5c3f75ec |
1 | /* -*-c-*- |
2 | * |
c65df279 |
3 | * $Id$ |
5c3f75ec |
4 | * |
5 | * Catcrypt key-encapsulation |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
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. |
18 | * |
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. |
23 | * |
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, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <stdlib.h> |
33 | |
34 | #include <mLib/alloc.h> |
35 | #include <mLib/dstr.h> |
36 | #include <mLib/report.h> |
37 | #include <mLib/sub.h> |
38 | |
39 | #include "mprand.h" |
40 | #include "rand.h" |
41 | |
42 | #include "ec.h" |
43 | #include "ec-keys.h" |
44 | #include "dh.h" |
45 | #include "rsa.h" |
46 | |
47 | #include "rmd160.h" |
48 | #include "blowfish-cbc.h" |
49 | |
50 | #include "cc.h" |
51 | |
52 | /*----- Key encapsulation -------------------------------------------------*/ |
53 | |
54 | /* --- RSA --- */ |
55 | |
56 | typedef struct rsa_encctx { |
57 | kem k; |
58 | rsa_pubctx rp; |
59 | } rsa_encctx; |
60 | |
61 | static kem *rsa_encinit(key *k, void *kd) |
62 | { |
63 | rsa_encctx *re = CREATE(rsa_encctx); |
64 | rsa_pubcreate(&re->rp, kd); |
65 | return (&re->k); |
66 | } |
67 | |
68 | static int rsa_encdoit(kem *k, dstr *d, ghash *h) |
69 | { |
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); |
74 | dstr_ensure(d, n); |
75 | mp_storeb(x, d->buf, n); |
76 | GH_HASH(h, d->buf, n); |
77 | mp_storeb(y, d->buf, n); |
78 | d->len += n; |
79 | mp_drop(x); |
80 | mp_drop(y); |
81 | return (0); |
82 | } |
83 | |
84 | static const char *rsa_lengthcheck(mp *n) |
85 | { |
86 | if (mp_bits(n) < 1020) return ("key too short"); |
87 | return (0); |
88 | } |
89 | |
90 | static const char *rsa_enccheck(kem *k) |
91 | { |
92 | rsa_encctx *re = (rsa_encctx *)k; |
93 | const char *e; |
94 | if ((e = rsa_lengthcheck(re->rp.rp->n)) != 0) return (e); |
95 | return (0); |
96 | } |
97 | |
98 | static void rsa_encdestroy(kem *k) |
99 | { |
100 | rsa_encctx *re = (rsa_encctx *)k; |
101 | rsa_pubdestroy(&re->rp); |
102 | DESTROY(re); |
103 | } |
104 | |
105 | static const kemops rsa_encops = { |
106 | rsa_pubfetch, sizeof(rsa_pub), |
107 | rsa_encinit, rsa_encdoit, rsa_enccheck, rsa_encdestroy |
108 | }; |
109 | |
110 | typedef struct rsa_decctx { |
111 | kem k; |
112 | rsa_privctx rp; |
113 | } rsa_decctx; |
114 | |
115 | static kem *rsa_decinit(key *k, void *kd) |
116 | { |
117 | rsa_decctx *rd = CREATE(rsa_decctx); |
118 | rsa_privcreate(&rd->rp, kd, &rand_global); |
119 | return (&rd->k); |
120 | } |
121 | |
122 | static int rsa_decdoit(kem *k, dstr *d, ghash *h) |
123 | { |
124 | rsa_decctx *rd = (rsa_decctx *)k; |
125 | mp *x = mp_loadb(MP_NEW, d->buf, d->len); |
126 | size_t n; |
127 | char *p; |
128 | |
129 | if (MP_CMP(x, >=, rd->rp.rp->n)) { |
130 | mp_drop(x); |
131 | return (-1); |
132 | } |
133 | n = mp_octets(rd->rp.rp->n); |
134 | p = xmalloc(n); |
135 | x = rsa_privop(&rd->rp, x, x); |
136 | mp_storeb(x, p, n); |
137 | GH_HASH(h, p, n); |
138 | mp_drop(x); |
139 | xfree(p); |
140 | return (0); |
141 | } |
142 | |
143 | static const char *rsa_deccheck(kem *k) |
144 | { |
145 | rsa_decctx *rd = (rsa_decctx *)k; |
146 | const char *e; |
147 | if ((e = rsa_lengthcheck(rd->rp.rp->n)) != 0) return (e); |
148 | return (0); |
149 | } |
150 | |
151 | static void rsa_decdestroy(kem *k) |
152 | { |
153 | rsa_decctx *rd = (rsa_decctx *)k; |
154 | rsa_privdestroy(&rd->rp); |
155 | DESTROY(rd); |
156 | } |
157 | |
158 | static const kemops rsa_decops = { |
159 | rsa_privfetch, sizeof(rsa_priv), |
160 | rsa_decinit, rsa_decdoit, rsa_deccheck, rsa_decdestroy |
161 | }; |
162 | |
163 | /* --- DH and EC --- */ |
164 | |
165 | typedef struct dh_encctx { |
166 | kem k; |
167 | group *g; |
168 | mp *x; |
169 | ge *y; |
170 | } dh_encctx; |
171 | |
172 | static dh_encctx *dh_doinit(key *k, const gprime_param *gp, mp *y) |
173 | { |
174 | dh_encctx *de = CREATE(dh_encctx); |
175 | dstr t = DSTR_INIT; |
176 | |
177 | key_fulltag(k, &t); |
178 | if ((de->g = group_prime(gp)) == 0) |
179 | die(EXIT_FAILURE, "bad prime group in key `%s'", t.buf); |
180 | de->x = MP_NEW; |
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); |
184 | dstr_destroy(&t); |
185 | return (de); |
186 | } |
187 | |
188 | static dh_encctx *ec_doinit(key *k, const char *cstr, const ec *y) |
189 | { |
190 | dh_encctx *de = CREATE(dh_encctx); |
191 | ec_info ei; |
192 | const char *e; |
193 | dstr t = DSTR_INIT; |
194 | |
195 | key_fulltag(k, &t); |
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); |
199 | de->x = MP_NEW; |
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); |
203 | dstr_destroy(&t); |
204 | return (de); |
205 | } |
206 | |
207 | static kem *dh_encinit(key *k, void *kd) |
208 | { |
209 | dh_pub *dp = kd; |
210 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y); |
211 | return (&de->k); |
212 | } |
213 | |
214 | static kem *ec_encinit(key *k, void *kd) |
215 | { |
216 | ec_pub *ep = kd; |
217 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
218 | return (&de->k); |
219 | } |
220 | |
221 | static int dh_encdoit(kem *k, dstr *d, ghash *h) |
222 | { |
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; |
228 | buf b; |
229 | |
230 | G_EXP(de->g, x, de->g->g, r); |
231 | G_EXP(de->g, y, de->y, r); |
232 | dstr_ensure(d, n); |
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)); |
239 | d->len += BLEN(&b); |
240 | mp_drop(r); |
241 | G_DESTROY(de->g, x); |
242 | G_DESTROY(de->g, y); |
243 | return (0); |
244 | } |
245 | |
246 | static const char *dh_enccheck(kem *k) |
247 | { |
248 | dh_encctx *de = (dh_encctx *)k; |
249 | const char *e; |
250 | if ((e = G_CHECK(de->g, &rand_global)) != 0) |
251 | return (0); |
252 | if (group_check(de->g, de->y)) |
253 | return ("public key not in subgroup"); |
254 | return (0); |
255 | } |
256 | |
257 | static void dh_encdestroy(kem *k) |
258 | { |
259 | dh_encctx *de = (dh_encctx *)k; |
260 | G_DESTROY(de->g, de->y); |
261 | mp_drop(de->x); |
262 | G_DESTROYGROUP(de->g); |
263 | } |
264 | |
265 | static const kemops dh_encops = { |
266 | dh_pubfetch, sizeof(dh_pub), |
267 | dh_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
268 | }; |
269 | |
270 | static const kemops ec_encops = { |
271 | ec_pubfetch, sizeof(ec_pub), |
272 | ec_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
273 | }; |
274 | |
275 | static kem *dh_decinit(key *k, void *kd) |
276 | { |
277 | dh_priv *dp = kd; |
278 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y); |
279 | de->x = MP_COPY(dp->x); |
280 | return (&de->k); |
281 | } |
282 | |
283 | static kem *ec_decinit(key *k, void *kd) |
284 | { |
285 | ec_priv *ep = kd; |
286 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
287 | de->x = MP_COPY(ep->x); |
288 | return (&de->k); |
289 | } |
290 | |
291 | static int dh_decdoit(kem *k, dstr *d, ghash *h) |
292 | { |
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); |
297 | buf b; |
298 | int rc = -1; |
299 | |
300 | buf_init(&b, d->buf, d->len); |
301 | if (G_FROMRAW(de->g, &b, x) || group_check(de->g, x)) |
302 | goto done; |
303 | G_EXP(de->g, x, x, de->x); |
304 | buf_init(&b, p, n); |
305 | G_TORAW(de->g, &b, x); |
306 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
307 | GH_HASH(h, d->buf, d->len); |
308 | rc = 0; |
309 | done: |
310 | G_DESTROY(de->g, x); |
311 | xfree(p); |
312 | return (rc); |
313 | } |
314 | |
315 | static const kemops dh_decops = { |
316 | dh_privfetch, sizeof(dh_priv), |
317 | dh_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
318 | }; |
319 | |
320 | static const kemops ec_decops = { |
321 | ec_privfetch, sizeof(ec_priv), |
322 | ec_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
323 | }; |
324 | |
325 | /* --- The switch table --- */ |
326 | |
c65df279 |
327 | const struct kemtab kemtab[] = { |
5c3f75ec |
328 | { "rsa", &rsa_encops, &rsa_decops }, |
329 | { "dh", &dh_encops, &dh_decops }, |
330 | { "ec", &ec_encops, &ec_decops }, |
331 | { 0, 0, 0 } |
332 | }; |
333 | |
334 | /* --- @getkem@ --- * |
335 | * |
336 | * Arguments: @key *k@ = the key to load |
337 | * @const char *app@ = application name |
338 | * @int wantpriv@ = nonzero if we want to decrypt |
339 | * |
340 | * Returns: A key-encapsulating thing. |
341 | * |
342 | * Use: Loads a key. |
343 | */ |
344 | |
345 | kem *getkem(key *k, const char *app, int wantpriv) |
346 | { |
347 | const char *kalg, *halg = 0, *calg = 0; |
348 | dstr d = DSTR_INIT; |
349 | dstr t = DSTR_INIT; |
350 | size_t n; |
351 | char *p = 0; |
352 | const char *q; |
353 | kem *kk; |
354 | const struct kemtab *kt; |
355 | const kemops *ko; |
356 | void *kd; |
357 | int e; |
358 | key_packdef *kp; |
359 | |
360 | /* --- Setup stuff --- */ |
361 | |
362 | key_fulltag(k, &t); |
363 | |
364 | /* --- Get the KEM name --- * |
365 | * |
366 | * Take the attribute if it's there; otherwise use the key type. |
367 | */ |
368 | |
369 | n = strlen(app); |
370 | if ((q = key_getattr(0, k, "kem")) != 0) { |
371 | dstr_puts(&d, q); |
372 | p = d.buf; |
373 | } else if (strncmp(k->type, app, n) == 0 && k->type[n] == '-') { |
374 | dstr_puts(&d, k->type); |
375 | p = d.buf + n + 1; |
376 | } else |
377 | die(EXIT_FAILURE, "no KEM for key `%s'", t.buf); |
378 | kalg = p; |
379 | |
380 | /* --- Grab the encryption scheme --- * |
381 | * |
382 | * Grab it from the KEM if it's there, but override it from the attribute. |
383 | */ |
384 | |
385 | if (p && (p = strchr(p, '/')) != 0) { |
386 | *p++ = 0; |
387 | calg = p; |
388 | } |
389 | if ((q = key_getattr(0, k, "cipher")) != 0) |
390 | calg = q; |
391 | |
392 | /* --- Grab the hash function --- */ |
393 | |
394 | if (p && (p = strchr(p, '/')) != 0) { |
395 | *p++ = 0; |
396 | halg = p; |
397 | } |
398 | if ((q = key_getattr(0, k, "hash")) != 0) |
399 | halg = q; |
400 | |
401 | /* --- Instantiate the KEM --- */ |
402 | |
403 | for (kt = kemtab; kt->name; kt++) { |
404 | if (strcmp(kt->name, kalg) == 0) |
405 | goto k_found; |
406 | } |
407 | die(EXIT_FAILURE, "key encapsulation mechanism `%s' not found in key `%s'", |
408 | kalg, t.buf); |
409 | k_found:; |
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); |
416 | kk->kp = kp; |
417 | kk->ops = ko; |
418 | kk->kd = kd; |
419 | |
420 | /* --- Set up the algorithms --- */ |
421 | |
422 | if (!halg) |
423 | kk->h = &rmd160; |
424 | else if ((kk->h = ghash_byname(halg)) == 0) { |
425 | die(EXIT_FAILURE, "hash algorithm `%s' not found in key `%s'", |
426 | halg, t.buf); |
427 | } |
428 | |
429 | if (!calg) |
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'", |
433 | calg, t.buf); |
434 | } |
435 | |
436 | dstr_reset(&d); |
437 | if ((q = key_getattr(0, k, "kdf")) == 0) { |
438 | dstr_putf(&d, "%s-mgf", kk->h->name); |
439 | q = d.buf; |
440 | } |
441 | if ((kk->cx = gcipher_byname(q)) == 0) { |
442 | die(EXIT_FAILURE, "encryption scheme (KDF) `%s' not found in key `%s'", |
443 | q, t.buf); |
444 | } |
445 | |
446 | dstr_reset(&d); |
447 | if ((q = key_getattr(0, k, "mac")) == 0) { |
448 | dstr_putf(&d, "%s-hmac", kk->h->name); |
449 | q = d.buf; |
450 | } |
451 | if ((kk->m = gmac_byname(q)) == 0) { |
452 | die(EXIT_FAILURE, |
453 | "message authentication code `%s' not found in key `%s'", |
454 | q, t.buf); |
455 | } |
456 | |
457 | /* --- Tidy up --- */ |
458 | |
459 | dstr_destroy(&d); |
460 | dstr_destroy(&t); |
461 | return (kk); |
462 | } |
463 | |
464 | /* --- @setupkem@ --- * |
465 | * |
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 |
471 | * |
472 | * Returns: Zero on success, nonzero on failure. |
473 | * |
474 | * Use: Initializes all the various symmetric things from a KEM. |
475 | */ |
476 | |
477 | int setupkem(kem *k, dstr *d, gcipher **cx, gcipher **c, gmac **m) |
478 | { |
479 | octet *kd; |
480 | size_t n, cn, mn; |
481 | ghash *h; |
c65df279 |
482 | int rc = -1; |
5c3f75ec |
483 | |
484 | h = GH_INIT(k->h); |
485 | if (k->ops->doit(k, d, h)) |
486 | goto done; |
487 | n = keysz(GH_CLASS(h)->hashsz, k->cx->keysz); |
488 | if (!n) |
489 | goto done; |
490 | kd = GH_DONE(h, 0); |
491 | *cx = GC_INIT(k->cx, kd, n); |
492 | |
493 | cn = keysz(0, k->c->keysz); n = cn; |
494 | mn = keysz(0, k->m->keysz); if (mn > n) n = mn; |
495 | kd = xmalloc(n); |
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); |
500 | xfree(kd); |
501 | |
502 | rc = 0; |
503 | done: |
504 | GH_DESTROY(h); |
505 | return (rc); |
506 | } |
507 | |
508 | /* --- @freekem@ --- * |
509 | * |
510 | * Arguments: @kem *k@ = key-encapsulation thing |
511 | * |
512 | * Returns: --- |
513 | * |
514 | * Use: Frees up a key-encapsulation thing. |
515 | */ |
516 | |
517 | void freekem(kem *k) |
518 | { |
519 | key_fetchdone(k->kp); |
520 | xfree(k->kd); |
521 | k->ops->destroy(k); |
522 | } |
523 | |
524 | /*----- That's all, folks -------------------------------------------------*/ |