X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/5d4fee2a9d2ecf4d2566c0deca27e1878bf2380f..df82bc85db06b9cd8917aec33aadaf151d9d4a46:/gfshare.h

diff --git a/gfshare.h b/gfshare.h
index fe09d8a..9826758 100644
--- a/gfshare.h
+++ b/gfshare.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: gfshare.h,v 1.6 2000/12/06 20:30:10 mdw Exp $
+ * $Id$
  *
  * Secret sharing over %$\gf{2^8}$%
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,43 +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: gfshare.h,v $
- * Revision 1.6  2000/12/06 20:30:10  mdw
- * Change secret sharing interface: present the secret at share
- * construction time.
- *
- * Revision 1.5  2000/06/24 19:11:47  mdw
- * Fix daft error in the comment for @gfshare_get@.
- *
- * Revision 1.4  2000/06/24 18:29:05  mdw
- * Interface change: allow shares to be extracted from a context on demand,
- * rather than building them all up-front.
- *
- * Revision 1.3  2000/06/18 23:12:15  mdw
- * Change typesetting of Galois Field names.
- *
- * Revision 1.2  2000/06/17 11:05:27  mdw
- * Add a commentary on the system.
- *
- * Revision 1.1  2000/06/17 10:56:30  mdw
- * Fast but nonstandard secret sharing system.
- *
- */
-
 /*----- Notes on the system -----------------------------------------------*
  *
  * This uses a variant of Shamir's secret sharing system.  Shamir's original
@@ -97,6 +72,8 @@ typedef struct gfshare {
 
 #define GFSHARE_INIT(t, sz) { t, 0, sz, 0 }
 
+#define GFSHARE_INDEX(s, i) ((s)->v[(i) * ((s)->sz + 1)])
+
 /*----- Functions provided ------------------------------------------------*/
 
 /* --- @gfshare_create@ --- *
@@ -158,6 +135,17 @@ extern void gfshare_mkshares(gfshare */*s*/, grand */*r*/,
 
 extern void gfshare_get(gfshare */*s*/, unsigned /*x*/, void */*buf*/);
 
+/* --- @gfshare_addedp@ --- *
+ *
+ * Arguments:	@gfshare *s@ = pointer to sharing context
+ *		@unsigned x@ = which share number to check
+ *
+ * Returns:	Nonzero if share @x@ has been added already, zero if it
+ *		hasn't.
+ */
+
+extern int gfshare_addedp(gfshare */*s*/, unsigned /*x*/);
+
 /* --- @gfshare_add@ --- *
  *
  * Arguments:	@gfshare *s@ = pointer to sharing context