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
)
174 dh_encctx
*de
= CREATE(dh_encctx
);
178 if ((de
->g
= group_prime(gp
)) == 0)
179 die(EXIT_FAILURE
, "bad prime group in key `%s'", t
.buf
);
181 de
->y
= G_CREATE(de
->g
);
182 if (G_FROMINT(de
->g
, de
->y
, y
))
183 die(EXIT_FAILURE
, "bad public key `%s'", t
.buf
);
188 static dh_encctx
*ec_doinit(key
*k
, const char *cstr
, const ec
*y
)
190 dh_encctx
*de
= CREATE(dh_encctx
);
196 if ((e
= ec_getinfo(&ei
, cstr
)) != 0 ||
197 (de
->g
= group_ec(&ei
)) == 0)
198 die(EXIT_FAILURE
, "bad elliptic curve spec in key `%s': %s", t
.buf
, e
);
200 de
->y
= G_CREATE(de
->g
);
201 if (G_FROMEC(de
->g
, de
->y
, y
))
202 die(EXIT_FAILURE
, "bad public curve point `%s'", t
.buf
);
207 static kem
*dh_encinit(key
*k
, void *kd
)
210 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
);
214 static kem
*ec_encinit(key
*k
, void *kd
)
217 dh_encctx
*de
= ec_doinit(k
, ep
->cstr
, &ep
->p
);
221 static int dh_encdoit(kem
*k
, dstr
*d
, ghash
*h
)
223 dh_encctx
*de
= (dh_encctx
*)k
;
224 mp
*r
= mprand_range(MP_NEW
, de
->g
->r
, &rand_global
, 0);
225 ge
*x
= G_CREATE(de
->g
);
226 ge
*y
= G_CREATE(de
->g
);
227 size_t n
= de
->g
->noctets
;
230 G_EXP(de
->g
, x
, de
->g
->g
, r
);
231 G_EXP(de
->g
, y
, de
->y
, r
);
233 buf_init(&b
, d
->buf
, n
);
234 G_TORAW(de
->g
, &b
, y
);
235 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
236 buf_init(&b
, d
->buf
, n
);
237 G_TORAW(de
->g
, &b
, x
);
238 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
246 static const char *dh_enccheck(kem
*k
)
248 dh_encctx
*de
= (dh_encctx
*)k
;
250 if ((e
= G_CHECK(de
->g
, &rand_global
)) != 0)
252 if (group_check(de
->g
, de
->y
))
253 return ("public key not in subgroup");
257 static void dh_encdestroy(kem
*k
)
259 dh_encctx
*de
= (dh_encctx
*)k
;
260 G_DESTROY(de
->g
, de
->y
);
262 G_DESTROYGROUP(de
->g
);
265 static const kemops dh_encops
= {
266 dh_pubfetch
, sizeof(dh_pub
),
267 dh_encinit
, dh_encdoit
, dh_enccheck
, dh_encdestroy
270 static const kemops ec_encops
= {
271 ec_pubfetch
, sizeof(ec_pub
),
272 ec_encinit
, dh_encdoit
, dh_enccheck
, dh_encdestroy
275 static kem
*dh_decinit(key
*k
, void *kd
)
278 dh_encctx
*de
= dh_doinit(k
, &dp
->dp
, dp
->y
);
279 de
->x
= MP_COPY(dp
->x
);
283 static kem
*ec_decinit(key
*k
, void *kd
)
286 dh_encctx
*de
= ec_doinit(k
, ep
->cstr
, &ep
->p
);
287 de
->x
= MP_COPY(ep
->x
);
291 static int dh_decdoit(kem
*k
, dstr
*d
, ghash
*h
)
293 dh_encctx
*de
= (dh_encctx
*)k
;
294 ge
*x
= G_CREATE(de
->g
);
295 size_t n
= de
->g
->noctets
;
296 void *p
= xmalloc(n
);
300 buf_init(&b
, d
->buf
, d
->len
);
301 if (G_FROMRAW(de
->g
, &b
, x
) || group_check(de
->g
, x
))
303 G_EXP(de
->g
, x
, x
, de
->x
);
305 G_TORAW(de
->g
, &b
, x
);
306 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
307 GH_HASH(h
, d
->buf
, d
->len
);
315 static const kemops dh_decops
= {
316 dh_privfetch
, sizeof(dh_priv
),
317 dh_decinit
, dh_decdoit
, dh_enccheck
, dh_encdestroy
320 static const kemops ec_decops
= {
321 ec_privfetch
, sizeof(ec_priv
),
322 ec_decinit
, dh_decdoit
, dh_enccheck
, dh_encdestroy
325 /* --- The switch table --- */
327 const struct kemtab kemtab
[] = {
328 { "rsa", &rsa_encops
, &rsa_decops
},
329 { "dh", &dh_encops
, &dh_decops
},
330 { "ec", &ec_encops
, &ec_decops
},
334 /* --- @getkem@ --- *
336 * Arguments: @key *k@ = the key to load
337 * @const char *app@ = application name
338 * @int wantpriv@ = nonzero if we want to decrypt
340 * Returns: A key-encapsulating thing.
345 kem
*getkem(key
*k
, const char *app
, int wantpriv
)
347 const char *kalg
, *halg
= 0, *calg
= 0;
354 const struct kemtab
*kt
;
360 /* --- Setup stuff --- */
364 /* --- Get the KEM name --- *
366 * Take the attribute if it's there; otherwise use the key type.
370 if ((q
= key_getattr(0, k
, "kem")) != 0) {
373 } else if (strncmp(k
->type
, app
, n
) == 0 && k
->type
[n
] == '-') {
374 dstr_puts(&d
, k
->type
);
377 die(EXIT_FAILURE
, "no KEM for key `%s'", t
.buf
);
380 /* --- Grab the encryption scheme --- *
382 * Grab it from the KEM if it's there, but override it from the attribute.
385 if (p
&& (p
= strchr(p
, '/')) != 0) {
389 if ((q
= key_getattr(0, k
, "cipher")) != 0)
392 /* --- Grab the hash function --- */
394 if (p
&& (p
= strchr(p
, '/')) != 0) {
398 if ((q
= key_getattr(0, k
, "hash")) != 0)
401 /* --- Instantiate the KEM --- */
403 for (kt
= kemtab
; kt
->name
; kt
++) {
404 if (strcmp(kt
->name
, kalg
) == 0)
407 die(EXIT_FAILURE
, "key encapsulation mechanism `%s' not found in key `%s'",
410 ko
= wantpriv ? kt
->decops
: kt
->encops
;
411 kd
= xmalloc(ko
->kdsz
);
412 kp
= key_fetchinit(ko
->kf
, 0, kd
);
413 if ((e
= key_fetch(kp
, k
)) != 0)
414 die(EXIT_FAILURE
, "error fetching key `%s': %s", t
.buf
, key_strerror(e
));
415 kk
= ko
->init(k
, kd
);
420 /* --- Set up the algorithms --- */
424 else if ((kk
->h
= ghash_byname(halg
)) == 0) {
425 die(EXIT_FAILURE
, "hash algorithm `%s' not found in key `%s'",
430 kk
->c
= &blowfish_cbc
;
431 else if ((kk
->c
= gcipher_byname(calg
)) == 0) {
432 die(EXIT_FAILURE
, "encryption scheme `%s' not found in key `%s'",
437 if ((q
= key_getattr(0, k
, "kdf")) == 0) {
438 dstr_putf(&d
, "%s-mgf", kk
->h
->name
);
441 if ((kk
->cx
= gcipher_byname(q
)) == 0) {
442 die(EXIT_FAILURE
, "encryption scheme (KDF) `%s' not found in key `%s'",
447 if ((q
= key_getattr(0, k
, "mac")) == 0) {
448 dstr_putf(&d
, "%s-hmac", kk
->h
->name
);
451 if ((kk
->m
= gmac_byname(q
)) == 0) {
453 "message authentication code `%s' not found in key `%s'",
457 /* --- Tidy up --- */
464 /* --- @setupkem@ --- *
466 * Arguments: @kem *k@ = key-encapsulation thing
467 * @dstr *d@ = key-encapsulation data
468 * @gcipher **cx@ = key-expansion function (for IVs)
469 * @gcipher **c@ = where to put initialized encryption scheme
470 * @gmac **m@ = where to put initialized MAC
472 * Returns: Zero on success, nonzero on failure.
474 * Use: Initializes all the various symmetric things from a KEM.
477 int setupkem(kem
*k
, dstr
*d
, gcipher
**cx
, gcipher
**c
, gmac
**m
)
485 if (k
->ops
->doit(k
, d
, h
))
487 n
= keysz(GH_CLASS(h
)->hashsz
, k
->cx
->keysz
);
491 *cx
= GC_INIT(k
->cx
, kd
, n
);
493 cn
= keysz(0, k
->c
->keysz
); n
= cn
;
494 mn
= keysz(0, k
->m
->keysz
); if (mn
> n
) n
= mn
;
496 GC_ENCRYPT(*cx
, 0, kd
, cn
);
497 *c
= GC_INIT(k
->c
, kd
, cn
);
498 GC_ENCRYPT(*cx
, 0, kd
, mn
);
499 *m
= GM_KEY(k
->m
, kd
, mn
);
508 /* --- @freekem@ --- *
510 * Arguments: @kem *k@ = key-encapsulation thing
514 * Use: Frees up a key-encapsulation thing.
519 key_fetchdone(k
->kp
);
524 /*----- That's all, folks -------------------------------------------------*/