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/*
This file is part of GNUnet.
Copyright (C) 2012, 2013, 2019 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/crypto_pow.c
* @brief proof-of-work hashing
* @author Christian Grothoff
* @author Bart Polot
*/
#include "platform.h"
#include "gnunet_crypto_lib.h"
#include <gcrypt.h>
/* FIXME: change to 1 for #3795 / 0.12! */
#define NEW_CRYPTO 0
/**
* Calculate the 'proof-of-work' hash (an expensive hash).
* We're using a non-standard formula to avoid issues with
* ASICs appearing (see #3795).
*
* @param buf data to hash
* @param buf_len number of bytes in @a buf
* @param result where to write the resulting hash
*/
void
GNUNET_CRYPTO_pow_hash (const void *buf, size_t buf_len, struct
GNUNET_HashCode *result)
{
#if NEW_CRYPTO
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
struct GNUNET_CRYPTO_SymmetricSessionKey skey;
char rbuf[buf_len];
GNUNET_break (0 == gcry_kdf_derive (buf,
buf_len,
GCRY_KDF_SCRYPT,
1 /* subalgo */,
"gnunet-proof-of-work-1",
strlen ("gnunet-proof-of-work-1"),
2 /* iterations; keep cost of individual op small */,
sizeof(skey),
&skey));
GNUNET_CRYPTO_symmetric_derive_iv (&iv,
&skey,
"gnunet-proof-of-work-iv",
strlen ("gnunet-proof-of-work-iv"),
NULL, 0);
GNUNET_CRYPTO_symmetric_encrypt (buf,
buf_len,
&skey,
&iv,
&rbuf);
GNUNET_break (0 == gcry_kdf_derive (rbuf,
buf_len,
GCRY_KDF_SCRYPT,
1 /* subalgo */,
"gnunet-proof-of-work-2",
strlen ("gnunet-proof-of-work-2"),
2 /* iterations; keep cost of individual op small */,
sizeof(struct GNUNET_HashCode),
result));
#else
GNUNET_break (0 == gcry_kdf_derive (buf,
buf_len,
GCRY_KDF_SCRYPT,
1 /* subalgo */,
"gnunet-proof-of-work",
strlen ("gnunet-proof-of-work"),
2 /* iterations; keep cost of individual op small */,
sizeof(struct GNUNET_HashCode),
result));
#endif
}
/* end of crypto_pow.c */
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