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-rw-r--r--src/util/crypto_pow.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/src/util/crypto_pow.c b/src/util/crypto_pow.c
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+++ b/src/util/crypto_pow.c
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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>
+
+
+/**
+ * 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)
+{
+ 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));
+}
+
+
+/* end of crypto_pow.c */