X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/3d64a35c9b151e739eb6a8712915810ea574eac8..b817bfc642225b8c3c0b6a7e42d1fb949b61a606:/gfshare.c

diff --git a/gfshare.c b/gfshare.c
index 0af17cc..a46f948 100644
--- a/gfshare.c
+++ b/gfshare.c
@@ -1,8 +1,8 @@
 /* -*-c-*-
  *
- * $Id: gfshare.c,v 1.4 2000/06/24 18:29:05 mdw Exp $
+ * $Id: gfshare.c,v 1.9 2004/04/08 01:36:15 mdw Exp $
  *
- * Secret sharing over %$\gf(2^8)$%
+ * Secret sharing over %$\gf{2^8}$%
  *
  * (c) 2000 Straylight/Edgeware
  */
@@ -27,25 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: gfshare.c,v $
- * 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  2000/06/22 18:04:13  mdw
- * Improve secret reconstruction -- compute coefficients as needed rather
- * than making a big array of them.
- *
- * Revision 1.2  2000/06/18 23:12:15  mdw
- * Change typesetting of Galois Field names.
- *
- * Revision 1.1  2000/06/17 10:56:30  mdw
- * Fast but nonstandard secret sharing system.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <assert.h>
@@ -63,7 +44,7 @@
 
 /*----- Static variables --------------------------------------------------*/
 
-static octet gflog[] = GFSHARE_LOG, gfexp[] = GFSHARE_EXP;
+static const octet gflog[] = GFSHARE_LOG, gfexp[] = GFSHARE_EXP;
 
 /*----- Main code ---------------------------------------------------------*/
 
@@ -83,7 +64,6 @@ void gfshare_create(gfshare *s, unsigned t, size_t sz)
   s->t = t;
   s->i = 0;
   s->sz = sz;
-  s->s = 0;
   s->v = 0;
 }
 
@@ -108,22 +88,23 @@ void gfshare_destroy(gfshare *s)
  *
  * Arguments:	@gfshare *s@ = pointer to share context to fill in
  *		@grand *r@ = pointer to random number source
+ *		@const void *buf@ = pointer to the secret to share
  *
  * Returns:	---
  *
  * Use:		Initializes a sharing context to be able to create shares.
  *		The context structure is expected to be mostly filled in.  In
- *		particular, @t@ and @s@ must be initialized.  If @v@ is zero,
- *		a vector of appropriate size is allocated.  You should use
- *		the macro @GFSHARE_INIT@ or @gfshare_create@ to construct
- *		sharing contexts.
+ *		particular, @t@ must be initialized.  If @v@ is zero, a
+ *		vector of appropriate size is allocated.  You should use the
+ *		macro @GFSHARE_INIT@ or @gfshare_create@ to construct sharing
+ *		contexts.
  */
 
-void gfshare_mkshares(gfshare *s, grand *r)
+void gfshare_mkshares(gfshare *s, grand *r, const void *buf)
 {
   s->v = XS_ALLOC(s->sz * s->t);
   r->ops->fill(r, s->v, s->sz * (s->t - 1));
-  memcpy(s->v + s->sz * (s->t - 1), s->s, s->sz);
+  memcpy(s->v + s->sz * (s->t - 1), buf, s->sz);
 }
 
 /* --- @gfshare_get@ --- *
@@ -132,7 +113,7 @@ void gfshare_mkshares(gfshare *s, grand *r)
  *		@unsigned x@ = share index to fetch
  *		@void *buf@ = pointer to output buffer
  *
- * Returns:	The share, as requested.
+ * Returns:	---
  *
  * Use:		Extracts a share from the system.  You may extract up to 255
  *		shares from the system.  Shares are indexed from 0.
@@ -287,9 +268,8 @@ static int verify(grand *r)
   r->ops->fill(r, sec, len);
 
   gfshare_create(&s, t, len);
-  s.s = sec;
 
-  gfshare_mkshares(&s, r);
+  gfshare_mkshares(&s, r, sec);
   for (i = 0; i < t; i++)
     gfshare_get(&s, p[i], v + (i * len));
   gfshare_destroy(&s);