libgfshare.h

src/cc/includes/libgfshare.h

@@ -0,0 +1,91 @@
+/*
+ * This file is Copyright Daniel Silverstone <dsilvers@digital-scurf.org> 2006
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#ifndef LIBGFSHARE_H
+#define LIBGFSHARE_H
+#include <stdint.h>
+
+typedef struct _gfshare_ctx gfshare_ctx;
+
+typedef void (*gfshare_rand_func_t)(unsigned char*,long);
+
+/* This will, by default, use random(). It's not very good so you should
+ * replace it (perhaps with a function which reads from /dev/urandom).
+ * If you can't be bothered, be sure to srandom() before you use any
+ * of the gfshare_ctx_enc_* functions
+ */
+extern gfshare_rand_func_t gfshare_fill_rand;
+
+/* ------------------------------------------------------[ Preparation ]---- */
+
+/* Initialise a gfshare context for producing shares */
+gfshare_ctx* gfshare_ctx_init_enc(unsigned char* /* sharenrs */,
+                                  uint32_t /* sharecount */,
+                                  unsigned char /* threshold */,
+                                  uint32_t /* size */);
+
+/* Initialise a gfshare context for recombining shares */
+gfshare_ctx* gfshare_ctx_init_dec(unsigned char* /* sharenrs */,
+                                  uint32_t /* sharecount */,
+                                  uint32_t /* size */);
+
+/* Free a share context's memory. */
+void gfshare_ctx_free(gfshare_ctx* /* ctx */);
+
+/* --------------------------------------------------------[ Splitting ]---- */
+
+/* Provide a secret to the encoder. (this re-scrambles the coefficients) */
+void gfshare_ctx_enc_setsecret(gfshare_ctx* /* ctx */,
+                               unsigned char* /* secret */);
+
+/* Extract a share from the context. 
+ * 'share' must be preallocated and at least 'size' bytes long.
+ * 'sharenr' is the index into the 'sharenrs' array of the share you want.
+ */
+void gfshare_ctx_encgetshare(uint8_t *logs,uint8_t *exps,gfshare_ctx* /* ctx */, unsigned char /* sharenr */, unsigned char* /* share */);
+void gfshare_ctx_enc_getshare(gfshare_ctx* /* ctx */, unsigned char /* sharenr */, unsigned char* /* share */);
+
+/* ----------------------------------------------------[ Recombination ]---- */
+
+/* Inform a recombination context of a change in share indexes */
+void gfshare_ctx_dec_newshares(gfshare_ctx* /* ctx */,
+                               unsigned char* /* sharenrs */);
+
+/* Provide a share context with one of the shares.
+ * The 'sharenr' is the index into the 'sharenrs' array
+ */
+void gfshare_ctx_dec_giveshare(gfshare_ctx* /* ctx */,
+                               unsigned char /* sharenr */,
+                               unsigned char* /* share */);
+
+/* Extract the secret by interpolation of the shares.
+ * secretbuf must be allocated and at least 'size' bytes long
+ */
+
+void gfshare_ctx_decextract(uint8_t *logs,uint8_t *exps,gfshare_ctx* /* ctx */, unsigned char* /* secretbuf */);
+void gfshare_ctx_dec_extract(gfshare_ctx* /* ctx */, unsigned char* /* secretbuf */);
+
+#endif /* LIBGFSHARE_H */
+