X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/4d47e1571e6a3fd88ebd956a18a4b362d2f98755..f41f820e4b3e230d9314cc4323abf59babdd4e67:/gfshare.h

diff --git a/gfshare.h b/gfshare.h
index 4141156..2d0f73e 100644
--- a/gfshare.h
+++ b/gfshare.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: gfshare.h,v 1.3 2000/06/18 23:12:15 mdw Exp $
+ * $Id: gfshare.h,v 1.5 2000/06/24 19:11:47 mdw Exp $
  *
  * Secret sharing over %$\gf{2^8}$%
  *
@@ -30,6 +30,13 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: gfshare.h,v $
+ * 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.
  *
@@ -77,28 +84,22 @@
 
 /* --- A secret sharing context --- */
 
-typedef struct gfshare_pt {
-  octet x;				/* %$x$%-coordinate of the share */
-  octet *y;				/* Pointer to share payload */
-} gfshare_pt;
-
 typedef struct gfshare {
   unsigned t;				/* Threshold */
-  unsigned n;				/* The number of shares to make */
   unsigned i;				/* Next free slot in vector */
   size_t sz;				/* Size of the secret and shares */
-  octet *s;				/* The secret */
-  gfshare_pt *v;			/* Vector of share information */
+  void *s;				/* The secret */
+  octet *v;				/* Vector of share information */
 } gfshare;
 
-#define GFSHARE_INIT(t, n, sz) { t, n, 0, sz, 0, 0 }
+#define GFSHARE_INIT(t, sz) { t, 0, sz, 0, 0 }
 
 /*----- Functions provided ------------------------------------------------*/
 
 /* --- @gfshare_create@ --- *
  *
  * Arguments:	@gfshare *s@ = pointer to share context to initialize
- *		@unsigned t, n@ = threshold parameters for the system
+ *		@unsigned t@ = threshold for the system
  *		@size_t sz@ = size of the secret
  *
  * Returns:	---
@@ -106,8 +107,7 @@ typedef struct gfshare {
  * Use:		Initializes a sharing context.
  */
 
-extern void gfshare_create(gfshare */*s*/, unsigned /*t*/, unsigned /*n*/,
-			   size_t /*sz*/);
+extern void gfshare_create(gfshare */*s*/, unsigned /*t*/, size_t /*sz*/);
 
 /* --- @gfshare_destroy@ --- *
  *
@@ -129,23 +129,35 @@ extern void gfshare_destroy(gfshare */*s*/);
  *
  * 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@, @ssz@ 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@ 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.
  */
 
 extern void gfshare_mkshares(gfshare */*s*/, grand */*r*/);
 
+/* --- @gfshare_get@ --- *
+ *
+ * Arguments:	@gfshare *s@ = pointer to share conext
+ *		@unsigned x@ = share index to fetch
+ *		@void *buf@ = pointer to output buffer
+ *
+ * Returns:	---
+ *
+ * Use:		Extracts a share from the system.  You may extract up to 255
+ *		shares from the system.  Shares are indexed from 0.
+ */
+
+extern void gfshare_get(gfshare */*s*/, unsigned /*x*/, void */*buf*/);
+
 /* --- @gfshare_add@ --- *
  *
  * Arguments:	@gfshare *s@ = pointer to sharing context
  *		@unsigned x@ = which share number this is
- *		@const octet *y@ = the share value
+ *		@const void *y@ = the share value
  *
  * Returns:	Number of shares required before recovery may be performed.
  *
@@ -154,19 +166,19 @@ extern void gfshare_mkshares(gfshare */*s*/, grand */*r*/);
  */
 
 extern unsigned gfshare_add(gfshare */*s*/,
-			    unsigned /*x*/, const octet */*y*/);
+			    unsigned /*x*/, const void */*y*/);
 
 /* --- @gfshare_combine@ --- *
  *
  * Arguments:	@gfshare *s@ = pointer to share context
- *		@octet *buf@ = pointer to output buffer for the secret
+ *		@void *buf@ = pointer to output buffer for the secret
  *
  * Returns:	---
  *
  * Use:		Reconstructs a secret, given enough shares.
  */
 
-extern void gfshare_combine(gfshare */*s*/, octet */*buf*/);
+extern void gfshare_combine(gfshare */*s*/, void */*buf*/);
 
 /*----- That's all, folks -------------------------------------------------*/