src/util/crypto_pow.c

   1 /*
   2      This file is part of GNUnet.
   3      Copyright (C) 2012, 2013, 2019 GNUnet e.V.
   4
   5      GNUnet is free software: you can redistribute it and/or modify it
   6      under the terms of the GNU Affero General Public License as published
   7      by the Free Software Foundation, either version 3 of the License,
   8      or (at your option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      Affero General Public License for more details.
  14
  15      You should have received a copy of the GNU Affero General Public License
  16      along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18      SPDX-License-Identifier: AGPL3.0-or-later
  19  */
  20 /**
  21  * @file util/crypto_pow.c
  22  * @brief proof-of-work hashing
  23  * @author Christian Grothoff
  24  * @author Bart Polot
  25  */
  26 #include "platform.h"
  27 #include "gnunet_crypto_lib.h"
  28 #include <gcrypt.h>
  29
  30 /* FIXME: change to 1 for #3795 / 0.12! */
  31 #define NEW_CRYPTO 0
  32
  33 /**
  34  * Calculate the 'proof-of-work' hash (an expensive hash).
  35  * We're using a non-standard formula to avoid issues with
  36  * ASICs appearing (see #3795).
  37  *
  38  * @param salt salt for the hash
  39  * @param buf data to hash
  40  * @param buf_len number of bytes in @a buf
  41  * @param result where to write the resulting hash
  42  */
  43 void
  44 GNUNET_CRYPTO_pow_hash (const char *salt,
  45                         const void *buf,
  46                         size_t buf_len,
  47                         struct GNUNET_HashCode *result)
  48 {
  49 #if NEW_CRYPTO
  50   struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
  51   struct GNUNET_CRYPTO_SymmetricSessionKey skey;
  52   char rbuf[buf_len];
  53
  54   GNUNET_break (0 == gcry_kdf_derive (buf,
  55                                       buf_len,
  56                                       GCRY_KDF_SCRYPT,
  57                                       1 /* subalgo */,
  58                                       salt,
  59                                       strlen (salt),
  60                                       2 /* iterations; keep cost of individual op small */,
  61                                       sizeof(skey),
  62                                       &skey));
  63   GNUNET_CRYPTO_symmetric_derive_iv (&iv,
  64                                      &skey,
  65                                      "gnunet-proof-of-work-iv",
  66                                      strlen ("gnunet-proof-of-work-iv"),
  67                                      salt,
  68                                      strlen (salt),
  69                                      NULL, 0);
  70   GNUNET_CRYPTO_symmetric_encrypt (buf,
  71                                    buf_len,
  72                                    &skey,
  73                                    &iv,
  74                                    &rbuf);
  75   GNUNET_break (0 == gcry_kdf_derive (rbuf,
  76                                       buf_len,
  77                                       GCRY_KDF_SCRYPT,
  78                                       1 /* subalgo */,
  79                                       salt,
  80                                       strlen (salt),
  81                                       2 /* iterations; keep cost of individual op small */,
  82                                       sizeof(struct GNUNET_HashCode),
  83                                       result));
  84 #else
  85   GNUNET_break (0 == gcry_kdf_derive (buf,
  86                                       buf_len,
  87                                       GCRY_KDF_SCRYPT,
  88                                       1 /* subalgo */,
  89                                       salt,
  90                                       strlen (salt),
  91                                       2 /* iterations; keep cost of individual op small */,
  92                                       sizeof(struct GNUNET_HashCode),
  93                                       result));
  94 #endif
  95 }
  96
  97
  98 /* end of crypto_pow.c */