#!/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
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#  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")