X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/71dfe576992502b96b601a7e3dce7a9d98e1682e..1589affab225db500965e2cb869c534d6860e6bd:/share.h

diff --git a/share.h b/share.h
index 9584378..a875e06 100644
--- a/share.h
+++ b/share.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: share.h,v 1.1 2000/06/17 12:09:38 mdw Exp $
+ * $Id: share.h,v 1.3 2000/12/06 20:30:10 mdw Exp $
  *
  * Shamir's secret sharing
  *
@@ -30,6 +30,14 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: share.h,v $
+ * Revision 1.3  2000/12/06 20:30:10  mdw
+ * Change secret sharing interface: present the secret at share
+ * construction time.
+ *
+ * Revision 1.2  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 1.1  2000/06/17 12:09:38  mdw
  * Shamir's secret sharing system.
  *
@@ -75,28 +83,26 @@ 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 +120,35 @@ 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 void share_mkshares(share */*s*/, grand */*r*/);
+extern mp *share_get(share */*s*/, mp */*d*/, unsigned /*x*/);
 
 /* --- @share_add@ --- *
  *