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 /*----- Key groups --------------------------------------------------------*/
33 /* The key-loading functions here must fill in the kdata slot @g@ and
34 * either @kpriv@ or @kpub@ as appropriate. The caller will take care of
35 * determining @kpub@ given a private key, and of ensuring that @kpriv@ is
36 * null for a public key.
39 typedef struct kgops {
41 int (*loadpriv)(key_data *, kdata *, dstr *, dstr *);
42 int (*loadpub)(key_data *, kdata *, dstr *, dstr *);
45 /* --- Diffie-Hellman --- */
47 static int kgdh_priv(key_data *d, kdata *kd, dstr *t, dstr *e)
49 key_packstruct kps[DH_PRIVFETCHSZ];
54 kp = key_fetchinit(dh_privfetch, kps, &dp);
55 if ((rc = key_unpack(kp, d, t)) != 0) {
56 a_format(e, "unpack-failed", "%s", key_strerror(rc), A_END);
59 kd->g = group_prime(&dp.dp);
60 kd->kpriv = MP_COPY(dp.x);
70 static int kgdh_pub(key_data *d, kdata *kd, dstr *t, dstr *e)
72 key_packstruct kps[DH_PUBFETCHSZ];
77 kp = key_fetchinit(dh_pubfetch, kps, &dp);
78 if ((rc = key_unpack(kp, d, t)) != 0) {
79 a_format(e, "unpack-failed", "%s", key_strerror(rc), A_END);
82 kd->g = group_prime(&dp.dp);
83 kd->kpub = G_CREATE(kd->g);
84 if (G_FROMINT(kd->g, kd->kpub, dp.y)) {
85 a_format(e, "bad-public-vector", A_END);
91 G_DESTROY(kd->g, kd->kpub);
92 G_DESTROYGROUP(kd->g);
100 static const kgops kgdh_ops = { "dh", kgdh_priv, kgdh_pub };
102 /* --- Elliptic curve --- */
104 static int kgec_priv(key_data *d, kdata *kd, dstr *t, dstr *e)
106 key_packstruct kps[EC_PRIVFETCHSZ];
113 kp = key_fetchinit(ec_privfetch, kps, &ep);
114 if ((rc = key_unpack(kp, d, t)) != 0) {
115 a_format(e, "unpack-failed", "%s", key_strerror(rc), A_END);
118 if ((err = ec_getinfo(&ei, ep.cstr)) != 0) {
119 a_format(e, "decode-failed", "%s", err, A_END);
122 kd->g = group_ec(&ei);
123 kd->kpriv = MP_COPY(ep.x);
133 static int kgec_pub(key_data *d, kdata *kd, dstr *t, dstr *e)
135 key_packstruct kps[EC_PUBFETCHSZ];
142 kp = key_fetchinit(ec_pubfetch, kps, &ep);
143 if ((rc = key_unpack(kp, d, t)) != 0) {
144 a_format(e, "unpack-failed", "%s", key_strerror(rc), A_END);
147 if ((err = ec_getinfo(&ei, ep.cstr)) != 0) {
148 a_format(e, "decode-failed", "%s", err, A_END);
151 kd->g = group_ec(&ei);
152 kd->kpub = G_CREATE(kd->g);
153 if (G_FROMEC(kd->g, kd->kpub, &ep.p)) {
154 a_format(e, "bad-public-vector", A_END);
160 G_DESTROY(kd->g, kd->kpub);
161 G_DESTROYGROUP(kd->g);
169 static const kgops kgec_ops = { "ec", kgec_priv, kgec_pub };
171 /* --- Table of supported key types --- */
173 static const kgops *kgtab[] = { &kgdh_ops, &kgec_ops, 0 };
175 /*----- Algswitch stuff ---------------------------------------------------*/
177 /* --- @algs_get@ --- *
179 * Arguments: @algswitch *a@ = where to put the algorithms
180 * @dstr *e@ = where to write errror tokens
181 * @key_file *kf@ = key file
182 * @key *k@ = key to inspect
184 * Returns: Zero if OK; nonzero on error.
186 * Use: Extracts an algorithm choice from a key.
189 static int algs_get(algswitch *a, dstr *e, key_file *kf, key *k)
196 /* --- Symmetric encryption for bulk data --- */
198 if ((p = key_getattr(kf, k, "cipher")) == 0) p = "blowfish-cbc";
199 if ((a->c = gcipher_byname(p)) == 0) {
200 a_format(e, "unknown-cipher", "%s", p, A_END);
204 /* --- Hash function --- */
206 if ((p = key_getattr(kf, k, "hash")) == 0) p = "rmd160";
207 if ((a->h = ghash_byname(p)) == 0) {
208 a_format(e, "unknown-hash", "%s", p, A_END);
212 /* --- Symmetric encryption for key derivation --- */
214 if ((p = key_getattr(kf, k, "mgf")) == 0) {
216 dstr_putf(&d, "%s-mgf", a->h->name);
219 if ((a->mgf = gcipher_byname(p)) == 0) {
220 a_format(e, "unknown-mgf-cipher", "%s", p, A_END);
224 /* --- Message authentication for bulk data --- */
226 if ((p = key_getattr(kf, k, "mac")) != 0) {
229 if ((q = strchr(d.buf, '/')) != 0)
231 if ((a->m = gmac_byname(d.buf)) == 0) {
232 a_format(e, "unknown-mac", "%s", d.buf, A_END);
236 a->tagsz = a->m->hashsz;
238 unsigned long n = strtoul(q, &qq, 0);
240 a_format(e, "bad-tag-length-string", "%s", q, A_END);
243 if (n%8 || n/8 > a->m->hashsz) {
244 a_format(e, "bad-tag-length", "%lu", n, A_END);
251 dstr_putf(&d, "%s-hmac", a->h->name);
252 if ((a->m = gmac_byname(d.buf)) == 0) {
253 a_format(e, "no-hmac-for-hash", "%s", a->h->name, A_END);
256 a->tagsz = a->h->hashsz/2;
265 /* --- @algs_check@ --- *
267 * Arguments: @algswitch *a@ = a choice of algorithms
268 * @dstr *e@ = where to write error tokens
269 * @const group *g@ = the group we're working in
271 * Returns: Zero if OK; nonzero on error.
273 * Use: Checks an algorithm choice for sensibleness. This also
274 * derives some useful information from the choices, and you
275 * must call this before committing the algorithm selection
276 * for use by @keyset@ functions.
279 static int algs_check(algswitch *a, dstr *e, const group *g)
281 /* --- Derive the key sizes --- *
283 * Must ensure that we have non-empty keys. This isn't ideal, but it
284 * provides a handy sanity check. Also must be based on a 64- or 128-bit
285 * block cipher or we can't do the data expiry properly.
288 a->hashsz = a->h->hashsz;
289 if ((a->cksz = keysz(a->hashsz, a->c->keysz)) == 0) {
290 a_format(e, "cipher", "%s", a->c->name,
291 "no-key-size", "%lu", (unsigned long)a->hashsz,
295 if ((a->mksz = keysz(a->hashsz, a->m->keysz)) == 0) {
296 a_format(e, "mac", "%s", a->m->name,
297 "no-key-size", "%lu", (unsigned long)a->hashsz,
302 /* --- Derive the data limit --- */
304 if (a->c->blksz < 16) a->expsz = MEG(64);
305 else a->expsz = MEG(2048);
307 /* --- Ensure the MGF accepts hashes as keys --- */
309 if (keysz(a->hashsz, a->mgf->keysz) != a->hashsz) {
310 a_format(e, "mgf", "%s", a->mgf->name,
311 "restrictive-key-schedule",
316 /* --- All ship-shape and Bristol-fashion --- */
321 /* --- @km_samealgsp@ --- *
323 * Arguments: @const kdata *kdx, *kdy@ = two key data objects
325 * Returns: Nonzero if their two algorithm selections are the same.
327 * Use: Checks sameness of algorithm selections: used to ensure that
328 * peers are using sensible algorithms.
331 int km_samealgsp(const kdata *kdx, const kdata *kdy)
333 const algswitch *a = &kdx->algs, *aa = &kdy->algs;
335 return (group_samep(kdx->g, kdy->g) && a->c == aa->c &&
336 a->mgf == aa->mgf && a->h == aa->h &&
337 a->m == aa->m && a->tagsz == aa->tagsz);
340 /*----- Key data and key nodes --------------------------------------------*/
342 typedef struct keyhalf {
344 int (*load)(const kgops *, key_data *, kdata *, dstr *, dstr *);
351 /* --- @kh_loadpub@, @kh_loadpriv@ --- *
353 * Arguments: @const kgops *ko@ = key-group operations for key type
354 * @key_data *d@ = key data object as stored in keyring
355 * @kdata *kd@ = our key-data object to fill in
356 * @dstr *t@ = the key tag name
357 * @dstr *e@ = a string to write error tokens to
359 * Returns: Zero on success, @-1@ on error.
361 * Use: These functions handle the main difference between public and
362 * private key halves. They are responsible for setting @g@,
363 * @kpriv@ and @kpub@ appropriately in all keys, handling the
364 * mismatch between the largely half-indifferent calling code
365 * and the group-specific loading functions.
367 * The function @kh_loadpriv@ is also responsible for checking
368 * the group for goodness. We don't bother checking public
369 * keys, because each public key we actually end up using must
370 * share a group with a private key which we'll already have
374 static int kh_loadpub(const kgops *ko, key_data *d, kdata *kd,
379 if ((rc = ko->loadpub(d, kd, t, e)) != 0)
381 if (group_check(kd->g, kd->kpub)) {
382 a_format(e, "bad-public-group-element");
389 G_DESTROY(kd->g, kd->kpub);
390 G_DESTROYGROUP(kd->g);
395 static int kh_loadpriv(const kgops *ko, key_data *d, kdata *kd,
401 if ((rc = ko->loadpriv(d, kd, t, e)) != 0)
403 if ((err = G_CHECK(kd->g, &rand_global)) != 0) {
404 a_format(e, "bad-group", "%s", err, A_END);
407 kd->kpub = G_CREATE(kd->g);
408 G_EXP(kd->g, kd->kpub, kd->g->g, kd->kpriv);
413 G_DESTROYGROUP(kd->g);
418 static struct keyhalf
419 priv = { "private", kh_loadpriv },
420 pub = { "public", kh_loadpub };
422 /* --- @keymoan@ --- *
424 * Arguments: @const char *file@ = name of the file
425 * @int line@ = line number in file
426 * @const char *msg@ = error message
427 * @void *p@ = argument pointer (indicates which keyring)
431 * Use: Reports an error message about loading a key file.
434 static void keymoan(const char *file, int line, const char *msg, void *p)
439 a_warn("KEYMGMT", "%s-keyring", kh->kind, "%s", file,
440 "io-error", "?ERRNO", A_END);
442 a_warn("KEYMGMT", "%s-keyring", kh->kind, "%s", file, "line", "%d", line,
447 /* --- @kh_reopen@ --- *
449 * Arguments: @keyhalf *kh@ = pointer to keyhalf structure
451 * Returns: Zero on success, @-1@ on error.
453 * Use: Reopens the key file for the appropriate key half. If this
454 * fails, everything is left as it was; if it succeeds, then the
455 * old file is closed (if it was non-null) and the new one put
459 static int kh_reopen(keyhalf *kh)
461 key_file *kf = CREATE(key_file);
463 if (key_open(kf, kh->kr, KOPEN_READ, keymoan, kh)) {
464 a_warn("KEYMGMT", "%s-keyring", kh->kind, "%s", kh->kr,
465 "io-error", "?ERRNO", A_END);
478 /* --- @kh_init@ --- *
480 * Arguments: @keyhalf *kh@ = pointer to keyhalf structure to set up
481 * @const char *kr@ = name of the keyring file
485 * Use: Initialize a keyhalf structure, maintaining the private or
486 * public keys. Intended to be called during initialization:
487 * exits if there's some kind of problem.
490 static void kh_init(keyhalf *kh, const char *kr)
493 fwatch_init(&kh->w, kr);
494 sym_create(&kh->tab);
498 die(EXIT_FAILURE, "failed to load %s keyring `%s'", kh->kind, kr);
501 /* --- @kh_load@ --- *
503 * Arguments: @keyhalf *kh@ = pointer to keyhalf
504 * @const char *tag@ = key tag to be loaded
505 * @int complainp@ = whether to complain about missing keys
507 * Returns: Pointer to a @kdata@ structure if successful, or null on
510 * Use: Attempts to load a key from the current key file. This
511 * function always reads data from the file: it's used when
512 * there's a cache miss from @kh_find@, and when refreshing the
513 * known keys in @kh_refresh@. The returned kdata has a
514 * reference count of exactly 1, and has no home knode.
517 static kdata *kh_load(keyhalf *kh, const char *tag, int complainp)
527 /* --- Find the key and grab its tag --- */
529 if (key_qtag(kh->kf, tag, &t, &k, &d)) {
531 a_warn("KEYMGMT", "%s-keyring", kh->kind, "%s", kh->kr,
532 "key-not-found", "%s", tag, A_END);
537 /* --- Find the key's group type and the appropriate operations --- *
539 * There are several places to look for the key type. The most obvious is
540 * the `kx-group' key attribute. But there's also the key type itself, for
541 * compatibility reasons.
544 ty = key_getattr(kh->kf, k, "kx-group");
545 if (!ty && strncmp(k->type, "tripe-", 6) == 0) ty = k->type + 6;
548 for (ko = kgtab; *ko; ko++)
549 if (strcmp((*ko)->ty, ty) == 0) goto foundko;
550 a_warn("KEYMGMT", "%s-keyring", kh->kind,
551 "%s", kh->kr, "key", "%s", t.buf,
552 "unknown-group-type", "%s", ty, A_END);
557 if (kh->load(*ko, *d, kd, &t, &e)) {
558 a_warn("KEYMGMT", "%s-keyring", kh->kind,
559 "%s", kh->kr, "key" "%s", t.buf,
560 "*%s", e.buf, A_END);
564 if (algs_get(&kd->algs, &e, kh->kf, k) ||
565 (kd->kpriv && algs_check(&kd->algs, &e, kd->g))) {
566 a_warn("KEYMGMT", "%s-keyring", kh->kind,
567 "%s", kh->kr, "key", "%s", t.buf,
568 "*%s", e.buf, A_END);
572 kd->tag = xstrdup(t.buf);
573 kd->indexsz = mp_octets(kd->g->r);
578 IF_TRACING(T_KEYMGMT, {
579 trace(T_KEYMGMT, "keymgmt: loaded %s key `%s'", kh->kind, t.buf);
580 IF_TRACING(T_CRYPTO, {
581 trace(T_CRYPTO, "crypto: r = %s", mpstr(kd->g->r));
582 trace(T_CRYPTO, "crypto: h = %s", mpstr(kd->g->h));
584 trace(T_CRYPTO, "crypto: x = %s", mpstr(kd->kpriv));
585 trace(T_CRYPTO, "crypto: cipher = %s", kd->algs.c->name);
586 trace(T_CRYPTO, "crypto: mgf = %s", kd->algs.mgf->name);
587 trace(T_CRYPTO, "crypto: hash = %s", kd->algs.h->name);
588 trace(T_CRYPTO, "crypto: mac = %s/%lu",
589 kd->algs.m->name, (unsigned long)kd->algs.tagsz * 8);
596 if (kd->kpriv) mp_drop(kd->kpriv);
597 G_DESTROY(kd->g, kd->kpub);
598 G_DESTROYGROUP(kd->g);
609 /* --- @kh_find@ --- *
611 * Arguments: @keyhalf *kh@ = pointer to the keyhalf
612 * @const char *tag@ = key to be obtained
613 * @int complainp@ = whether to complain about missing keys
615 * Returns: A pointer to the kdata, or null on error.
617 * Use: Obtains kdata, maybe from the cache. This won't update a
618 * stale cache entry, though @kh_refresh@ ought to have done
619 * that already. The returned kdata object may be shared with
620 * other users. (One of this function's responsibilities, over
621 * @kh_load@, is to set the home knode of a freshly loaded
625 static kdata *kh_find(keyhalf *kh, const char *tag, int complainp)
631 kn = sym_find(&kh->tab, tag, -1, sizeof(knode), &f);
634 if (kn->f & KNF_BROKEN) {
636 trace(T_KEYMGMT, "keymgmt: key `%s' marked as broken", tag); )
642 T( trace(T_KEYMGMT, "keymgmt: %scache hit for key `%s'",
643 kd ? "" : "negative ", tag); )
646 kd = kh_load(kh, tag, complainp);
660 /* --- @kh_refresh@ --- *
662 * Arguments: @keyhalf *kh@ = pointer to the keyhalf
664 * Returns: Zero if nothing needs to be done; nonzero if peers should
665 * refresh their keys.
667 * Use: Refreshes cached keys from files.
669 * Each active knode is examined to see if a new key is
670 * available: the return value is nonzero if any new keys are.
671 * A key is considered new if its algorithms, public key, or
672 * expiry time are/is different.
674 * Stub knodes (with no kdata attached) are removed, so that a
675 * later retry can succeed if the file has been fixed. (This
676 * doesn't count as a change, since no peers should be relying
677 * on a nonexistent key.)
680 static int kh_refresh(keyhalf *kh)
687 if (!fwatch_update(&kh->w, kh->kr) || kh_reopen(kh))
690 T( trace(T_KEYMGMT, "keymgmt: rescan %s keyring `%s'", kh->kind, kh->kr); )
691 for (sym_mkiter(&i, &kh->tab); (kn = sym_next(&i)) != 0; ) {
693 T( trace(T_KEYMGMT, "keymgmt: discard stub entry for key `%s'",
695 sym_remove(&kh->tab, kn);
698 if ((kd = kh_load(kh, SYM_NAME(kn), 1)) == 0) {
699 if (!(kn->f & KNF_BROKEN)) {
700 T( trace(T_KEYMGMT, "keymgmt: failed to load new key `%s': "
701 "marking it as broken",
707 kn->f &= ~KNF_BROKEN;
708 if (kd->t_exp == kn->kd->t_exp &&
709 km_samealgsp(kd, kn->kd) &&
710 G_EQ(kd->g, kd->kpub, kn->kd->kpub)) {
711 T( trace(T_KEYMGMT, "keymgmt: key `%s' unchanged", SYM_NAME(kn)); )
714 T( trace(T_KEYMGMT, "keymgmt: loaded new version of key `%s'",
725 /*----- Main code ---------------------------------------------------------*/
727 const char *tag_priv;
730 /* --- @km_init@ --- *
732 * Arguments: @const char *privkr@ = private keyring file
733 * @const char *pubkr@ = public keyring file
734 * @const char *ptag@ = default private-key tag
738 * Use: Initializes the key-management machinery, loading the
739 * keyrings and so on.
742 void km_init(const char *privkr, const char *pubkr, const char *ptag)
744 const gchash *const *hh;
746 for (hh = ghashtab; *hh; hh++) {
747 if ((*hh)->hashsz > MAXHASHSZ) {
748 die(EXIT_FAILURE, "INTERNAL ERROR: %s hash length %lu > MAXHASHSZ %d",
749 (*hh)->name, (unsigned long)(*hh)->hashsz, MAXHASHSZ);
753 kh_init(&priv, privkr);
754 kh_init(&pub, pubkr);
757 if ((master = km_findpriv(ptag)) == 0) exit(EXIT_FAILURE);
760 /* --- @km_reload@ --- *
764 * Returns: Zero if OK, nonzero to force reloading of keys.
766 * Use: Checks the keyrings to see if they need reloading.
774 if (kh_refresh(&priv)) {
783 if (kh_refresh(&pub))
788 /* --- @km_findpub@, @km_findpriv@ --- *
790 * Arguments: @const char *tag@ = key tag to load
792 * Returns: Pointer to the kdata object if successful, or null on error.
794 * Use: Fetches a public or private key from the keyring.
797 kdata *km_findpub(const char *tag) { return (kh_find(&pub, tag, 1)); }
799 kdata *km_findpriv(const char *tag)
803 /* Unpleasantness for the sake of compatibility. */
804 if (!tag && (kd = kh_find(&priv, "tripe", 0)) != 0) return (kd);
805 else return (kh_find(&priv, tag ? tag : "tripe-dh", 1));
808 /* --- @km_tag@ --- *
810 * Arguments: @kdata *kd@ - pointer to the kdata object
812 * Returns: A pointer to the short tag by which the kdata was loaded.
815 const char *km_tag(kdata *kd) { return (SYM_NAME(kd->kn)); }
817 /* --- @km_ref@ --- *
819 * Arguments: @kdata *kd@ = pointer to the kdata object
823 * Use: Claim a new reference to a kdata object.
826 void km_ref(kdata *kd) { kd->ref++; }
828 /* --- @km_unref@ --- *
830 * Arguments: @kdata *kd@ = pointer to the kdata object
834 * Use: Releases a reference to a kdata object.
837 void km_unref(kdata *kd)
839 if (--kd->ref) return;
840 if (kd->kpriv) mp_drop(kd->kpriv);
841 G_DESTROY(kd->g, kd->kpub);
843 G_DESTROYGROUP(kd->g);
846 /*----- That's all, folks -------------------------------------------------*/