catcrypt: Implement symmetric key-encapsulation and signature schemes.

[u/mdw/catacomb] / gdsa.c

diff --git a/gdsa.c b/gdsa.c
index 8723847..f60fb2d 100644 (file)
--- a/gdsa.c
+++ b/gdsa.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: gdsa.c,v 1.1 2004/04/04 19:42:59 mdw Exp $
+ * $Id$
  *
  * Generalized version of DSA
  *
@@ -27,14 +27,6 @@
  * 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"
@@ -69,7 +61,7 @@ ghash *gdsa_beginhash(const gdsa *c) { return (GH_INIT(c->h)); }
  *             isn't finalized.
  */
 
-void gdsa_endhash(gdsa *c, ghash *h) { ; }
+void gdsa_endhash(const gdsa *c, ghash *h) { ; }
 
 /* --- @gdsa_sign@ --- *
  *
@@ -96,16 +88,16 @@ void gdsa_sign(const gdsa *c, gdsa_sig *s, const void *m, mp *k)
 new_k:
   k = mprand_range(k, g->r, c->r, 0);
 have_k:
-  if (MP_ISZERO(k)) goto new_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_ISZERO(sr)) goto new_k;
+  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);
-  mp_gcd(0, 0, &k, g->r, k);
+  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);
@@ -127,14 +119,14 @@ 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;
+  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); mp_gcd(0, 0, &h, g->r, s->s);
+  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);