ct.c, ct.h: New constant-time operations.

[u/mdw/catacomb] / share.h

diff --git a/share.h b/share.h
index 9584378..5500a4c 100644 (file)
--- a/share.h
+++ b/share.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: share.h,v 1.1 2000/06/17 12:09:38 mdw Exp $
+ * $Id$
  *
  * Shamir's secret sharing
  *
  * (c) 2000 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: share.h,v $
- * Revision 1.1  2000/06/17 12:09:38  mdw
- * Shamir's secret sharing system.
- *
- */
-
 /*----- Notes on the sharing system ---------------------------------------*
  *
  * Shamir's secret-sharing system is based on polynomial interpolation modulo
@@ -75,28 +67,26 @@ typedef struct share_pt {
 
 typedef struct share {
   unsigned t;                          /* Threshold */
-  unsigned n;                          /* The number of shares to make */
   unsigned i;                          /* Next free slot in the vector */
-  mp *s;                               /* The secret */
   mp *p;                               /* Modulus for arithmetic */
   share_pt *v;                         /* Vector of share information */
 } share;
 
-#define SHARE_INIT(t, n) { t, n, 0, 0, 0, 0 }
+#define SHARE_INIT(t) { t, 0, 0, 0 }
 
 /*----- Functions provided ------------------------------------------------*/
 
 /* --- @share_create@ --- *
  *
  * Arguments:  @share *s@ = pointer to share context to initialize
- *             @unsigned t, n@ = threshold parameters for the system
+ *             @unsigned t@ = threshold for the system
  *
  * Returns:    ---
  *
  * Use:                Initializes a sharing context.
  */
 
-extern void share_create(share */*s*/, unsigned /*t*/, unsigned /*n*/);
+extern void share_create(share */*s*/, unsigned /*t*/);
 
 /* --- @share_destroy@ --- *
  *
@@ -114,21 +104,46 @@ extern void share_destroy(share */*s*/);
  *
  * Arguments:  @share *s@ = pointer to share context to fill in
  *             @grand *r@ = pointer to random number source
+ *             @mp *n@ = the secret to share
  *
  * Returns:    ---
  *
- * Use:                Generates @c->n@ secret shares, such that any @c->t@ of them
- *             may be used to recover the secret.
- *
+ * Use:                Initializes a sharing context to be able to create shares.
  *             The context structure is expected to be mostly filled in.  In
- *             particular, @t@, @n@ and @s@ must be initialized.  If @p@ is
- *             zero, a prime number of appropriate size is generated
- *             automatically.  If @v@ is zero, a vector of appropriate size
- *             is allocated.  You should use the macro @SHARE_INIT@ or
- *             @share_create@ to construct sharing contexts.
+ *             particular, @t@ must be initialized.  If @p@ is zero, a prime
+ *             number of appropriate size is generated automatically.  If
+ *             @v@ is zero, a vector of appropriate size is allocated.  You
+ *             should use the macro @SHARE_INIT@ or @share_create@ to
+ *             construct sharing contexts.
+ */
+
+extern void share_mkshares(share */*s*/, grand */*r*/, mp */*n*/);
+
+/* --- @share_get@ --- *
+ *
+ * Arguments:  @share *s@ = pointer to share conext
+ *             @mp *d@ = destination for the share
+ *             @unsigned x@ = share index to fetch
+ *
+ * Returns:    The share, as requested.
+ *
+ * Use:                Extracts a share from the system.  You may extract @MPW_MAX@
+ *             shares, or @s->p@ shares from the system, whichever is
+ *             smaller.  Shares are indexed from 0.
+ */
+
+extern mp *share_get(share */*s*/, mp */*d*/, unsigned /*x*/);
+
+/* --- @share_addedp@ --- *
+ *
+ * Arguments:  @share *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 void share_mkshares(share */*s*/, grand */*r*/);
+extern int share_addedp(share */*s*/, unsigned /*x*/);
 
 /* --- @share_add@ --- *
  *