X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/8b810a45dec25017a6256e4ef134236444a00921..ab9168949ec2762698d6293adf17b637f30b891e:/dsa-verify.c

diff --git a/dsa-verify.c b/dsa-verify.c
index 217cede..90895b4 100644
--- a/dsa-verify.c
+++ b/dsa-verify.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: dsa-verify.c,v 1.1 1999/11/19 19:28:00 mdw Exp $
+ * $Id: dsa-verify.c,v 1.7 2004/04/08 01:36:15 mdw Exp $
  *
  * DSA signature verification
  *
  * (c) 1999 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,26 +15,18 @@
  * 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: dsa-verify.c,v $
- * Revision 1.1  1999/11/19 19:28:00  mdw
- * Implementation of the Digital Signature Algorithm.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include "dsa.h"
@@ -46,23 +38,20 @@
 /* --- @dsa_vrfy@ --- *
  *
  * Arguments:	@const dsa_param *dp@ = pointer to DSA parameters
- *		@const mp *y@ = public verification key
- *		@const mp *m@ = message which was signed
- *		@const mp *r, *s@ = the signature
+ *		@mp *y@ = public verification key
+ *		@mp *m@ = message which was signed
+ *		@mp *r, *s@ = the signature
  *
  * Returns:	Zero if the signature is a forgery, nonzero if it's valid.
  *
  * Use:		Verifies a DSA digital signature.
  */
 
-#define SHOW(x) do { fputs(#x " = ", stdout); mp_writefile(x, stdout, 16); fputc('\n', stdout); } while (0)
-
-int dsa_vrfy(const dsa_param *dp, const mp *y,
-	     const mp *m, const mp *r, const mp *s)
+int dsa_vrfy(const dsa_param *dp, mp *y, mp *m, mp *r, mp *s)
 {
   mpmont pm, qm;
   mp *w;
-  mpmont_factor f[2];
+  mp_expfactor f[2];
   int ok;
 
   /* --- Ensure that all of the signature bits are in range --- */
@@ -80,13 +69,12 @@ int dsa_vrfy(const dsa_param *dp, const mp *y,
   /* --- Compute %$w = s^{-1} \bmod q$% --- */
 
   {
-    mp *z;
-    mp_gcd(0, 0, &z, dp->q, (mp *)s);
+    mp *z = mp_modinv(MP_NEW, s, dp->q);
     w = mpmont_mul(&qm, MP_NEW, z, qm.r2);
     mp_drop(z);
   }
 
-  /* --- Compute %$wr%$ and %$wm$% --- */
+  /* --- Compute %$wr$% and %$wm$% --- */
 
   f[0].exp = mpmont_mul(&qm, MP_NEW, w, m);
   f[1].exp = mpmont_mul(&qm, MP_NEW, w, r);
@@ -96,10 +84,10 @@ int dsa_vrfy(const dsa_param *dp, const mp *y,
   /* --- Do the exponentiation and take residue mod @q@ --- */
 
   f[0].base = dp->g;
-  f[1].base = (mp *)y;
-  w = mpmont_mexp(&pm, f, 2);
+  f[1].base = y;
+  w = mpmont_mexp(&pm, MP_NEW, f, 2);
   mp_div(0, &w, w, dp->q);
-  ok = MP_CMP(w, ==, r);
+  ok = MP_EQ(w, r);
 
   /* --- Tidy up --- */
 
@@ -113,7 +101,7 @@ int dsa_vrfy(const dsa_param *dp, const mp *y,
 /* --- @dsa_verify@ --- *
  *
  * Arguments:	@const dsa_param *dp@ = pointer to DSA parameters
- *		@const mp *y@ = public verification key
+ *		@mp *y@ = public verification key
  *		@const void *m@ = pointer to message block
  *		@size_t msz@ = size of message block
  *		@const void *r@ = pointer to @r@ signature half
@@ -126,12 +114,12 @@ int dsa_vrfy(const dsa_param *dp, const mp *y,
  * Use:		Verifies a DSA digital signature.
  */
 
-int dsa_verify(const dsa_param *dp, const mp *y,
+int dsa_verify(const dsa_param *dp, mp *y,
 	       const void *m, size_t msz,
 	       const void *r, size_t rsz,
 	       const void *s, size_t ssz)
 {
-  mp *mm = mp_loadb(MP_NEW, m, msz);
+  mp *mm = dsa_h2n(MP_NEW, dp->q, m, msz);
   mp *rm = mp_loadb(MP_NEW, r, rsz);
   mp *sm = mp_loadb(MP_NEW, s, ssz);
   int ok = dsa_vrfy(dp, y, mm, rm, sm);
@@ -190,6 +178,7 @@ static int verify(int good, dstr *v)
   mp_drop(dp.q);
   mp_drop(dp.g);
   mp_drop(y);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }