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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 "util.h"
#include "smc.h"
extern gcry_ctx_t ec_ctx;
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);
/**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);
}
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;
}
/*
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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