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@Cilyan
Last active Aug 29, 2021
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Pure Python implementation of FNV64 and a custom hash suitable for urls. The hash prepends a salt in from of the data, then computes the FNV64 hash and encode the data in base64. Remember however that the FNV64 is not a cryptographic hash.
#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2014 Cilyan Olowen <gaknar@gmail.com>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of the nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
import base64
import struct
def fnv64(data):
hash_ = 0xcbf29ce484222325
for b in data:
hash_ *= 0x100000001b3
hash_ &= 0xffffffffffffffff
hash_ ^= b
return hash_
def hash_dn(dn, salt):
# Turn dn into bytes with a salt, dn is expected to be ascii data
data = salt.encode("ascii") + dn.encode("ascii")
# Hash data
hash_ = fnv64(data)
# Pack hash (int) into bytes
bhash = struct.pack("<Q", hash_)
# Encode in base64. There is always a padding "=" at the end, because the
# hash is always 64bits long. We don't need it.
return base64.urlsafe_b64encode(bhash)[:-1].decode("ascii")
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