/*
     This file is part of GNUnet.
     Copyright (C) 2015 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later

 */
/**
 * @file util/test_crypto_ecc_dlog.c
 * @brief testcase for ECC DLOG calculation
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include <gcrypt.h>


/**
 * Name of the curve we are using.  Note that we have hard-coded
 * structs that use 256 bits, so using a bigger curve will require
 * changes that break stuff badly.  The name of the curve given here
 * must be agreed by all peers and be supported by libgcrypt.
 */
#define CURVE "Ed25519"

/**
 * Maximum value we test dlog for.
 */
#define MAX_FACT 100

/**
 * Maximum memory to use, sqrt(MAX_FACT) is a good choice.
 */
#define MAX_MEM 10

/**
 * How many values do we test?
 */
#define TEST_ITER 10

/**
 * Range of values to use for MATH tests.
 */
#define MATH_MAX 5


/**
 * Do some DLOG operations for testing.
 *
 * @param edc context for ECC operations
 */
static void
test_dlog(struct GNUNET_CRYPTO_EccDlogContext *edc)
{
  gcry_mpi_t fact;
  gcry_mpi_t n;
  gcry_ctx_t ctx;
  gcry_mpi_point_t q;
  gcry_mpi_point_t g;
  unsigned int i;
  int x;
  int iret;

  GNUNET_assert(0 == gcry_mpi_ec_new(&ctx, NULL, CURVE));
  g = gcry_mpi_ec_get_point("g", ctx, 0);
  GNUNET_assert(NULL != g);
  n = gcry_mpi_ec_get_mpi("n", ctx, 0);
  q = gcry_mpi_point_new(0);
  fact = gcry_mpi_new(0);
  for (i = 0; i < TEST_ITER; i++)
    {
      fprintf(stderr, ".");
      x = GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_WEAK,
                                   MAX_FACT);
      if (0 == GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_WEAK,
                                        2))
        {
          gcry_mpi_set_ui(fact, x);
          gcry_mpi_sub(fact, n, fact);
          x = -x;
        }
      else
        {
          gcry_mpi_set_ui(fact, x);
        }
      gcry_mpi_ec_mul(q, fact, g, ctx);
      if (x !=
          (iret = GNUNET_CRYPTO_ecc_dlog(edc,
                                         q)))
        {
          fprintf(stderr,
                  "DLOG failed for value %d (%d)\n",
                  x,
                  iret);
          GNUNET_assert(0);
        }
    }
  gcry_mpi_release(fact);
  gcry_mpi_release(n);
  gcry_mpi_point_release(g);
  gcry_mpi_point_release(q);
  gcry_ctx_release(ctx);
  fprintf(stderr, "\n");
}


/**
 * Do some arithmetic operations for testing.
 *
 * @param edc context for ECC operations
 */
static void
test_math(struct GNUNET_CRYPTO_EccDlogContext *edc)
{
  int i;
  int j;
  gcry_mpi_point_t ip;
  gcry_mpi_point_t jp;
  gcry_mpi_point_t r;
  gcry_mpi_point_t ir;
  gcry_mpi_point_t irj;
  gcry_mpi_point_t r_inv;
  gcry_mpi_point_t sum;

  for (i = -MATH_MAX; i < MATH_MAX; i++)
    {
      ip = GNUNET_CRYPTO_ecc_dexp(edc, i);
      for (j = -MATH_MAX; j < MATH_MAX; j++)
        {
          fprintf(stderr, ".");
          jp = GNUNET_CRYPTO_ecc_dexp(edc, j);
          GNUNET_CRYPTO_ecc_rnd(edc,
                                &r,
                                &r_inv);
          ir = GNUNET_CRYPTO_ecc_add(edc, ip, r);
          irj = GNUNET_CRYPTO_ecc_add(edc, ir, jp);
          sum = GNUNET_CRYPTO_ecc_add(edc, irj, r_inv);
          GNUNET_assert(i + j ==
                        GNUNET_CRYPTO_ecc_dlog(edc,
                                               sum));
          GNUNET_CRYPTO_ecc_free(jp);
          GNUNET_CRYPTO_ecc_free(ir);
          GNUNET_CRYPTO_ecc_free(irj);
          GNUNET_CRYPTO_ecc_free(r);
          GNUNET_CRYPTO_ecc_free(r_inv);
          GNUNET_CRYPTO_ecc_free(sum);
        }
      GNUNET_CRYPTO_ecc_free(ip);
    }
  fprintf(stderr, "\n");
}



int
main(int argc, char *argv[])
{
  struct GNUNET_CRYPTO_EccDlogContext *edc;

  if (!gcry_check_version("1.6.0"))
    {
      fprintf(stderr,
              _
                ("libgcrypt has not the expected version (version %s is required).\n"),
              "1.6.0");
      return 0;
    }
  if (getenv("GNUNET_GCRYPT_DEBUG"))
    gcry_control(GCRYCTL_SET_DEBUG_FLAGS, 1u, 0);
  GNUNET_log_setup("test-crypto-ecc-dlog",
                   "WARNING",
                   NULL);
  edc = GNUNET_CRYPTO_ecc_dlog_prepare(MAX_FACT,
                                       MAX_MEM);
  test_dlog(edc);
  test_math(edc);
  GNUNET_CRYPTO_ecc_dlog_release(edc);
  return 0;
}

/* end of test_crypto_ecc_dlog.c */