libbrandt/crypto.h

/* 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 crypto.h
 * @brief Interface of the crypto primitives.
 * @author Markus Teich
 */

#ifndef _BRANDT_CRYPTO_H
#define _BRANDT_CRYPTO_H

#include <gcrypt.h>
#include <stdint.h>

#include "internals.h"

void brandt_crypto_init ();


/* --- HASHING --- */

struct brandt_hash_code {
	uint32_t bits[512 / 8 / sizeof (uint32_t)];   /* = 16 */
};

void brandt_hash (const void *block, size_t size, struct brandt_hash_code *ret);


/* --- EC --- */

/* used for serialized mpis and serialized curve points (they are the same size
 * when compressed) */
struct ec_mpi {
	unsigned char data[256 / 8];
};

int ec_point_cmp (const gcry_mpi_point_t a, const gcry_mpi_point_t b);
void ec_skey_create (gcry_mpi_t skey);
void ec_keypair_create (gcry_mpi_point_t pkey, gcry_mpi_t skey);
void ec_keypair_create_base (gcry_mpi_point_t       pkey,
                             gcry_mpi_t             skey,
                             const gcry_mpi_point_t base);


/* --- Zero knowledge proofs --- */

struct proof_dl {
	struct ec_mpi r;
	struct ec_mpi a;
};

struct proof_2dle {
	struct ec_mpi r;
	struct ec_mpi a;
	struct ec_mpi b;
};

struct proof_0og {
	struct ec_mpi a1;
	struct ec_mpi a2;
	struct ec_mpi b1;
	struct ec_mpi b2;
	struct ec_mpi d1;
	struct ec_mpi d2;
	struct ec_mpi r1;
	struct ec_mpi r2;
};

void smc_zkp_dl (gcry_mpi_point_t v,
                 const gcry_mpi_t x,
                 struct proof_dl  *proof);
int smc_zkp_dl_check (const gcry_mpi_point_t v,
                      const struct proof_dl  *proof);

void smc_zkp_2dle (const gcry_mpi_point_t v,
                   const gcry_mpi_point_t w,
                   const gcry_mpi_point_t g1,
                   const gcry_mpi_point_t g2,
                   const gcry_mpi_t       x,
                   struct proof_2dle      *proof);
int smc_zkp_2dle_check (const gcry_mpi_point_t  v,
                        const gcry_mpi_point_t  w,
                        const gcry_mpi_point_t  g1,
                        const gcry_mpi_point_t  g2,
                        const struct proof_2dle *proof);

void smc_zkp_0og (int                    m_is_gen,
                  const gcry_mpi_point_t y,
                  gcry_mpi_t             r,
                  gcry_mpi_point_t       alpha,
                  gcry_mpi_point_t       beta,
                  struct proof_0og       *proof);
int smc_zkp_0og_check (const gcry_mpi_point_t y,
                       const gcry_mpi_point_t alpha,
                       const gcry_mpi_point_t beta,
                       const struct proof_0og *proof);

/* --- Protocol implementation --- */

unsigned char *smc_gen_keyshare (struct AuctionData *ad, size_t *buflen);
int smc_recv_keyshare (struct AuctionData *ad,
                       unsigned char      *buf,
                       size_t             buflen,
                       uint16_t           sender_index);

unsigned char *smc_encrypt_bid (struct AuctionData *ad, size_t *buflen);
int smc_recv_encrypted_bid (struct AuctionData *ad,
                            unsigned char      *buf,
                            size_t             buflen,
                            uint16_t           sender_index);

unsigned char *smc_compute_outcome (struct AuctionData *ad, size_t *buflen);
int smc_recv_outcome (struct AuctionData *ad,
                      unsigned char      *buf,
                      size_t             buflen,
                      uint16_t           sender);
#endif /* ifndef _BRANDT_CRYPTO_H */