/*
     This file is part of GNUnet.
     Copyright (C) 2014 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_paillier.c
 * @brief testcase paillier crypto
 * @author Christian Fuchs
 * @author Florian Dold
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include <gcrypt.h>


static int
test_crypto()
{
  gcry_mpi_t plaintext;
  gcry_mpi_t plaintext_result;
  struct GNUNET_CRYPTO_PaillierCiphertext ciphertext;
  struct GNUNET_CRYPTO_PaillierPublicKey public_key;
  struct GNUNET_CRYPTO_PaillierPrivateKey private_key;
  int ret = 0;

  GNUNET_CRYPTO_paillier_create(&public_key,
                                &private_key);
  GNUNET_assert(NULL != (plaintext = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (plaintext_result = gcry_mpi_new(0)));
  gcry_mpi_randomize(plaintext,
                     GNUNET_CRYPTO_PAILLIER_BITS / 2,
                     GCRY_WEAK_RANDOM);

  GNUNET_CRYPTO_paillier_encrypt(&public_key,
                                 plaintext,
                                 0 /* 0 hom ops */,
                                 &ciphertext);
  GNUNET_CRYPTO_paillier_decrypt(&private_key,
                                 &public_key,
                                 &ciphertext,
                                 plaintext_result);
  if (0 != gcry_mpi_cmp(plaintext,
                        plaintext_result))
    {
      fprintf(stderr,
              "Paillier decryption failed with plaintext of size %u\n",
              gcry_mpi_get_nbits(plaintext));
      gcry_log_debugmpi("\n",
                        plaintext);
      gcry_log_debugmpi("\n",
                        plaintext_result);
      ret = 1;
    }
  gcry_mpi_release(plaintext);
  gcry_mpi_release(plaintext_result);
  return ret;
}


static int
test_hom_simple(unsigned int a,
                unsigned int b)
{
  gcry_mpi_t m1;
  gcry_mpi_t m2;
  gcry_mpi_t result;
  gcry_mpi_t hom_result;
  struct GNUNET_CRYPTO_PaillierCiphertext c1;
  struct GNUNET_CRYPTO_PaillierCiphertext c2;
  struct GNUNET_CRYPTO_PaillierCiphertext c_result;
  struct GNUNET_CRYPTO_PaillierPublicKey public_key;
  struct GNUNET_CRYPTO_PaillierPrivateKey private_key;
  int ret = 0;

  GNUNET_CRYPTO_paillier_create(&public_key,
                                &private_key);

  GNUNET_assert(NULL != (m1 = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (m2 = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (result = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (hom_result = gcry_mpi_new(0)));
  m1 = gcry_mpi_set_ui(m1, a);
  m2 = gcry_mpi_set_ui(m2, b);
  gcry_mpi_add(result,
               m1,
               m2);
  GNUNET_CRYPTO_paillier_encrypt(&public_key,
                                 m1,
                                 2,
                                 &c1);
  GNUNET_CRYPTO_paillier_encrypt(&public_key,
                                 m2,
                                 2,
                                 &c2);
  GNUNET_CRYPTO_paillier_hom_add(&public_key,
                                 &c1,
                                 &c2,
                                 &c_result);
  GNUNET_CRYPTO_paillier_decrypt(&private_key,
                                 &public_key,
                                 &c_result,
                                 hom_result);
  if (0 != gcry_mpi_cmp(result, hom_result))
    {
      fprintf(stderr,
              "GNUNET_CRYPTO_paillier failed simple math!\n");
      gcry_log_debugmpi("got ", hom_result);
      gcry_log_debugmpi("wanted ", result);
      ret = 1;
    }
  gcry_mpi_release(m1);
  gcry_mpi_release(m2);
  gcry_mpi_release(result);
  gcry_mpi_release(hom_result);
  return ret;
}


static int
test_hom()
{
  int ret;
  gcry_mpi_t m1;
  gcry_mpi_t m2;
  gcry_mpi_t result;
  gcry_mpi_t hom_result;
  struct GNUNET_CRYPTO_PaillierCiphertext c1;
  struct GNUNET_CRYPTO_PaillierCiphertext c2;
  struct GNUNET_CRYPTO_PaillierCiphertext c_result;
  struct GNUNET_CRYPTO_PaillierPublicKey public_key;
  struct GNUNET_CRYPTO_PaillierPrivateKey private_key;

  GNUNET_CRYPTO_paillier_create(&public_key,
                                &private_key);

  GNUNET_assert(NULL != (m1 = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (m2 = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (result = gcry_mpi_new(0)));
  GNUNET_assert(NULL != (hom_result = gcry_mpi_new(0)));
  m1 = gcry_mpi_set_ui(m1, 1);
  /* m1 = m1 * 2 ^ (GCPB - 3) */
  gcry_mpi_mul_2exp(m1,
                    m1,
                    GNUNET_CRYPTO_PAILLIER_BITS - 3);
  m2 = gcry_mpi_set_ui(m2, 15);
  /* m1 = m1 * 2 ^ (GCPB / 2) */
  gcry_mpi_mul_2exp(m2,
                    m2,
                    GNUNET_CRYPTO_PAILLIER_BITS / 2);
  gcry_mpi_add(result,
               m1,
               m2);

  if (1 != (ret = GNUNET_CRYPTO_paillier_encrypt(&public_key,
                                                 m1,
                                                 2,
                                                 &c1)))
    {
      fprintf(stderr,
              "GNUNET_CRYPTO_paillier_encrypt 1 failed, should return 1 allowed operation, got %d!\n",
              ret);
      ret = 1;
      goto out;
    }
  if (2 != (ret = GNUNET_CRYPTO_paillier_encrypt(&public_key,
                                                 m2,
                                                 2,
                                                 &c2)))
    {
      fprintf(stderr,
              "GNUNET_CRYPTO_paillier_encrypt 2 failed, should return 2 allowed operation, got %d!\n",
              ret);
      ret = 1;
      goto out;
    }

  if (0 != (ret = GNUNET_CRYPTO_paillier_hom_add(&public_key,
                                                 &c1,
                                                 &c2,
                                                 &c_result)))
    {
      fprintf(stderr,
              "GNUNET_CRYPTO_paillier_hom_add failed, expected 0 remaining operations, got %d!\n",
              ret);
      ret = 1;
      goto out;
    }

  GNUNET_CRYPTO_paillier_decrypt(&private_key,
                                 &public_key,
                                 &c_result,
                                 hom_result);

  if (0 != gcry_mpi_cmp(result, hom_result))
    {
      fprintf(stderr,
              "GNUNET_CRYPTO_paillier miscalculated with large numbers!\n");
      gcry_log_debugmpi("got", hom_result);
      gcry_log_debugmpi("wanted", result);
      ret = 1;
    }
out:
  gcry_mpi_release(m1);
  gcry_mpi_release(m2);
  gcry_mpi_release(result);
  gcry_mpi_release(hom_result);
  return ret;
}


int
main(int argc,
     char *argv[])
{
  int ret;

  ret = test_crypto();
  if (0 != ret)
    return ret;
  ret = test_hom_simple(2, 4);
  if (0 != ret)
    return ret;
  ret = test_hom_simple(13, 17);
  if (0 != ret)
    return ret;
  ret = test_hom();
  return ret;
}

/* end of test_crypto_paillier.c */