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3 Copyright (C) 2012, 2013, 2019 GNUnet e.V.
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.
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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.
15 You should have received a copy of the GNU Affero General Public License
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18 SPDX-License-Identifier: AGPL3.0-or-later
21 * @file util/crypto_pow.c
22 * @brief proof-of-work hashing
23 * @author Christian Grothoff
27 #include "gnunet_crypto_lib.h"
32 * Calculate the 'proof-of-work' hash (an expensive hash).
33 * We're using a non-standard formula to avoid issues with
34 * ASICs appearing (see #3795).
36 * @param salt salt for the hash
37 * @param buf data to hash
38 * @param buf_len number of bytes in @a buf
39 * @param result where to write the resulting hash
42 GNUNET_CRYPTO_pow_hash (const char *salt,
45 struct GNUNET_HashCode *result)
47 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
48 struct GNUNET_CRYPTO_SymmetricSessionKey skey;
51 GNUNET_break (0 == gcry_kdf_derive (buf,
57 2 /* iterations; keep cost of individual op small */,
60 GNUNET_CRYPTO_symmetric_derive_iv (&iv,
62 "gnunet-proof-of-work-iv",
63 strlen ("gnunet-proof-of-work-iv"),
67 GNUNET_CRYPTO_symmetric_encrypt (buf,
72 GNUNET_break (0 == gcry_kdf_derive (rbuf,
78 2 /* iterations; keep cost of individual op small */,
79 sizeof(struct GNUNET_HashCode),
84 /* end of crypto_pow.c */