3 * Key loading and storing
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
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.
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.
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.
27 /*----- Header files ------------------------------------------------------*/
31 /*----- Global variables --------------------------------------------------*/
39 /*----- Static variables --------------------------------------------------*/
41 static key_file *kf_pub;
42 static const char *kr_priv, *kr_pub, *tag_priv;
43 static fwatch w_priv, w_pub;
45 /*----- Key groups --------------------------------------------------------*/
47 typedef struct kgops {
49 const char *(*loadpriv)(key_data *, group **, mp **, dstr *);
50 const char *(*loadpub)(key_data *, group **, ge **, dstr *);
53 /* --- Diffie-Hellman --- */
55 static const char *kgdh_priv(key_data *kd, group **g, mp **x, dstr *t)
57 key_packstruct kps[DH_PRIVFETCHSZ];
63 kp = key_fetchinit(dh_privfetch, kps, &dp);
64 if ((rc = key_unpack(kp, kd, t)) != 0) {
68 *g = group_prime(&dp.dp);
76 static const char *kgdh_pub(key_data *kd, group **g, ge **p, dstr *t)
78 key_packstruct kps[DH_PUBFETCHSZ];
84 kp = key_fetchinit(dh_pubfetch, kps, &dp);
85 if ((rc = key_unpack(kp, kd, t)) != 0) {
89 *g = group_prime(&dp.dp);
91 if (G_FROMINT(*g, *p, dp.y)) {
92 e = "bad public value";
101 static const kgops kgdh_ops = { "dh", kgdh_priv, kgdh_pub };
103 /* --- Elliptic curve --- */
105 static const char *kgec_priv(key_data *kd, group **g, mp **x, dstr *t)
107 key_packstruct kps[EC_PRIVFETCHSZ];
114 kp = key_fetchinit(ec_privfetch, kps, &ep);
115 if ((rc = key_unpack(kp, kd, t)) != 0) {
116 e = key_strerror(rc);
119 if ((e = ec_getinfo(&ei, ep.cstr)) != 0)
129 static const char *kgec_pub(key_data *kd, group **g, ge **p, dstr *t)
131 key_packstruct kps[EC_PUBFETCHSZ];
138 kp = key_fetchinit(ec_pubfetch, kps, &ep);
139 if ((rc = key_unpack(kp, kd, t)) != 0) {
140 e = key_strerror(rc);
143 if ((e = ec_getinfo(&ei, ep.cstr)) != 0)
147 if (G_FROMEC(*g, *p, &ep.p)) {
148 e = "bad public point";
157 static const kgops kgec_ops = { "ec", kgec_priv, kgec_pub };
159 /* --- Table of supported key types --- */
161 static const kgops *kgtab[] = { &kgdh_ops, &kgec_ops, 0 };
163 /*----- Algswitch stuff ---------------------------------------------------*/
165 /* --- @algs_get@ --- *
167 * Arguments: @algswitch *a@ = where to put the algorithms
168 * @key_file *kf@ = key file (for some stupid reason)
169 * @key *k@ = key to inspect
171 * Returns: Null if OK, or an error message.
173 * Use: Extracts an algorithm choice from a key.
176 static const char *algs_get(algswitch *a, key_file *kf, key *k)
183 #define FAIL(msg) do { e = msg; goto done; } while (0)
185 if ((p = key_getattr(kf, k, "cipher")) == 0)
187 if ((a->c = gcipher_byname(p)) == 0)
188 FAIL("unknown-cipher");
190 if ((p = key_getattr(kf, k, "hash")) == 0)
192 if ((a->h = ghash_byname(p)) == 0)
193 FAIL("unknown-hash");
195 if ((p = key_getattr(kf, k, "mgf")) == 0) {
197 dstr_putf(&d, "%s-mgf", a->h->name);
200 if ((a->mgf = gcipher_byname(p)) == 0)
201 FAIL("unknown-mgf-cipher");
203 if ((p = key_getattr(kf, k, "mac")) != 0) {
206 if ((q = strchr(d.buf, '/')) != 0)
208 if ((a->m = gmac_byname(d.buf)) == 0)
211 a->tagsz = a->m->hashsz;
213 unsigned long n = strtoul(q, &q, 0);
214 if (*q) FAIL("bad-tag-length-string");
215 if (n%8 || n > ~(size_t)0) FAIL("bad-tag-length");
220 dstr_putf(&d, "%s-hmac", a->h->name);
221 if ((a->m = gmac_byname(d.buf)) == 0)
222 FAIL("no-hmac-for-hash");
223 a->tagsz = a->h->hashsz/2;
232 /* --- @algs_check@ --- *
234 * Arguments: @algswitch *a@ = a choice of algorithms
235 * @const group *g@ = the group we're working in
237 * Returns: Null if OK, or an error message.
239 * Use: Checks an algorithm choice for sensibleness. This also
240 * derives some useful information from the choices, and you
241 * must call this before committing the algorithm selection
242 * for use by @keyset@ functions.
245 static const char *algs_check(algswitch *a, const group *g)
247 /* --- Derive the key sizes --- *
249 * Must ensure that we have non-empty keys. This isn't ideal, but it
250 * provides a handy sanity check. Also must be based on a 64- or 128-bit
251 * block cipher or we can't do the data expiry properly.
254 a->hashsz = a->h->hashsz;
255 if ((a->cksz = keysz(a->hashsz, a->c->keysz)) == 0)
256 return ("no key size found for cipher");
257 if ((a->mksz = keysz(a->hashsz, a->m->keysz)) == 0)
258 return ("no key size found for MAC");
260 /* --- Derive the data limit --- */
262 if (a->c->blksz < 16) a->expsz = MEG(64);
263 else a->expsz = MEG(2048);
265 /* --- Ensure that the tag size is sane --- */
267 if (a->tagsz > a->m->hashsz) return ("tag length too large");
269 /* --- Ensure the MGF accepts hashes as keys --- */
271 if (keysz(a->hashsz, a->mgf->keysz) != a->hashsz)
272 return ("MGF not suitable -- restrictive key schedule");
274 /* --- All ship-shape and Bristol-fashion --- */
279 /* --- @algs_samep@ --- *
281 * Arguments: @const algswitch *a, *aa@ = two algorithm selections
283 * Returns: Nonzero if the two selections are the same.
285 * Use: Checks sameness of algorithm selections: used to ensure that
286 * peers are using sensible algorithms.
289 static int algs_samep(const algswitch *a, const algswitch *aa)
291 return (a->c == aa->c && a->mgf == aa->mgf && a->h == aa->h &&
292 a->m == aa->m && a->tagsz == aa->tagsz);
295 /*----- Main code ---------------------------------------------------------*/
297 /* --- @keymoan@ --- *
299 * Arguments: @const char *file@ = name of the file
300 * @int line@ = line number in file
301 * @const char *msg@ = error message
302 * @void *p@ = argument pointer
306 * Use: Reports an error message about loading a key file.
309 static void keymoan(const char *file, int line, const char *msg, void *p)
320 * Arguments: @key_file *kf@ = pointer to key file
321 * @key *k@ = pointer to key
322 * @const char **tyr@ = where to put the type string
324 * Returns: Pointer to indicated key-group options, or null.
326 * Use: Looks up a key's group indicator and tries to find a matching
330 static const kgops *keykg(key_file *kf, key *k, const char **tyr)
335 /* --- Look up the key type in the table --- *
337 * There are several places to look for this. The most obvious is the
338 * `kx-group' key attribute. But there's also the key type itself.
341 ty = key_getattr(kf, k, "kx-group");
342 if (!ty && strncmp(k->type, "tripe-", 6) == 0) ty = k->type + 6;
346 for (ko = kgtab; *ko; ko++) {
347 if (strcmp((*ko)->ty, ty) == 0)
353 /* --- @loadpriv@ --- *
355 * Arguments: @dstr *d@ = string to write errors in
357 * Returns: Zero if OK, nonzero on error.
359 * Use: Loads the private key from its keyfile.
362 static int loadpriv(dstr *d)
372 const char *e, *tag, *ty;
375 /* --- Open the private key file --- */
377 if (key_open(&kf, kr_priv, KOPEN_READ, keymoan, 0)) {
378 dstr_putf(d, "error reading private keyring `%s': %s",
379 kr_priv, strerror(errno));
383 /* --- Find the private key --- */
386 key_qtag(&kf, tag = tag_priv, &t, &k, &kd) :
387 key_qtag(&kf, tag = "tripe", &t, &k, &kd) &&
388 key_qtag(&kf, tag = "tripe-dh", &t, &k, &kd)) {
389 dstr_putf(d, "private key `%s' not found in keyring `%s'", tag, kr_priv);
393 /* --- Look up the key type in the table --- */
395 if ((ko = keykg(&kf, k, &ty)) == 0) {
396 dstr_putf(d, "private key `%s' has unknown type `%s'", t.buf, ty);
400 /* --- Load the key --- */
402 if ((e = ko->loadpriv(*kd, &g, &x, &t)) != 0) {
403 dstr_putf(d, "error reading private key `%s': %s", t.buf, e);
407 /* --- Check that the key is sensible --- */
409 if ((e = G_CHECK(g, &rand_global)) != 0) {
410 dstr_putf(d, "bad group in private key `%s': %s", t.buf, e);
414 /* --- Collect the algorithms --- */
416 if ((e = algs_get(&a, &kf, k)) != 0 ||
417 (e = algs_check(&a, g)) != 0) {
418 dstr_putf(d, "bad symmetric algorithm selection in private key `%s': %s",
423 /* --- Good, we're happy --- *
425 * Dodginess! We change the group over here, but don't free any old group
426 * elements. This assumes that the new group is basically the same as the
427 * old one, and will happily adopt the existing elements. If it isn't,
428 * then we lose badly. Check this, then.
432 if (!group_samep(g, gg)) {
433 dstr_putf(d, "private key `%s' has different group", t.buf);
444 G_EXP(g, kpub, g->g, x);
445 indexsz = mp_octets(g->r);
447 /* --- Dump out the group --- */
449 IF_TRACING(T_KEYMGMT, {
450 trace(T_KEYMGMT, "keymgmt: extracted private key `%s'", t.buf);
451 IF_TRACING(T_CRYPTO, {
452 trace(T_CRYPTO, "crypto: r = %s", mpstr(g->r));
453 trace(T_CRYPTO, "crypto: h = %s", mpstr(g->h));
454 trace(T_CRYPTO, "crypto: x = %s", mpstr(x));
455 trace(T_CRYPTO, "crypto: cipher = %s", a.c->name);
456 trace(T_CRYPTO, "crypto: mgf = %s", a.mgf->name);
457 trace(T_CRYPTO, "crypto: hash = %s", a.h->name);
458 trace(T_CRYPTO, "crypto: mac = %s/%lu",
459 a.m->name, (unsigned long)a.tagsz * 8);
463 /* --- Success! --- */
470 /* --- Tidy up --- */
477 if (g) G_DESTROYGROUP(g);
481 /* --- @loadpub@ --- *
483 * Arguments: @dstr *d@ = string to write errors to
485 * Returns: Zero if OK, nonzero on error.
487 * Use: Reloads the public keyring.
490 static int loadpub(dstr *d)
492 key_file *kf = CREATE(key_file);
494 if (key_open(kf, kr_pub, KOPEN_READ, keymoan, 0)) {
495 dstr_putf(d, "error reading public keyring `%s': %s",
496 kr_pub, strerror(errno));
501 T( trace(T_KEYMGMT, "keymgmt: loaded public keyring `%s'", kr_pub); )
505 /* --- @km_reload@ --- *
509 * Returns: Zero if OK, nonzero to force reloading of keys.
511 * Use: Checks the keyrings to see if they need reloading.
520 /* --- Check the private key first --- */
522 if (fwatch_update(&w_priv, kr_priv)) {
523 T( trace(T_KEYMGMT, "keymgmt: private keyring updated: reloading..."); )
526 a_warn("KEYMGMT", "bad-private-key", "%s", d.buf, A_END);
531 /* --- Now check the public keys --- */
533 if (fwatch_update(&w_pub, kr_pub)) {
534 T( trace(T_KEYMGMT, "keymgmt: public keyring updated: reloading..."); )
538 a_warn("KEYMGMT", "bad-public-keyring", "%s", d.buf, A_END);
551 /* --- @km_init@ --- *
553 * Arguments: @const char *priv@ = private keyring file
554 * @const char *pub@ = public keyring file
555 * @const char *tag@ = tag to load
559 * Use: Initializes, and loads the private key.
562 void km_init(const char *priv, const char *pub, const char *tag)
565 const gchash *const *hh;
570 fwatch_init(&w_priv, kr_priv);
571 fwatch_init(&w_pub, kr_pub);
573 for (hh = ghashtab; *hh; hh++) {
574 if ((*hh)->hashsz > MAXHASHSZ) {
575 die(EXIT_FAILURE, "INTERNAL ERROR: %s hash length %lu > MAXHASHSZ %d",
576 (*hh)->name, (unsigned long)(*hh)->hashsz, MAXHASHSZ);
582 die(EXIT_FAILURE, "%s", d.buf);
584 die(EXIT_FAILURE, "%s", d.buf);
587 /* --- @km_getpubkey@ --- *
589 * Arguments: @const char *tag@ = public key tag to load
590 * @ge *kpub@ = where to put the public key
591 * @time_t *t_exp@ = where to put the expiry time
593 * Returns: Zero if OK, nonzero if it failed.
595 * Use: Fetches a public key from the keyring.
598 int km_getpubkey(const char *tag, ge *kpub, time_t *t_exp)
610 /* --- Find the key --- */
612 if (key_qtag(kf_pub, tag, &t, &k, &kd)) {
613 a_warn("KEYMGMT", "public-key", "%s", tag, "not-found", A_END);
617 /* --- Look up the key type in the table --- */
619 if ((ko = keykg(kf_pub, k, &ty)) == 0) {
621 "public-key", "%s", t.buf,
622 "unknown-type", "%s", ty,
627 /* --- Load the key --- */
629 if ((e = ko->loadpub(*kd, &g, &p, &t)) != 0) {
630 a_warn("KEYMGMT", "public-key", "%s", t.buf, "bad", "%s", e, A_END);
634 /* --- Ensure that the group is correct --- *
636 * Dodginess! We assume that if this works, our global group is willing to
637 * adopt this public element. Probably reasonable.
640 if (!group_samep(gg, g)) {
641 a_warn("KEYMGMT", "public-key", "%s", t.buf, "incorrect-group", A_END);
645 /* --- Check the public group element --- */
647 if (group_check(gg, p)) {
649 "public-key", "%s", t.buf,
650 "bad-public-group-element",
655 /* --- Check the algorithms --- */
657 if ((e = algs_get(&a, kf_pub, k)) != 0) {
659 "public-key", "%s", t.buf,
660 "bad-algorithm-selection", e,
664 if (!algs_samep(&a, &algs)) {
666 "public-key", "%s", t.buf,
667 "algorithm-mismatch",
672 /* --- Dump the public key --- */
674 IF_TRACING(T_KEYMGMT, {
675 trace(T_KEYMGMT, "keymgmt: extracted public key `%s'", t.buf);
676 trace(T_CRYPTO, "crypto: p = %s", gestr(gg, p));
679 /* --- OK, accept the public key --- */
685 /* --- Tidy up --- */
688 if (p) G_DESTROY(g, p);
689 if (g) G_DESTROYGROUP(g);
694 /*----- That's all, folks -------------------------------------------------*/