5 * Catcrypt key-encapsulation
7 * (c) 2004 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb 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 Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Header files ------------------------------------------------------*/
34 #include <mLib/alloc.h>
35 #include <mLib/dstr.h>
36 #include <mLib/report.h>
48 #include "blowfish-cbc.h"
52 /*----- Key encapsulation -------------------------------------------------*/
56 typedef struct rsa_encctx
{
61 static kem
*rsa_encinit(key
*k
, void *kd
)
63 rsa_encctx
*re
= CREATE(rsa_encctx
);
64 rsa_pubcreate(&re
->rp
, kd
);
68 static int rsa_encdoit(kem
*k
, dstr
*d
, ghash
*h
)
70 rsa_encctx
*re
= (rsa_encctx
*)k
;
71 mp
*x
= mprand_range(MP_NEW
, re
->rp
.rp
->n
, &rand_global
, 0);
72 mp
*y
= rsa_pubop(&re
->rp
, MP_NEW
, x
);
73 size_t n
= mp_octets(re
->rp
.rp
->n
);
75 mp_storeb(x
, d
->buf
, n
);
76 GH_HASH(h
, d
->buf
, n
);
77 mp_storeb(y
, d
->buf
, n
);
84 static const char *rsa_lengthcheck(mp
*n
)
86 if (mp_bits(n
) < 1020) return ("key too short");
90 static const char *rsa_enccheck(kem
*k
)
92 rsa_encctx
*re
= (rsa_encctx
*)k
;
94 if ((e
= rsa_lengthcheck(re
->rp
.rp
->n
)) != 0) return (e
);
98 static void rsa_encdestroy(kem
*k
)
100 rsa_encctx
*re
= (rsa_encctx
*)k
;
101 rsa_pubdestroy(&re
->rp
);
105 static const kemops rsa_encops
= {
106 rsa_pubfetch
, sizeof(rsa_pub
),
107 rsa_encinit
, rsa_encdoit
, rsa_enccheck
, rsa_encdestroy
110 typedef struct rsa_decctx
{
115 static kem
*rsa_decinit(key
*k
, void *kd
)
117 rsa_decctx
*rd
= CREATE(rsa_decctx
);
118 rsa_privcreate(&rd
->rp
, kd
, &rand_global
);
122 static int rsa_decdoit(kem
*k
, dstr
*d
, ghash
*h
)
124 rsa_decctx
*rd
= (rsa_decctx
*)k
;
125 mp
*x
= mp_loadb(MP_NEW
, d
->buf
, d
->len
);
129 if (MP_CMP(x
, >=, rd
->rp
.rp
->n
)) {
133 n
= mp_octets(rd
->rp
.rp
->n
);
135 x
= rsa_privop(&rd
->rp
, x
, x
);
143 static const char *rsa_deccheck(kem
*k
)
145 rsa_decctx
*rd
= (rsa_decctx
*)k
;
147 if ((e
= rsa_lengthcheck(rd
->rp
.rp
->n
)) != 0) return (e
);
151 static void rsa_decdestroy(kem
*k
)
153 rsa_decctx
*rd
= (rsa_decctx
*)k
;
154 rsa_privdestroy(&rd
->rp
);
158 static const kemops rsa_decops
= {
159 rsa_privfetch
, sizeof(rsa_priv
),
160 rsa_decinit
, rsa_decdoit
, rsa_deccheck
, rsa_decdestroy
163 /* --- DH and EC --- */
165 typedef struct dh_encctx
{
172 static dh_encctx
*dh_doinit(key
*k
, const gprime_param
*gp
, mp
*y
,
173 group
*(*makegroup
)(const gprime_param
*),
176 dh_encctx
*de
= CREATE(dh_encctx
);
180 if ((de
->g
= makegroup(gp
)) == 0)
181 die(EXIT_FAILURE
, "bad %s group in key `%s'", what
, t
.buf
);
183 de
->y
= G_CREATE(de
->g
);
184 if (G_FROMINT(de
->g
, de
->y
, y
))
185 die(EXIT_FAILURE
, "bad public key `%s'", t
.buf
);
190 static dh_encctx
*ec_doinit(key
*k
, const char *cstr
, const ec
*y
)
192 dh_encctx
*de
= CREATE(dh_encctx
);
198 if ((e
= ec_getinfo(&ei
, cstr
)) != 0 ||
199 (de
->g
= group_ec(&ei
)) == 0)
200 die(EXIT_FAILURE
, "bad elliptic curve spec in key `%s': %s", t
.buf
, e
);
202 de
->y
= G_CREATE(de
->g
);
203 if (G_FROMEC(de
->g
, de
->y
, y
))
204 die(EXIT_FAILURE
, "bad public curve point `%s'", t
.buf
);
209 static kem
*dh_encinit(key
*k
, void *kd
)
212 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
, group_prime
, "prime");
216 static kem
*bindh_encinit(key
*k
, void *kd
)
219 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
, group_binary
, "binary");
223 static kem
*ec_encinit(key
*k
, void *kd
)
226 dh_encctx
*de
= ec_doinit(k
, ep
->cstr
, &ep
->p
);
230 static int dh_encdoit(kem
*k
, dstr
*d
, ghash
*h
)
232 dh_encctx
*de
= (dh_encctx
*)k
;
233 mp
*r
= mprand_range(MP_NEW
, de
->g
->r
, &rand_global
, 0);
234 ge
*x
= G_CREATE(de
->g
);
235 ge
*y
= G_CREATE(de
->g
);
236 size_t n
= de
->g
->noctets
;
239 G_EXP(de
->g
, x
, de
->g
->g
, r
);
240 G_EXP(de
->g
, y
, de
->y
, r
);
242 buf_init(&b
, d
->buf
, n
);
243 G_TORAW(de
->g
, &b
, y
);
244 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
245 buf_init(&b
, d
->buf
, n
);
246 G_TORAW(de
->g
, &b
, x
);
247 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
255 static const char *dh_enccheck(kem
*k
)
257 dh_encctx
*de
= (dh_encctx
*)k
;
259 if ((e
= G_CHECK(de
->g
, &rand_global
)) != 0)
261 if (group_check(de
->g
, de
->y
))
262 return ("public key not in subgroup");
266 static void dh_encdestroy(kem
*k
)
268 dh_encctx
*de
= (dh_encctx
*)k
;
269 G_DESTROY(de
->g
, de
->y
);
271 G_DESTROYGROUP(de
->g
);
274 static const kemops dh_encops
= {
275 dh_pubfetch
, sizeof(dh_pub
),
276 dh_encinit
, dh_encdoit
, dh_enccheck
, dh_encdestroy
279 static const kemops bindh_encops
= {
280 dh_pubfetch
, sizeof(dh_pub
),
281 bindh_encinit
, dh_encdoit
, dh_enccheck
, dh_encdestroy
284 static const kemops ec_encops
= {
285 ec_pubfetch
, sizeof(ec_pub
),
286 ec_encinit
, dh_encdoit
, dh_enccheck
, dh_encdestroy
289 static kem
*dh_decinit(key
*k
, void *kd
)
292 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
, group_prime
, "prime");
293 de
->x
= MP_COPY(dp
->x
);
297 static kem
*bindh_decinit(key
*k
, void *kd
)
300 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
, group_binary
, "binary");
301 de
->x
= MP_COPY(dp
->x
);
305 static kem
*ec_decinit(key
*k
, void *kd
)
308 dh_encctx
*de
= ec_doinit(k
, ep
->cstr
, &ep
->p
);
309 de
->x
= MP_COPY(ep
->x
);
313 static int dh_decdoit(kem
*k
, dstr
*d
, ghash
*h
)
315 dh_encctx
*de
= (dh_encctx
*)k
;
316 ge
*x
= G_CREATE(de
->g
);
317 size_t n
= de
->g
->noctets
;
318 void *p
= xmalloc(n
);
322 buf_init(&b
, d
->buf
, d
->len
);
323 if (G_FROMRAW(de
->g
, &b
, x
) || group_check(de
->g
, x
))
325 G_EXP(de
->g
, x
, x
, de
->x
);
327 G_TORAW(de
->g
, &b
, x
);
328 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
329 GH_HASH(h
, d
->buf
, d
->len
);
337 static const kemops dh_decops
= {
338 dh_privfetch
, sizeof(dh_priv
),
339 dh_decinit
, dh_decdoit
, dh_enccheck
, dh_encdestroy
342 static const kemops bindh_decops
= {
343 dh_privfetch
, sizeof(dh_priv
),
344 bindh_decinit
, dh_decdoit
, dh_enccheck
, dh_encdestroy
347 static const kemops ec_decops
= {
348 ec_privfetch
, sizeof(ec_priv
),
349 ec_decinit
, dh_decdoit
, dh_enccheck
, dh_encdestroy
352 /* --- The switch table --- */
354 const struct kemtab kemtab
[] = {
355 { "rsa", &rsa_encops
, &rsa_decops
},
356 { "dh", &dh_encops
, &dh_decops
},
357 { "bindh", &bindh_encops
, &bindh_decops
},
358 { "ec", &ec_encops
, &ec_decops
},
362 /* --- @getkem@ --- *
364 * Arguments: @key *k@ = the key to load
365 * @const char *app@ = application name
366 * @int wantpriv@ = nonzero if we want to decrypt
368 * Returns: A key-encapsulating thing.
373 kem
*getkem(key
*k
, const char *app
, int wantpriv
)
375 const char *kalg
, *halg
= 0, *calg
= 0;
382 const struct kemtab
*kt
;
388 /* --- Setup stuff --- */
392 /* --- Get the KEM name --- *
394 * Take the attribute if it's there; otherwise use the key type.
398 if ((q
= key_getattr(0, k
, "kem")) != 0) {
401 } else if (strncmp(k
->type
, app
, n
) == 0 && k
->type
[n
] == '-') {
402 dstr_puts(&d
, k
->type
);
405 die(EXIT_FAILURE
, "no KEM for key `%s'", t
.buf
);
408 /* --- Grab the encryption scheme --- *
410 * Grab it from the KEM if it's there, but override it from the attribute.
413 if (p
&& (p
= strchr(p
, '/')) != 0) {
417 if ((q
= key_getattr(0, k
, "cipher")) != 0)
420 /* --- Grab the hash function --- */
422 if (p
&& (p
= strchr(p
, '/')) != 0) {
426 if ((q
= key_getattr(0, k
, "hash")) != 0)
429 /* --- Instantiate the KEM --- */
431 for (kt
= kemtab
; kt
->name
; kt
++) {
432 if (strcmp(kt
->name
, kalg
) == 0)
435 die(EXIT_FAILURE
, "key encapsulation mechanism `%s' not found in key `%s'",
438 ko
= wantpriv ? kt
->decops
: kt
->encops
;
439 kd
= xmalloc(ko
->kdsz
);
440 kp
= key_fetchinit(ko
->kf
, 0, kd
);
441 if ((e
= key_fetch(kp
, k
)) != 0)
442 die(EXIT_FAILURE
, "error fetching key `%s': %s", t
.buf
, key_strerror(e
));
443 kk
= ko
->init(k
, kd
);
448 /* --- Set up the algorithms --- */
452 else if ((kk
->h
= ghash_byname(halg
)) == 0) {
453 die(EXIT_FAILURE
, "hash algorithm `%s' not found in key `%s'",
458 kk
->c
= &blowfish_cbc
;
459 else if ((kk
->c
= gcipher_byname(calg
)) == 0) {
460 die(EXIT_FAILURE
, "encryption scheme `%s' not found in key `%s'",
465 if ((q
= key_getattr(0, k
, "kdf")) == 0) {
466 dstr_putf(&d
, "%s-mgf", kk
->h
->name
);
469 if ((kk
->cx
= gcipher_byname(q
)) == 0) {
470 die(EXIT_FAILURE
, "encryption scheme (KDF) `%s' not found in key `%s'",
475 if ((q
= key_getattr(0, k
, "mac")) == 0) {
476 dstr_putf(&d
, "%s-hmac", kk
->h
->name
);
479 if ((kk
->m
= gmac_byname(q
)) == 0) {
481 "message authentication code `%s' not found in key `%s'",
485 /* --- Tidy up --- */
492 /* --- @setupkem@ --- *
494 * Arguments: @kem *k@ = key-encapsulation thing
495 * @dstr *d@ = key-encapsulation data
496 * @gcipher **cx@ = key-expansion function (for IVs)
497 * @gcipher **c@ = where to put initialized encryption scheme
498 * @gmac **m@ = where to put initialized MAC
500 * Returns: Zero on success, nonzero on failure.
502 * Use: Initializes all the various symmetric things from a KEM.
505 int setupkem(kem
*k
, dstr
*d
, gcipher
**cx
, gcipher
**c
, gmac
**m
)
513 if (k
->ops
->doit(k
, d
, h
))
515 n
= keysz(GH_CLASS(h
)->hashsz
, k
->cx
->keysz
);
519 *cx
= GC_INIT(k
->cx
, kd
, n
);
521 cn
= keysz(0, k
->c
->keysz
); n
= cn
;
522 mn
= keysz(0, k
->m
->keysz
); if (mn
> n
) n
= mn
;
524 GC_ENCRYPT(*cx
, 0, kd
, cn
);
525 *c
= GC_INIT(k
->c
, kd
, cn
);
526 GC_ENCRYPT(*cx
, 0, kd
, mn
);
527 *m
= GM_KEY(k
->m
, kd
, mn
);
536 /* --- @freekem@ --- *
538 * Arguments: @kem *k@ = key-encapsulation thing
542 * Use: Frees up a key-encapsulation thing.
547 key_fetchdone(k
->kp
);
552 /*----- That's all, folks -------------------------------------------------*/