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# Copyright (C) 2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""Hashing backwards compatibility wrapper"""
import sys
_hashes = None
def _need_later_python(alg):
def func(*args, **kwargs):
raise NotImplementedError("TSIG algorithm " + alg +
" requires Python 2.5.2 or later")
return func
def _setup():
global _hashes
_hashes = {}
try:
import hashlib
_hashes['MD5'] = hashlib.md5
_hashes['SHA1'] = hashlib.sha1
_hashes['SHA224'] = hashlib.sha224
_hashes['SHA256'] = hashlib.sha256
if sys.hexversion >= 0x02050200:
_hashes['SHA384'] = hashlib.sha384
_hashes['SHA512'] = hashlib.sha512
else:
_hashes['SHA384'] = _need_later_python('SHA384')
_hashes['SHA512'] = _need_later_python('SHA512')
if sys.hexversion < 0x02050000:
# hashlib doesn't conform to PEP 247: API for
# Cryptographic Hash Functions, which hmac before python
# 2.5 requires, so add the necessary items.
class HashlibWrapper:
def __init__(self, basehash):
self.basehash = basehash
self.digest_size = self.basehash().digest_size
def new(self, *args, **kwargs):
return self.basehash(*args, **kwargs)
for name in _hashes:
_hashes[name] = HashlibWrapper(_hashes[name])
except ImportError:
import md5, sha
_hashes['MD5'] = md5
_hashes['SHA1'] = sha
def get(algorithm):
if _hashes is None:
_setup()
return _hashes[algorithm.upper()]
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