5 * Key loading and storing
7 * (c) 2001 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Trivial IP Encryption (TrIPE).
14 * TrIPE is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * TrIPE is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with TrIPE; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Header files ------------------------------------------------------*/
33 /*----- Global variables --------------------------------------------------*/
40 /*----- Static variables --------------------------------------------------*/
42 static key_file
*kf_pub
;
43 static const char *kr_priv
, *kr_pub
, *tag_priv
;
44 static fwatch w_priv
, w_pub
;
46 /*----- Key groups --------------------------------------------------------*/
48 typedef struct kgops
{
50 const char *(*loadpriv
)(key_data
*, group
**, mp
**, dstr
*);
51 const char *(*loadpub
)(key_data
*, group
**, ge
**, dstr
*);
54 /* --- Diffie-Hellman --- */
56 static const char *kgdh_priv(key_data
*kd
, group
**g
, mp
**x
, dstr
*t
)
58 key_packstruct kps
[DH_PRIVFETCHSZ
];
64 kp
= key_fetchinit(dh_privfetch
, kps
, &dp
);
65 if ((rc
= key_unpack(kp
, kd
, t
)) != 0) {
69 *g
= group_prime(&dp
.dp
);
77 static const char *kgdh_pub(key_data
*kd
, group
**g
, ge
**p
, dstr
*t
)
79 key_packstruct kps
[DH_PUBFETCHSZ
];
85 kp
= key_fetchinit(dh_pubfetch
, kps
, &dp
);
86 if ((rc
= key_unpack(kp
, kd
, t
)) != 0) {
90 *g
= group_prime(&dp
.dp
);
92 if (G_FROMINT(*g
, *p
, dp
.y
)) {
93 e
= "bad public value";
102 static const kgops kgdh_ops
= { "tripe-dh", kgdh_priv
, kgdh_pub
};
104 /* --- Elliptic curve --- */
106 static const char *kgec_priv(key_data
*kd
, group
**g
, mp
**x
, dstr
*t
)
108 key_packstruct kps
[EC_PRIVFETCHSZ
];
115 kp
= key_fetchinit(ec_privfetch
, kps
, &ep
);
116 if ((rc
= key_unpack(kp
, kd
, t
)) != 0) {
117 e
= key_strerror(rc
);
120 if ((e
= ec_getinfo(&ei
, ep
.cstr
)) != 0)
130 static const char *kgec_pub(key_data
*kd
, group
**g
, ge
**p
, dstr
*t
)
132 key_packstruct kps
[EC_PUBFETCHSZ
];
139 kp
= key_fetchinit(ec_pubfetch
, kps
, &ep
);
140 if ((rc
= key_unpack(kp
, kd
, t
)) != 0) {
141 e
= key_strerror(rc
);
144 if ((e
= ec_getinfo(&ei
, ep
.cstr
)) != 0)
148 if (G_FROMEC(*g
, *p
, &ep
.p
)) {
149 e
= "bad public point";
158 static const kgops kgec_ops
= { "tripe-ec", kgec_priv
, kgec_pub
};
160 /* --- Table of supported key types --- */
162 static const kgops
*kgtab
[] = { &kgdh_ops
, &kgec_ops
, 0 };
164 /*----- Algswitch stuff ---------------------------------------------------*/
166 /* --- @algs_get@ --- *
168 * Arguments: @algswitch *a@ = where to put the algorithms
169 * @key_file *kf@ = key file (for some stupid reason)
170 * @key *k@ = key to inspect
172 * Returns: Null if OK, or an error message.
174 * Use: Extracts an algorithm choice from a key.
177 static const char *algs_get(algswitch
*a
, key_file
*kf
, key
*k
)
184 #define FAIL(msg) do { e = msg; goto done; } while (0)
186 if ((p
= key_getattr(kf
, k
, "cipher")) == 0)
188 if ((a
->c
= gcipher_byname(p
)) == 0)
189 FAIL("unknown-cipher");
191 if ((p
= key_getattr(kf
, k
, "hash")) == 0)
193 if ((a
->h
= ghash_byname(p
)) == 0)
194 FAIL("unknown-hash");
196 if ((p
= key_getattr(kf
, k
, "mgf")) == 0) {
198 dstr_putf(&d
, "%s-mgf", a
->h
->name
);
201 if ((a
->mgf
= gcipher_byname(p
)) == 0)
202 FAIL("unknown-mgf-cipher");
204 if ((p
= key_getattr(kf
, k
, "mac")) != 0) {
207 if ((q
= strchr(d
.buf
, '/')) != 0)
209 if ((a
->m
= gmac_byname(d
.buf
)) == 0)
212 a
->tagsz
= a
->m
->hashsz
;
214 unsigned long n
= strtoul(q
, &q
, 0);
215 if (*q
) FAIL("bad-tag-length-string");
216 if (n
%8 || n
> ~(size_t)0) FAIL("bad-tag-length");
221 dstr_putf(&d
, "%s-hmac", a
->h
->name
);
222 if ((a
->m
= gmac_byname(d
.buf
)) == 0)
223 FAIL("no-hmac-for-hash");
224 a
->tagsz
= a
->h
->hashsz
/2;
233 /* --- @algs_check@ --- *
235 * Arguments: @algswitch *a@ = a choice of algorithms
236 * @const group *g@ = the group we're working in
238 * Returns: Null if OK, or an error message.
240 * Use: Checks an algorithm choice for sensibleness. This also
241 * derives some useful information from the choices, and you
242 * must call this before committing the algorithm selection
243 * for use by @keyset@ functions.
246 static const char *algs_check(algswitch
*a
, const group
*g
)
248 /* --- Derive the key sizes --- *
250 * Must ensure that we have non-empty keys. This isn't ideal, but it
251 * provides a handy sanity check.
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 /* --- Ensure that the tag size is sane --- */
262 if (a
->tagsz
> a
->m
->hashsz
) return ("tag length too large");
264 /* --- Ensure the MGF accepts hashes as keys --- */
266 if (keysz(a
->hashsz
, a
->mgf
->keysz
) != a
->hashsz
)
267 return ("MGF not suitable -- restrictive key schedule");
269 /* --- All ship-shape and Bristol-fashion --- */
274 /* --- @algs_samep@ --- *
276 * Arguments: @const algswitch *a, *aa@ = two algorithm selections
278 * Returns: Nonzero if the two selections are the same.
280 * Use: Checks sameness of algorithm selections: used to ensure that
281 * peers are using sensible algorithms.
284 static int algs_samep(const algswitch
*a
, const algswitch
*aa
)
286 return (a
->c
== aa
->c
&& a
->mgf
== aa
->mgf
&& a
->h
== aa
->h
&&
287 a
->m
== aa
->m
&& a
->tagsz
== aa
->tagsz
);
290 /*----- Main code ---------------------------------------------------------*/
292 /* --- @keymoan@ --- *
294 * Arguments: @const char *file@ = name of the file
295 * @int line@ = line number in file
296 * @const char *msg@ = error message
297 * @void *p@ = argument pointer
301 * Use: Reports an error message about loading a key file.
304 static void keymoan(const char *file
, int line
, const char *msg
, void *p
)
313 /* --- @loadpriv@ --- *
315 * Arguments: @dstr *d@ = string to write errors in
317 * Returns: Zero if OK, nonzero on error.
319 * Use: Loads the private key from its keyfile.
322 static int loadpriv(dstr
*d
)
335 /* --- Open the private key file --- */
337 if (key_open(&kf
, kr_priv
, KOPEN_READ
, keymoan
, 0)) {
338 dstr_putf(d
, "error reading private keyring `%s': %s",
339 kr_priv
, strerror(errno
));
343 /* --- Find the private key --- */
345 if (key_qtag(&kf
, tag_priv
, &t
, &k
, &kd
)) {
346 dstr_putf(d
, "private key `%s' not found in keyring `%s'",
351 /* --- Look up the key type in the table --- */
353 for (ko
= kgtab
; *ko
; ko
++) {
354 if (strcmp((*ko
)->ty
, k
->type
) == 0)
357 dstr_putf(d
, "private key `%s' has unknown type `%s'", t
.buf
, k
->type
);
361 /* --- Load the key --- */
363 if ((e
= (*ko
)->loadpriv(*kd
, &g
, &x
, &t
)) != 0) {
364 dstr_putf(d
, "error reading private key `%s': %s", t
.buf
, e
);
368 /* --- Check that the key is sensible --- */
370 if ((e
= G_CHECK(g
, &rand_global
)) != 0) {
371 dstr_putf(d
, "bad group in private key `%s': %s", t
.buf
, e
);
375 /* --- Collect the algorithms --- */
377 if ((e
= algs_get(&a
, &kf
, k
)) != 0 ||
378 (e
= algs_check(&a
, g
)) != 0) {
379 dstr_putf(d
, "bad symmetric algorithm selection in private key `%s': %s",
384 /* --- Good, we're happy --- *
386 * Dodginess! We change the group over here, but don't free any old group
387 * elements. This assumes that the new group is basically the same as the
388 * old one, and will happily adopt the existing elements. If it isn't,
389 * then we lose badly. Check this, then.
393 if (!group_samep(g
, gg
)) {
394 dstr_putf(d
, "private key `%s' has different group", t
.buf
);
405 G_EXP(g
, kpub
, g
->g
, x
);
407 /* --- Dump out the group --- */
409 IF_TRACING(T_KEYMGMT
, {
410 trace(T_KEYMGMT
, "keymgmt: extracted private key `%s'", t
.buf
);
411 IF_TRACING(T_CRYPTO
, {
412 trace(T_CRYPTO
, "crypto: r = %s", mpstr(g
->r
));
413 trace(T_CRYPTO
, "crypto: h = %s", mpstr(g
->h
));
414 trace(T_CRYPTO
, "crypto: x = %s", mpstr(x
));
415 trace(T_CRYPTO
, "crypto: cipher = %s", a
.c
->name
);
416 trace(T_CRYPTO
, "crypto: mgf = %s", a
.mgf
->name
);
417 trace(T_CRYPTO
, "crypto: hash = %s", a
.h
->name
);
418 trace(T_CRYPTO
, "crypto: mac = %s/%lu",
419 a
.m
->name
, (unsigned long)a
.tagsz
* 8);
423 /* --- Success! --- */
430 /* --- Tidy up --- */
437 if (g
) G_DESTROYGROUP(g
);
441 /* --- @loadpub@ --- *
443 * Arguments: @dstr *d@ = string to write errors to
445 * Returns: Zero if OK, nonzero on error.
447 * Use: Reloads the public keyring.
450 static int loadpub(dstr
*d
)
452 key_file
*kf
= CREATE(key_file
);
454 if (key_open(kf
, kr_pub
, KOPEN_READ
, keymoan
, 0)) {
455 dstr_putf(d
, "error reading public keyring `%s': %s",
456 kr_pub
, strerror(errno
));
461 T( trace(T_KEYMGMT
, "keymgmt: loaded public keyring `%s'", kr_pub
); )
465 /* --- @km_reload@ --- *
469 * Returns: Zero if OK, nonzero to force reloading of keys.
471 * Use: Checks the keyrings to see if they need reloading.
480 /* --- Check the private key first --- */
482 if (fwatch_update(&w_priv
, kr_priv
)) {
483 T( trace(T_KEYMGMT
, "keymgmt: private keyring updated: reloading..."); )
486 a_warn("KEYMGMT", "bad-private-key", "%s", d
.buf
, A_END
);
491 /* --- Now check the public keys --- */
493 if (fwatch_update(&w_pub
, kr_pub
)) {
494 T( trace(T_KEYMGMT
, "keymgmt: public keyring updated: reloading..."); )
498 a_warn("KEYMGMT", "bad-public-keyring", "%s", d
.buf
, A_END
);
511 /* --- @km_init@ --- *
513 * Arguments: @const char *priv@ = private keyring file
514 * @const char *pub@ = public keyring file
515 * @const char *tag@ = tag to load
519 * Use: Initializes, and loads the private key.
522 void km_init(const char *priv
, const char *pub
, const char *tag
)
525 const gchash
*const *hh
;
530 fwatch_init(&w_priv
, kr_priv
);
531 fwatch_init(&w_pub
, kr_pub
);
533 for (hh
= ghashtab
; *hh
; hh
++) {
534 if ((*hh
)->hashsz
> MAXHASHSZ
) {
535 die(EXIT_FAILURE
, "INTERNAL ERROR: %s hash length %lu > MAXHASHSZ %d",
536 (*hh
)->name
, (unsigned long)(*hh
)->hashsz
, MAXHASHSZ
);
542 die(EXIT_FAILURE
, "%s", d
.buf
);
544 die(EXIT_FAILURE
, "%s", d
.buf
);
547 /* --- @km_getpubkey@ --- *
549 * Arguments: @const char *tag@ = public key tag to load
550 * @ge *kpub@ = where to put the public key
551 * @time_t *t_exp@ = where to put the expiry time
553 * Returns: Zero if OK, nonzero if it failed.
555 * Use: Fetches a public key from the keyring.
558 int km_getpubkey(const char *tag
, ge
*kpub
, time_t *t_exp
)
570 /* --- Find the key --- */
572 if (key_qtag(kf_pub
, tag
, &t
, &k
, &kd
)) {
573 a_warn("KEYMGMT", "public-key", "%s", tag
, "not-found", A_END
);
577 /* --- Look up the key type in the table --- */
579 for (ko
= kgtab
; *ko
; ko
++) {
580 if (strcmp((*ko
)->ty
, k
->type
) == 0)
584 "public-key", "%s", t
.buf
,
585 "unknown-type", "%s", k
->type
,
590 /* --- Load the key --- */
592 if ((e
= (*ko
)->loadpub(*kd
, &g
, &p
, &t
)) != 0) {
593 a_warn("KEYMGMT", "public-key", "%s", t
.buf
, "bad", "%s", e
, A_END
);
597 /* --- Ensure that the group is correct --- *
599 * Dodginess! We assume that if this works, our global group is willing to
600 * adopt this public element. Probably reasonable.
603 if (!group_samep(gg
, g
)) {
604 a_warn("KEYMGMT", "public-key", "%s", t
.buf
, "incorrect-group", A_END
);
608 /* --- Check the public group element --- */
610 if (group_check(gg
, p
)) {
612 "public-key", "%s", t
.buf
,
613 "bad-public-group-element",
618 /* --- Check the algorithms --- */
620 if ((e
= algs_get(&a
, kf_pub
, k
)) != 0) {
622 "public-key", "%s", t
.buf
,
623 "bad-algorithm-selection", e
,
627 if (!algs_samep(&a
, &algs
)) {
629 "public-key", "%s", t
.buf
,
630 "algorithm-mismatch",
635 /* --- Dump the public key --- */
637 IF_TRACING(T_KEYMGMT
, {
638 trace(T_KEYMGMT
, "keymgmt: extracted public key `%s'", t
.buf
);
639 trace(T_CRYPTO
, "crypto: p = %s", gestr(gg
, p
));
642 /* --- OK, accept the public key --- */
648 /* --- Tidy up --- */
651 if (p
) G_DESTROY(g
, p
);
652 if (g
) G_DESTROYGROUP(g
);
657 /*----- That's all, folks -------------------------------------------------*/