[u/mdw/catacomb] / gdsa.c

/* -*-c-*-
 *
 * $Id$
 *
 * Generalized version of DSA
 *
 * (c) 2004 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include "gdsa.h"
#include "group.h"
#include "ghash.h"
#include "mpbarrett.h"
#include "mprand.h"

/*----- Main code ---------------------------------------------------------*/

/* --- @gdsa_beginhash@ --- *
 *
 * Arguments:	@const gdsa *c@ = pointer to the context structure
 *
 * Returns:	A hashing context for you to hash the message.
 *
 * Use:		Initializes a hash function correctly for you to hash a
 *		message.  Requires @h@.
 */

ghash *gdsa_beginhash(const gdsa *c) { return (GH_INIT(c->h)); }

/* --- @gdsa_endhash@ --- *
 *
 * Arguments:	@const gdsa *c@ = pointer to the context structure
 *		@ghash *h@ = the hashing context
 *
 * Returns:	---
 *
 * Use:		Does any final thing that DSA wants to do when hashing a
 *		message.  (Actually, there's nothing.)  The hashing context
 *		isn't finalized.
 */

void gdsa_endhash(const gdsa *c, ghash *h) { ; }

/* --- @gdsa_sign@ --- *
 *
 * Arguments:	@const gdsa *c@ = my context structure
 *		@gdsa_sig *s@ = where to put the signature (initialized)
 *		@const void *m@ = pointer to message hash
 *		@mp *k@ = random exponent for this message or null
 *
 * Returns:	---
 *
 * Use:		Signs a message.  Requires @g@, @u@, @h@, and @r@ if @k@ is
 *		null.  This is a better idea than inventing @k@ yourself.
 */

void gdsa_sign(const gdsa *c, gdsa_sig *s, const void *m, mp *k)
{
  group *g = c->g;
  mp *mr = mp_loadb(MP_NEW, m, c->h->hashsz);
  ge *z = G_CREATE(g);
  mp *sr = s->r, *ss = s->s;
  mpbarrett b;

  if (k) { MP_COPY(k); goto have_k; }
new_k:
  k = mprand_range(k, g->r, c->r, 0);
have_k:
  if (MP_ZEROP(k)) goto new_k;
  G_EXP(g, z, g->g, k);
  sr = G_TOINT(g, sr, z); assert(sr);
  if (MP_ZEROP(sr)) goto new_k;

  mp_div(0, &sr, sr, g->r);
  mpbarrett_create(&b, g->r);
  ss = mp_mul(ss, sr, c->u); ss = mpbarrett_reduce(&b, ss, ss);
  ss = mp_add(ss, ss, mr); mp_div(0, &ss, ss, g->r);
  k = mp_modinv(k, k, g->r);
  ss = mp_mul(ss, ss, k); ss = mpbarrett_reduce(&b, ss, ss);
  s->r = sr; s->s = ss;
  mp_drop(k); mp_drop(mr); mpbarrett_destroy(&b); G_DESTROY(g, z);
}

/* --- @gdsa_verify@ --- *
 *
 * Arguments:	@const gdsa *c@ = my context structure
 *		@const gdsa_sig *s@ = the signature to verify
 *		@const void *m@ = pointer to message hash
 *
 * Returns:	Zero if OK, negative on failure.
 *
 * Use:		Checks a signature on a message,  Requires @g@, @p@ and @h@.
 */

int gdsa_verify(const gdsa *c, const gdsa_sig *s, const void *m)
{
  group *g = c->g;
  group_expfactor e[2];
  mpbarrett b;
  mp *h, *t;
  ge *w;
  int rc = -1;

  if (MP_CMP(s->r, <, MP_ONE) || MP_CMP(s->r, >=, g->r) ||
      MP_CMP(s->s, <, MP_ONE) || MP_CMP(s->s, >=, g->r))
    return (-1);
  mpbarrett_create(&b, g->r); h = mp_modinv(MP_NEW, s->s, g->r);
  e[0].base = g->g; e[1].base = c->p;
  t = mp_loadb(MP_NEW, m, c->h->hashsz); mp_div(0, &t, t, g->r);
  t = mp_mul(t, t, h); e[0].exp = t = mpbarrett_reduce(&b, t, t);
  h = mp_mul(h, s->r, h); e[1].exp = h = mpbarrett_reduce(&b, h, h);
  w = G_CREATE(g); G_MEXP(g, w, e, 2);
  t = G_TOINT(g, t, w); if (!t) goto done;
  mp_div(0, &t, t, g->r); if (MP_EQ(t, s->r)) rc = 0;
done:
  G_DESTROY(g, w); mp_drop(t); mp_drop(h); mpbarrett_destroy(&b);
  return (rc);
}

/*----- Test rig ----------------------------------------------------------*/

#ifdef TEST_RIG

static group *getgroup(const char *p) {
  group *g; qd_parse qd;
  qd.p = p; qd.e = 0; g = group_parse(&qd);
  if (g && !qd_eofp(&qd)) { G_DESTROYGROUP(g); g = 0; qd.e = "junk at eof"; }
  if (!g) { fprintf(stderr, "bad group string `%.*s|%s': %s\n", qd.p - p,
		    p, qd.p, qd.e); exit(1); }
  return (g);
}

static ge *getge(group *g, const char *p) {
  ge *x = G_CREATE(g);
  if (group_readstring(g, x, p, 0)) {
    fprintf(stderr, "bad group element `%s'\n", p);
    exit(1);
  }
  return (x);
}

static void showge(group *g, const char *p, ge *x) {
  fprintf(stderr, "*** %s = ", p); group_writefile(g, x, stderr);
  putc('\n', stderr);
}

static void showmp(const char *p, mp *x, int r) {
  fprintf(stderr, "*** %s = ", p); mp_writefile(x, stderr, r); 
  putc('\n', stderr);
}

static int tsign(dstr *v)
{
  gdsa c;
  gdsa_sig s, ss = GDSA_SIG_INIT;
  ghash *h;
  mp *k;
  int ok = 1;

  c.g = getgroup(v[0].buf); c.h = ghash_byname(v[1].buf);
  c.u = *(mp **)v[2].buf; k = *(mp **)v[4].buf;
  s.r = *(mp **)v[5].buf; s.s = *(mp **)v[6].buf;

  h = gdsa_beginhash(&c);
  GH_HASH(h, v[3].buf, v[3].len);
  gdsa_endhash(&c, h);
  gdsa_sign(&c, &ss, GH_DONE(h, 0), k);
  if (!MP_EQ(s.r, ss.r) || !MP_EQ(s.s, ss.s)) {
    ok = 0;
    fprintf(stderr, "*** sign failed!\n");
    fprintf(stderr, "*** group: %s\n", v[0].buf);
    fprintf(stderr, "*** hash: %s\n", c.h->name);
    showmp("private key", c.u, 16);
    fprintf(stderr, "*** message: `%s'\n", v[3].buf);
    showmp("computed r", ss.r, 16); showmp("computed s", ss.s, 16);
    showmp("expected r", s.r, 16); showmp("expected s", s.s, 16);
  }
  mp_drop(s.r); mp_drop(s.s); mp_drop(ss.r); mp_drop(ss.s);
  mp_drop(k); mp_drop(c.u); G_DESTROYGROUP(c.g); GH_DESTROY(h);
  assert(mparena_count(MPARENA_GLOBAL) == 0);
  return (ok);
}

static int tverify(dstr *v)
{
  gdsa c;
  gdsa_sig s;
  ghash *h;
  int rc, erc;
  int ok = 1;

  c.g = getgroup(v[0].buf); c.h = ghash_byname(v[1].buf);
  c.p = getge(c.g, v[2].buf);
  s.r = *(mp **)v[4].buf; s.s = *(mp **)v[5].buf;
  erc = *(int *)v[6].buf;

  h = gdsa_beginhash(&c);
  GH_HASH(h, v[3].buf, v[3].len);
  gdsa_endhash(&c, h);
  rc = gdsa_verify(&c, &s, GH_DONE(h, 0));
  if (!rc != !erc) {
    ok = 0;
    fprintf(stderr, "*** verify failed!\n");
    fprintf(stderr, "*** group: %s\n", v[0].buf);
    fprintf(stderr, "*** hash: %s\n", c.h->name);
    showge(c.g, "public key", c.p);
    fprintf(stderr, "*** message: `%s'\n", v[3].buf);
    showmp("sig r", s.r, 16); showmp("sig s", s.s, 16);
    fprintf(stderr, "*** expected %s\n", !erc ? "pass" : "fail");
  }
  mp_drop(s.r); mp_drop(s.s); G_DESTROY(c.g, c.p); G_DESTROYGROUP(c.g);
  GH_DESTROY(h);
  assert(mparena_count(MPARENA_GLOBAL) == 0);
  return (ok);
}

static const test_chunk tests[] = {
  { "sign", tsign, { &type_string, &type_string, &type_mp, &type_string,
		     &type_mp, &type_mp, &type_mp } },
  { "verify", tverify, { &type_string, &type_string, &type_string,
			 &type_string, &type_mp, &type_mp, &type_int } },
  { 0 }
};

int main(int argc, char *argv[])
{
  sub_init();
  test_run(argc, argv, tests, SRCDIR "/tests/gdsa");
  return (0);
}

#endif

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
e9026a0a	1	/* --c--
e9026a0a	2	*
a69a3efd	3	* $Id$
e9026a0a	4	*
	5	* Generalized version of DSA
	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
e9026a0a	30	/----- Header files ------------------------------------------------------/
	31
	32	#include "gdsa.h"
	33	#include "group.h"
	34	#include "ghash.h"
	35	#include "mpbarrett.h"
	36	#include "mprand.h"
	37
	38	/----- Main code ---------------------------------------------------------/
	39
	40	/* --- @gdsa_beginhash@ --- *
	41	*
	42	* Arguments: @const gdsa *c@ = pointer to the context structure
	43	*
	44	* Returns: A hashing context for you to hash the message.
	45	*
	46	* Use: Initializes a hash function correctly for you to hash a
	47	* message. Requires @h@.
	48	*/
	49
	50	ghash gdsa_beginhash(const gdsa c) { return (GH_INIT(c->h)); }
	51
	52	/* --- @gdsa_endhash@ --- *
	53	*
	54	* Arguments: @const gdsa *c@ = pointer to the context structure
	55	* @ghash *h@ = the hashing context
	56	*
	57	* Returns: ---
	58	*
	59	* Use: Does any final thing that DSA wants to do when hashing a
	60	* message. (Actually, there's nothing.) The hashing context
	61	* isn't finalized.
	62	*/
	63
f4535c64	64	void gdsa_endhash(const gdsa c, ghash h) { ; }
e9026a0a	65
	66	/* --- @gdsa_sign@ --- *
	67	*
	68	* Arguments: @const gdsa *c@ = my context structure
	69	* @gdsa_sig *s@ = where to put the signature (initialized)
	70	* @const void *m@ = pointer to message hash
	71	* @mp *k@ = random exponent for this message or null
	72	*
	73	* Returns: ---
	74	*
	75	* Use: Signs a message. Requires @g@, @u@, @h@, and @r@ if @k@ is
	76	* null. This is a better idea than inventing @k@ yourself.
	77	*/
	78
	79	void gdsa_sign(const gdsa c, gdsa_sig s, const void m, mp k)
	80	{
	81	group *g = c->g;
	82	mp *mr = mp_loadb(MP_NEW, m, c->h->hashsz);
	83	ge *z = G_CREATE(g);
	84	mp sr = s->r, ss = s->s;
	85	mpbarrett b;
	86
	87	if (k) { MP_COPY(k); goto have_k; }
	88	new_k:
	89	k = mprand_range(k, g->r, c->r, 0);
	90	have_k:
a69a3efd	91	if (MP_ZEROP(k)) goto new_k;
e9026a0a	92	G_EXP(g, z, g->g, k);
e9026a0a	93	sr = G_TOINT(g, sr, z); assert(sr);
a69a3efd	94	if (MP_ZEROP(sr)) goto new_k;
e9026a0a	95
	96	mp_div(0, &sr, sr, g->r);
	97	mpbarrett_create(&b, g->r);
	98	ss = mp_mul(ss, sr, c->u); ss = mpbarrett_reduce(&b, ss, ss);
	99	ss = mp_add(ss, ss, mr); mp_div(0, &ss, ss, g->r);
b817bfc6	100	k = mp_modinv(k, k, g->r);
e9026a0a	101	ss = mp_mul(ss, ss, k); ss = mpbarrett_reduce(&b, ss, ss);
	102	s->r = sr; s->s = ss;
	103	mp_drop(k); mp_drop(mr); mpbarrett_destroy(&b); G_DESTROY(g, z);
	104	}
	105
	106	/* --- @gdsa_verify@ --- *
	107	*
	108	* Arguments: @const gdsa *c@ = my context structure
	109	* @const gdsa_sig *s@ = the signature to verify
	110	* @const void *m@ = pointer to message hash
	111	*
	112	* Returns: Zero if OK, negative on failure.
	113	*
	114	* Use: Checks a signature on a message, Requires @g@, @p@ and @h@.
	115	*/
	116
	117	int gdsa_verify(const gdsa c, const gdsa_sig s, const void *m)
	118	{
	119	group *g = c->g;
	120	group_expfactor e[2];
	121	mpbarrett b;
b817bfc6	122	mp h, t;
e9026a0a	123	ge *w;
	124	int rc = -1;
	125
	126	if (MP_CMP(s->r, <, MP_ONE) \|\| MP_CMP(s->r, >=, g->r) \|\|
	127	MP_CMP(s->s, <, MP_ONE) \|\| MP_CMP(s->s, >=, g->r))
	128	return (-1);
b817bfc6	129	mpbarrett_create(&b, g->r); h = mp_modinv(MP_NEW, s->s, g->r);
e9026a0a	130	e[0].base = g->g; e[1].base = c->p;
	131	t = mp_loadb(MP_NEW, m, c->h->hashsz); mp_div(0, &t, t, g->r);
	132	t = mp_mul(t, t, h); e[0].exp = t = mpbarrett_reduce(&b, t, t);
	133	h = mp_mul(h, s->r, h); e[1].exp = h = mpbarrett_reduce(&b, h, h);
	134	w = G_CREATE(g); G_MEXP(g, w, e, 2);
	135	t = G_TOINT(g, t, w); if (!t) goto done;
	136	mp_div(0, &t, t, g->r); if (MP_EQ(t, s->r)) rc = 0;
	137	done:
	138	G_DESTROY(g, w); mp_drop(t); mp_drop(h); mpbarrett_destroy(&b);
	139	return (rc);
	140	}
	141
	142	/----- Test rig ----------------------------------------------------------/
	143
	144	#ifdef TEST_RIG
	145
	146	static group getgroup(const char p) {
	147	group *g; qd_parse qd;
	148	qd.p = p; qd.e = 0; g = group_parse(&qd);
	149	if (g && !qd_eofp(&qd)) { G_DESTROYGROUP(g); g = 0; qd.e = "junk at eof"; }
	150	if (!g) { fprintf(stderr, "bad group string `%.*s\|%s': %s\n", qd.p - p,
	151	p, qd.p, qd.e); exit(1); }
	152	return (g);
	153	}
	154
	155	static ge getge(group g, const char *p) {
	156	ge *x = G_CREATE(g);
	157	if (group_readstring(g, x, p, 0)) {
	158	fprintf(stderr, "bad group element `%s'\n", p);
	159	exit(1);
	160	}
	161	return (x);
	162	}
	163
	164	static void showge(group g, const char p, ge *x) {
	165	fprintf(stderr, "*** %s = ", p); group_writefile(g, x, stderr);
	166	putc('\n', stderr);
	167	}
	168
	169	static void showmp(const char p, mp x, int r) {
	170	fprintf(stderr, "*** %s = ", p); mp_writefile(x, stderr, r);
	171	putc('\n', stderr);
	172	}
	173
	174	static int tsign(dstr *v)
	175	{
	176	gdsa c;
	177	gdsa_sig s, ss = GDSA_SIG_INIT;
	178	ghash *h;
	179	mp *k;
	180	int ok = 1;
	181
	182	c.g = getgroup(v[0].buf); c.h = ghash_byname(v[1].buf);
	183	c.u = (mp )v[2].buf; k = (mp **)v[4].buf;
	184	s.r = (mp )v[5].buf; s.s = (mp **)v[6].buf;
	185
	186	h = gdsa_beginhash(&c);
	187	GH_HASH(h, v[3].buf, v[3].len);
	188	gdsa_endhash(&c, h);
	189	gdsa_sign(&c, &ss, GH_DONE(h, 0), k);
	190	if (!MP_EQ(s.r, ss.r) \|\| !MP_EQ(s.s, ss.s)) {
	191	ok = 0;
	192	fprintf(stderr, "*** sign failed!\n");
	193	fprintf(stderr, "*** group: %s\n", v[0].buf);
194	fprintf(stderr, "*** hash: %s\n", c.h->name);
195	showmp("private key", c.u, 16);
196	fprintf(stderr, "*** message: `%s'\n", v[3].buf);
197	showmp("computed r", ss.r, 16); showmp("computed s", ss.s, 16);
198	showmp("expected r", s.r, 16); showmp("expected s", s.s, 16);
199	}
200	mp_drop(s.r); mp_drop(s.s); mp_drop(ss.r); mp_drop(ss.s);
201	mp_drop(k); mp_drop(c.u); G_DESTROYGROUP(c.g); GH_DESTROY(h);
202	assert(mparena_count(MPARENA_GLOBAL) == 0);
203	return (ok);
204	}
205
206	static int tverify(dstr *v)
207	{
208	gdsa c;
209	gdsa_sig s;
210	ghash *h;
211	int rc, erc;
212	int ok = 1;
213
214	c.g = getgroup(v[0].buf); c.h = ghash_byname(v[1].buf);
215	c.p = getge(c.g, v[2].buf);
216	s.r = (mp )v[4].buf; s.s = (mp **)v[5].buf;
217	erc = (int )v[6].buf;
218
219	h = gdsa_beginhash(&c);
220	GH_HASH(h, v[3].buf, v[3].len);
221	gdsa_endhash(&c, h);
222	rc = gdsa_verify(&c, &s, GH_DONE(h, 0));
223	if (!rc != !erc) {
224	ok = 0;
225	fprintf(stderr, "*** verify failed!\n");
226	fprintf(stderr, "*** group: %s\n", v[0].buf);
227	fprintf(stderr, "*** hash: %s\n", c.h->name);
228	showge(c.g, "public key", c.p);
229	fprintf(stderr, "*** message: `%s'\n", v[3].buf);
230	showmp("sig r", s.r, 16); showmp("sig s", s.s, 16);
231	fprintf(stderr, "*** expected %s\n", !erc ? "pass" : "fail");
232	}
233	mp_drop(s.r); mp_drop(s.s); G_DESTROY(c.g, c.p); G_DESTROYGROUP(c.g);
234	GH_DESTROY(h);
235	assert(mparena_count(MPARENA_GLOBAL) == 0);
236	return (ok);
237	}
238
239	static const test_chunk tests[] = {
240	{ "sign", tsign, { &type_string, &type_string, &type_mp, &type_string,
241	&type_mp, &type_mp, &type_mp } },
242	{ "verify", tverify, { &type_string, &type_string, &type_string,
243	&type_string, &type_mp, &type_mp, &type_int } },
244	{ 0 }
245	};
246
247	int main(int argc, char *argv[])
248	{
249	sub_init();
250	test_run(argc, argv, tests, SRCDIR "/tests/gdsa");
251	return (0);
252	}
253
254	#endif
255
256	/----- That's all, folks -------------------------------------------------/