--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: gdsa.c,v 1.1 2004/04/04 19:42:59 mdw Exp $
+ *
+ * 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.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: gdsa.c,v $
+ * Revision 1.1 2004/04/04 19:42:59 mdw
+ * Add set -e.
+ *
+ */
+
+/*----- 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(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_ISZERO(k)) goto new_k;
+ G_EXP(g, z, g->g, k);
+ sr = G_TOINT(g, sr, z); assert(sr);
+ if (MP_ISZERO(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);
+ mp_gcd(0, 0, &k, g->r, k);
+ 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 = MP_NEW, *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); mp_gcd(0, 0, &h, g->r, s->s);
+ 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 -------------------------------------------------*/
projects / u / mdw / catacomb / blobdiff