key exchange block
1064 * Use: Sets everything up following a successful key exchange.
1067 static void kxfinish(keyexch
*kx
)
1069 kxchal
*kxc
= kx
->r
[0];
1070 struct timeval now
, tv
;
1072 ks_activate(kxc
->ks
);
1073 gettimeofday(&now
, 0);
1074 f2tv(&tv
, wobble(T_REGEN
));
1075 TV_ADD(&tv
, &now
, &tv
);
1078 a_notify("KXDONE", "?PEER", kx
->p
, A_END
);
1079 p_stats(kx
->p
)->t_kx
= time(0);
1082 /* --- @doswitch@ --- *
1084 * Arguments: @keyexch *kx@ = pointer to key exchange block
1085 * @buf *b@ = pointer to buffer containing packet
1087 * Returns: Zero if OK, nonzero if the packet was rejected.
1089 * Use: Handles a reply with a switch request bolted onto it.
1092 static int doswitch(keyexch
*kx
, buf
*b
)
1094 size_t hsz
= kx
->kpriv
->algs
.hashsz
;
1095 const octet
*hc_in
, *hc_out
, *hswrq
;
1098 if ((hc_in
= buf_get(b
, hsz
)) == 0 ||
1099 (hc_out
= buf_get(b
, hsz
)) == 0) {
1100 a_warn("KX", "?PEER", kx
->p
, "invalid", "switch-rq", A_END
);
1103 IF_TRACING(T_KEYEXCH
, IF_TRACING(T_CRYPTO
, {
1104 trace_block(T_CRYPTO
, "crypto: challenge", hc_in
, hsz
);
1105 trace_block(T_CRYPTO
, "crypto: cookie", hc_out
, hsz
);
1107 if ((kxc
= kxc_byhc(kx
, hc_in
)) == 0 ||
1108 memcmp(hc_out
, kx
->hc
, hsz
) != 0) {
1109 a_warn("KX", "?PEER", kx
->p
, "incorrect", "switch-rq", A_END
);
1112 if (decryptrest(kx
, kxc
, KX_SWITCH
, b
) ||
1113 checkresponse(kx
, KX_SWITCH
, b
))
1115 if ((hswrq
= buf_get(b
, hsz
)) == 0 || BLEFT(b
)) {
1116 a_warn("KX", "?PEER", kx
->p
, "invalid", "switch-rq", A_END
);
1119 IF_TRACING(T_KEYEXCH
, {
1120 trace_block(T_CRYPTO
, "crypto: switch request hash", hswrq
, hsz
);
1122 if (memcmp(hswrq
, kxc
->hswrq_in
, hsz
) != 0) {
1123 a_warn("KX", "?PEER", kx
->p
, "incorrect", "switch-rq", A_END
);
1126 if (kx
->s
== KXS_CHAL
)
1128 if (kx
->s
< KXS_SWITCH
)
1137 /* --- @doswitchok@ --- *
1139 * Arguments: @keyexch *kx@ = pointer to key exchange block
1140 * @buf *b@ = pointer to buffer containing packet
1142 * Returns: Zero if OK, nonzero if the packet was rejected.
1144 * Use: Handles a reply with a switch request bolted onto it.
1147 static int doswitchok(keyexch
*kx
, buf
*b
)
1149 size_t hsz
= kx
->kpriv
->algs
.hashsz
;
1154 if (kx
->s
< KXS_COMMIT
) {
1155 a_warn("KX", "?PEER", kx
->p
, "unexpected", "switch-ok", A_END
);
1159 buf_init(&bb
, buf_o
, sizeof(buf_o
));
1160 if (decryptrest(kx
, kxc
, KX_SWITCHOK
, b
))
1162 if ((hswok
= buf_get(b
, hsz
)) == 0 || BLEFT(b
)) {
1163 a_warn("KX", "?PEER", kx
->p
, "invalid", "switch-ok", A_END
);
1166 IF_TRACING(T_KEYEXCH
, {
1167 trace_block(T_CRYPTO
, "crypto: switch confirmation hash",
1170 if (memcmp(hswok
, kxc
->hswok_in
, hsz
) != 0) {
1171 a_warn("KX", "?PEER", kx
->p
, "incorrect", "switch-ok", A_END
);
1174 if (kx
->s
< KXS_SWITCH
)
1182 /*----- Main code ---------------------------------------------------------*/
1186 * Arguments: @keyexch *kx@ = pointer to key exchange context
1190 * Use: Stops a key exchange dead in its tracks. Throws away all of
1191 * the context information. The context is left in an
1192 * inconsistent state. The only functions which understand this
1193 * state are @kx_free@ and @kx_init@ (which cause it internally
1194 * it), and @start@ (which expects it to be the prevailing
1198 static void stop(keyexch
*kx
)
1200 const dhgrp
*g
= kx
->kpriv
->grp
;
1203 if (kx
->f
& KXF_DEAD
)
1206 if (kx
->f
& KXF_TIMER
)
1207 sel_rmtimer(&kx
->t
);
1208 for (i
= 0; i
< kx
->nr
; i
++)
1209 kxc_destroy(kx
->r
[i
]);
1210 g
->ops
->freesc(g
, kx
->a
);
1211 g
->ops
->freege(g
, kx
->C
);
1212 g
->ops
->freege(g
, kx
->RX
);
1215 kx
->f
&= ~KXF_TIMER
;
1218 /* --- @start@ --- *
1220 * Arguments: @keyexch *kx@ = pointer to key exchange context
1221 * @time_t now@ = the current time
1225 * Use: Starts a new key exchange with the peer. The context must be
1226 * in the bizarre state left by @stop@ or @kx_init@.
1229 static void start(keyexch
*kx
, time_t now
)
1231 algswitch
*algs
= &kx
->kpriv
->algs
;
1232 const dhgrp
*g
= kx
->kpriv
->grp
;
1235 assert(kx
->f
& KXF_DEAD
);
1237 kx
->f
&= ~(KXF_DEAD
| KXF_CORK
);
1239 kx
->a
= g
->ops
->randsc(g
);
1240 kx
->C
= g
->ops
->mul(g
, kx
->a
, 0);
1241 kx
->RX
= g
->ops
->mul(g
, kx
->a
, kx
->kpub
->K
);
1243 kx
->t_valid
= now
+ T_VALID
;
1245 h
= GH_INIT(algs
->h
);
1246 HASH_STRING(h
, "tripe-cookie");
1247 hashge(h
, g
, kx
->C
);
1251 IF_TRACING(T_KEYEXCH
, {
1252 trace(T_KEYEXCH
, "keyexch: creating new challenge");
1253 IF_TRACING(T_CRYPTO
, {
1254 trace(T_CRYPTO
, "crypto: secret = %s", g
->ops
->scstr(g
, kx
->a
));
1255 trace(T_CRYPTO
, "crypto: challenge = %s", g
->ops
->gestr(g
, kx
->C
));
1256 trace(T_CRYPTO
, "crypto: expected response = %s",
1257 g
->ops
->gestr(g
, kx
->RX
));
1258 trace_block(T_CRYPTO
, "crypto: challenge cookie",
1259 kx
->hc
, algs
->hashsz
);
1264 /* --- @checkpub@ --- *
1266 * Arguments: @keyexch *kx@ = pointer to key exchange context
1268 * Returns: Zero if OK, nonzero if the peer's public key has expired.
1270 * Use: Deactivates the key-exchange until the peer acquires a new
1274 static int checkpub(keyexch
*kx
)
1279 if (kx
->f
& KXF_DEAD
)
1282 if (KEY_EXPIRED(now
, kx
->kpriv
->t_exp
)) f
|= 1;
1283 if (KEY_EXPIRED(now
, kx
->kpub
->t_exp
)) f
|= 2;
1286 if (f
& 1) a_warn("KX", "?PEER", kx
->p
, "private-key-expired", A_END
);
1287 if (f
& 2) a_warn("KX", "?PEER", kx
->p
, "public-key-expired", A_END
);
1288 kx
->f
&= ~KXF_PUBKEY
;
1294 /* --- @kx_start@ --- *
1296 * Arguments: @keyexch *kx@ = pointer to key exchange context
1297 * @int forcep@ = nonzero to ignore the quiet timer
1301 * Use: Stimulates a key exchange. If a key exchage is in progress,
1302 * a new challenge is sent (unless the quiet timer forbids
1303 * this); if no exchange is in progress, one is commenced.
1306 void kx_start(keyexch
*kx
, int forcep
)
1308 time_t now
= time(0);
1312 if (forcep
|| !VALIDP(kx
, now
)) {
1315 a_notify("KXSTART", "?PEER", kx
->p
, A_END
);
1320 /* --- @kx_message@ --- *
1322 * Arguments: @keyexch *kx@ = pointer to key exchange context
1323 * @unsigned msg@ = the message code
1324 * @buf *b@ = pointer to buffer containing the packet
1328 * Use: Reads a packet containing key exchange messages and handles
1332 void kx_message(keyexch
*kx
, unsigned msg
, buf
*b
)
1337 if (notice_message(kx
)) return;
1339 T( trace(T_KEYEXCH
, "keyexch: processing %s packet from `%s'",
1340 msg
< KX_NMSG ? pkname
[msg
] : "unknown", p_name(kx
->p
)); )
1343 case KX_PRECHAL
: rc
= doprechallenge(kx
, b
); break;
1344 case KX_CHAL
: rc
= dochallenge(kx
, b
); break;
1345 case KX_REPLY
: rc
= doreply(kx
, b
); break;
1346 case KX_SWITCH
: rc
= doswitch(kx
, b
); break;
1347 case KX_SWITCHOK
: rc
= doswitchok(kx
, b
); break;
1349 a_warn("KX", "?PEER", kx
->p
, "unknown-message", "0x%02x", msg
, A_END
);
1354 update_stats_rx(kx
, !rc
, sz
);
1357 /* --- @kx_free@ --- *
1359 * Arguments: @keyexch *kx@ = pointer to key exchange context
1363 * Use: Frees everything in a key exchange context.
1366 void kx_free(keyexch
*kx
)
1370 km_unref(kx
->kpriv
);
1373 /* --- @kx_newkeys@ --- *
1375 * Arguments: @keyexch *kx@ = pointer to key exchange context
1379 * Use: Informs the key exchange module that its keys may have
1380 * changed. If fetching the new keys fails, the peer will be
1381 * destroyed, we log messages and struggle along with the old
1385 void kx_newkeys(keyexch
*kx
)
1387 kdata
*kpriv
, *kpub
;
1390 time_t now
= time(0);
1392 T( trace(T_KEYEXCH
, "keyexch: checking new keys for `%s'",
1395 /* --- Find out whether we can use new keys --- *
1397 * Try each available combination of new and old, public and private,
1398 * except both old (which is status quo anyway). The selection is encoded
1399 * in @i@, with bit 0 for the private key and bit 1 for public key; a set
1400 * bit means to use the old value, and a clear bit means to use the new
1403 * This means that we currently prefer `old private and new public' over
1404 * `new private and old public'. I'm not sure which way round this should
1408 for (i
= 0; i
< 3; i
++) {
1410 /* --- Select the keys we're going to examine --- *
1412 * If we're meant to have a new key and don't, then skip this
1416 T( trace(T_KEYEXCH
, "keyexch: checking %s private, %s public",
1417 i
& 1 ?
"old" : "new", i
& 2 ?
"old" : "new"); )
1419 if (i
& 1) kpriv
= kx
->kpriv
;
1420 else if (kx
->kpriv
->kn
->kd
!= kx
->kpriv
) kpriv
= kx
->kpriv
->kn
->kd
;
1422 T( trace(T_KEYEXCH
, "keyexch: private key unchanged, skipping"); )
1426 if (i
& 2) kpub
= kx
->kpub
;
1427 else if (kx
->kpub
->kn
->kd
!= kx
->kpub
) kpub
= kx
->kpub
->kn
->kd
;
1429 T( trace(T_KEYEXCH
, "keyexch: public key unchanged, skipping"); )
1433 /* --- Skip if either key is expired --- *
1435 * We're not going to get far with expired keys, and this simplifies the
1439 if (KEY_EXPIRED(now
, kx
->kpriv
->t_exp
) ||
1440 KEY_EXPIRED(now
, kx
->kpub
->t_exp
)) {
1441 T( trace(T_KEYEXCH
, "keyexch: %s expired, skipping",
1442 !KEY_EXPIRED(now
, kx
->kpriv
->t_exp
) ?
"public key" :
1443 !KEY_EXPIRED(now
, kx
->kpub
->t_exp
) ?
"private key" :
1448 /* --- If the groups don't match then we can't use this pair --- */
1450 if (!km_samealgsp(kpriv
, kpub
)) {
1451 T( trace(T_KEYEXCH
, "keyexch: peer `%s' group mismatch; "
1452 "%s priv `%s' and %s pub `%s'", p_name(kx
->p
),
1453 i
& 1 ?
"old" : "new", km_tag(kx
->kpriv
),
1454 i
& 2 ?
"old" : "new", km_tag(kx
->kpub
)); )
1459 T( trace(T_KEYEXCH
, "keyexch: peer `%s' continuing with old keys",
1463 /* --- We've chosen new keys --- *
1465 * Switch the new ones into place. Neither of the keys we're switching to
1466 * is expired (we checked that above), so we should just crank everything
1469 * A complication arises: we don't really want to force a new key exchange
1470 * unless we have to. If the group is unchanged, and we're currently
1471 * running OK, then we should just let things lie.
1475 switchp
= ((kx
->f
& KXF_DEAD
) ||
1476 kx
->s
!= KXS_SWITCH
||
1477 kpriv
->grp
->ops
!= kx
->kpriv
->grp
->ops
||
1478 !kpriv
->grp
->ops
->samegrpp(kpriv
->grp
, kx
->kpriv
->grp
));
1480 T( trace(T_KEYEXCH
, "keyexch: peer `%s' adopting "
1481 "%s priv `%s' and %s pub `%s'; %sforcing exchange", p_name(kx
->p
),
1482 i
& 1 ?
"old" : "new", km_tag(kx
->kpriv
),
1483 i
& 2 ?
"old" : "new", km_tag(kx
->kpub
),
1484 switchp ?
"" : "not "); )
1486 if (switchp
) stop(kx
);
1487 km_ref(kpriv
); km_unref(kx
->kpriv
); kx
->kpriv
= kpriv
;
1488 km_ref(kpub
); km_unref(kx
->kpub
); kx
->kpub
= kpub
;
1489 kx
->f
|= KXF_PUBKEY
;
1491 T( trace(T_KEYEXCH
, "keyexch: restarting key negotiation with `%s'",
1498 /* --- @kx_setup@ --- *
1500 * Arguments: @keyexch *kx@ = pointer to key exchange context
1501 * @peer *p@ = pointer to peer context
1502 * @keyset **ks@ = pointer to keyset list
1503 * @unsigned f@ = various useful flags
1505 * Returns: Zero if OK, nonzero if it failed.
1507 * Use: Initializes a key exchange module. The module currently
1508 * contains no keys, and will attempt to initiate a key
1512 int kx_setup(keyexch
*kx
, peer
*p
, keyset
**ks
, unsigned f
)
1514 if ((kx
->kpriv
= km_findpriv(p_privtag(p
))) == 0) goto fail_0
;
1515 if ((kx
->kpub
= km_findpub(p_tag(p
))) == 0) goto fail_1
;
1516 if (!km_samealgsp(kx
->kpriv
, kx
->kpub
)) {
1517 a_warn("KX", "?PEER", p
, "group-mismatch",
1518 "local-private-key", "%s", p_privtag(p
),
1519 "peer-public-key", "%s", p_tag(p
),
1526 kx
->f
= KXF_DEAD
| KXF_PUBKEY
| f
;
1528 if (!(kx
->f
& KXF_CORK
)) {
1531 /* Don't notify here: the ADD message hasn't gone out yet. */
1538 km_unref(kx
->kpriv
);
1543 /*----- That's all, folks -------------------------------------------------*/