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 buf data to hash
  39  * @param buf_len number of bytes in @a buf
  40  * @param result where to write the resulting hash
  41  */
  42 void
  43 GNUNET_CRYPTO_pow_hash (const void *buf, size_t buf_len, struct
  44                         GNUNET_HashCode *result)
  45 {
  46 #if NEW_CRYPTO
  47   struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
  48   struct GNUNET_CRYPTO_SymmetricSessionKey skey;
  49   char rbuf[buf_len];
  50
  51   GNUNET_break (0 == gcry_kdf_derive (buf,
  52                                       buf_len,
  53                                       GCRY_KDF_SCRYPT,
  54                                       1 /* subalgo */,
  55                                       "gnunet-proof-of-work-1",
  56                                       strlen ("gnunet-proof-of-work-1"),
  57                                       2 /* iterations; keep cost of individual op small */,
  58                                       sizeof(skey),
  59                                       &skey));
  60   GNUNET_CRYPTO_symmetric_derive_iv (&iv,
  61                                      &skey,
  62                                      "gnunet-proof-of-work-iv",
  63                                      strlen ("gnunet-proof-of-work-iv"),
  64                                      NULL, 0);
  65   GNUNET_CRYPTO_symmetric_encrypt (buf,
  66                                    buf_len,
  67                                    &skey,
  68                                    &iv,
  69                                    &rbuf);
  70   GNUNET_break (0 == gcry_kdf_derive (rbuf,
  71                                       buf_len,
  72                                       GCRY_KDF_SCRYPT,
  73                                       1 /* subalgo */,
  74                                       "gnunet-proof-of-work-2",
  75                                       strlen ("gnunet-proof-of-work-2"),
  76                                       2 /* iterations; keep cost of individual op small */,
  77                                       sizeof(struct GNUNET_HashCode),
  78                                       result));
  79 #else
  80   GNUNET_break (0 == gcry_kdf_derive (buf,
  81                                       buf_len,
  82                                       GCRY_KDF_SCRYPT,
  83                                       1 /* subalgo */,
  84                                       "gnunet-proof-of-work",
  85                                       strlen ("gnunet-proof-of-work"),
  86                                       2 /* iterations; keep cost of individual op small */,
  87                                       sizeof(struct GNUNET_HashCode),
  88                                       result));
  89 #endif
  90 }
  91
  92
  93 /* end of crypto_pow.c */