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/* This file is part of libbrandt.
* Copyright (C) 2016 GNUnet e.V.
*
* libbrandt is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* libbrandt 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* libbrandt. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file smc.c
* @brief Implementation of the smc primitives.
*/
#include <gcrypt.h>
#include "crypto.h"
#include "smc.h"
#include "util.h"
extern gcry_ctx_t ec_ctx;
/**
* smc_zkp_dl
*
* @param v TODO
* @param g TODO
* @param x TODO
* @param a TODO
* @param c TODO
* @param r TODO
*/
void
smc_zkp_dl (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_t x,
gcry_mpi_point_t *a, gcry_mpi_t *c,
gcry_mpi_t *r)
{
gcry_mpi_t z = gcry_mpi_new (0);
brandt_ec_keypair_create_base (a, &z, g);
/* compute challange c */
/**TODO: generate c from HASH(g,v,a) and don't output it */
brandt_ec_skey_create (c);
*r = gcry_mpi_new (0);
gcry_mpi_mul (*r, *c, x);
gcry_mpi_add (*r, *r, z);
gcry_mpi_release (z);
}
/**
* smc_zkp_dl_check
*
* @param v TODO
* @param g TODO
* @param a TODO
* @param c TODO
* @param r TODO
* @return 0 if the proof is correct, something else otherwise
*/
int
smc_zkp_dl_check (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_point_t a,
gcry_mpi_t c,
gcry_mpi_t r)
{
int ret;
gcry_mpi_point_t left = gcry_mpi_point_new (0);
gcry_mpi_point_t right = gcry_mpi_point_new (0);
gcry_mpi_ec_mul (left, r, g, ec_ctx);
gcry_mpi_ec_mul (right, c, v, ec_ctx);
gcry_mpi_ec_add (right, a, right, ec_ctx);
ret = brandt_ec_point_cmp (left, right);
gcry_mpi_point_release (left);
gcry_mpi_point_release (right);
return ret;
}
void
smc_zkp_2dle (gcry_mpi_point_t v, gcry_mpi_point_t w, gcry_mpi_point_t g1, gcry_mpi_point_t g2, gcry_mpi_t x, gcry_mpi_point_t *a, gcry_mpi_point_t *b, gcry_mpi_t *c, gcry_mpi_t *r)
{
gcry_mpi_t z = gcry_mpi_new (0);
brandt_ec_keypair_create_base (a, &z, g1);
*b = gcry_mpi_point_new(0);
gcry_mpi_ec_mul(*b, z, g2, ec_ctx);
/* compute challange c */
/**TODO: generate c from HASH(g1,g2,v,w,a,b) and don't output it */
brandt_ec_skey_create (c);
*r = gcry_mpi_new (0);
gcry_mpi_mul (*r, *c, x);
gcry_mpi_add (*r, *r, z);
gcry_mpi_release (z);
}
int
smc_zkp_2dle_check (gcry_mpi_point_t v, gcry_mpi_point_t w, gcry_mpi_point_t g1, gcry_mpi_point_t g2, gcry_mpi_point_t a, gcry_mpi_point_t b, gcry_mpi_t c, gcry_mpi_t r)
{
int ret;
gcry_mpi_point_t left = gcry_mpi_point_new (0);
gcry_mpi_point_t right = gcry_mpi_point_new (0);
gcry_mpi_ec_mul (left, r, g1, ec_ctx);
gcry_mpi_ec_mul (right, c, v, ec_ctx);
gcry_mpi_ec_add (right, a, right, ec_ctx);
ret = brandt_ec_point_cmp (left, right);
gcry_mpi_ec_mul (left, r, g2, ec_ctx);
gcry_mpi_ec_mul (right, c, w, ec_ctx);
gcry_mpi_ec_add (right, b, right, ec_ctx);
ret &= brandt_ec_point_cmp (left, right);
gcry_mpi_point_release (left);
gcry_mpi_point_release (right);
return ret;
}
//GEN
//smc_hextodec (const char *s)
//{
// size_t i;
// char c;
// pari_sp ltop = avma;
// GEN ret = gen_0;
//
// for (i = 0; i < strlen (s); i++)
// {
// errno = 0;
// if (1 != sscanf (&s[i], "%1hhx", &c))
// {
// brandt_eprintf ("failed to parse hex (\"%s\") to decimal:", s);
// return NULL;
// }
// ret = addis (shifti (ret, 4), c);
// }
// return gerepilecopy (ltop, ret);
//}
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