Merge branch 'master' of git+ssh://metalzone.distorted.org.uk/~mdw/public-git/catacomb/

[u/mdw/catacomb] / dsa-sign.c

diff --git a/dsa-sign.c b/dsa-sign.c
index 8e5c997..9bb4a5b 100644 (file)
--- a/dsa-sign.c
+++ b/dsa-sign.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: dsa-sign.c,v 1.1 1999/11/19 19:28:00 mdw Exp $
+ * $Id: dsa-sign.c,v 1.3 2004/04/08 01:36:15 mdw Exp $
  *
  * DSA signing operation
  *
@@ -27,18 +27,11 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: dsa-sign.c,v $
- * Revision 1.1  1999/11/19 19:28:00  mdw
- * Implementation of the Digital Signature Algorithm.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include "dsa.h"
 #include "mp.h"
+#include "mpbarrett.h"
 #include "mpmont.h"
 
 /*----- Main code ---------------------------------------------------------*/
@@ -46,9 +39,9 @@
 /* --- @dsa_mksig@ --- *
  *
  * Arguments:  @const dsa_param *dp@ = pointer to DSA parameters
- *             @const mp *a@ = secret signing key
- *             @const mp *m@ = message to be signed
- *             @const mp *k@ = random data
+ *             @mp *a@ = secret signing key
+ *             @mp *m@ = message to be signed
+ *             @mp *k@ = random data
  *             @mp **rr, **ss@ = where to put output parameters
  *
  * Returns:    ---
@@ -56,45 +49,38 @@
  * Use:                Computes a DSA signature of a message.
  */
 
-void dsa_mksig(const dsa_param *dp, const mp *a, const mp *m, const mp *k,
-              mp **rr, mp **ss)
+void dsa_mksig(const dsa_param *dp, mp *a, mp *m, mp *k, mp **rr, mp **ss)
 {
-  mpmont pm, qm;
+  mpmont pm;
+  mpbarrett qb;
   mp *k1, *r;
-  mp *rrr, *ar;
-
-  /* --- Create the Montgomery contexts --- */
-
-  mpmont_create(&pm, dp->p);
-  mpmont_create(&qm, dp->q);
+  mp *ar;
 
   /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */
 
-  r = mpmont_exp(&pm, dp->g, k);
+  mpmont_create(&pm, dp->p);
+  r = mpmont_exp(&pm, MP_NEW, dp->g, k);
+  mpmont_destroy(&pm);
   mp_div(0, &r, r, dp->q);
-  *rr = r;
 
   /* --- Compute %$k^{-1} \bmod q$% --- */
 
-  mp_gcd(0, 0, &k1, dp->q, (mp *)k);
+  k1 = mp_modinv(MP_NEW, k, dp->q);
 
   /* --- Now for %$k^{-1}(m + ar)$% --- */
 
-  rrr = mpmont_mul(&qm, MP_NEW, r, qm.r2);
-  ar = mpmont_mul(&qm, MP_NEW, a, rrr);
+  mpbarrett_create(&qb, dp->q);
+  ar = mp_mul(MP_NEW, a, r);
   ar = mp_add(ar, ar, m);
-  if (MP_CMP(ar, >=, dp->q))
-    ar = mp_sub(ar, ar, dp->q);
-  rrr = mpmont_mul(&qm, rrr, ar, qm.r2);
-  ar = mpmont_mul(&qm, ar, rrr, k1);
+  ar = mpbarrett_reduce(&qb, ar, ar);
+  ar = mp_mul(ar, ar, k1);
+  ar = mpbarrett_reduce(&qb, ar, ar);
+  mpbarrett_destroy(&qb);
+  MP_DROP(k1);
+  if (*rr) MP_DROP(*rr);
+  if (*ss) MP_DROP(*ss);
+  *rr = r;
   *ss = ar;
-
-  /* --- Tidy things up a little --- */
-
-  mp_drop(rrr);
-  mp_drop(k1);
-  mpmont_destroy(&pm);
-  mpmont_destroy(&qm);
 }
 
 /* --- @dsa_sign@ --- *
@@ -122,7 +108,7 @@ void dsa_sign(dsa_param *dp, mp *a,
 {
   mp *mm = mp_loadb(MP_NEW, m, msz);
   mp *km = mp_loadb(MP_NEW, k, ksz);
-  mp *rm, *sm;
+  mp *rm = MP_NEW, *sm = MP_NEW;
   dsa_mksig(dp, a, mm, km, &rm, &sm);
   mp_storeb(rm, r, rsz);
   mp_storeb(sm, s, ssz);
@@ -191,6 +177,7 @@ static int verify(dstr *v)
   mp_drop(dp.q);
   mp_drop(dp.g);
   mp_drop(x);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }