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# -*- coding: ascii -*-
#
# Random/Fortuna/SHAd256.py : SHA_d-256 hash function implementation
#
# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
#
# ===================================================================
# The contents of this file are dedicated to the public domain. To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# ===================================================================
"""\
SHA_d-256 hash function implementation.
This module should comply with PEP 247.
"""
__revision__ = "$Id$"
__all__ = ['new', 'digest_size']
from Crypto.Util.python_compat import *
from binascii import b2a_hex
from Crypto.Hash import SHA256
assert SHA256.digest_size == 32
class _SHAd256(object):
"""SHA-256, doubled.
Returns SHA-256(SHA-256(data)).
"""
digest_size = SHA256.digest_size
_internal = object()
def __init__(self, internal_api_check, sha256_hash_obj):
if internal_api_check is not self._internal:
raise AssertionError("Do not instantiate this class directly. Use %s.new()" % (__name__,))
self._h = sha256_hash_obj
# PEP 247 "copy" method
def copy(self):
"""Return a copy of this hashing object"""
return _SHAd256(SHAd256._internal, self._h.copy())
# PEP 247 "digest" method
def digest(self):
"""Return the hash value of this object as a binary string"""
retval = SHA256.new(self._h.digest()).digest()
assert len(retval) == 32
return retval
# PEP 247 "hexdigest" method
def hexdigest(self):
"""Return the hash value of this object as a (lowercase) hexadecimal string"""
retval = b2a_hex(self.digest())
assert len(retval) == 64
return retval
# PEP 247 "update" method
def update(self, data):
self._h.update(data)
# PEP 247 module-level "digest_size" variable
digest_size = _SHAd256.digest_size
# PEP 247 module-level "new" function
def new(data=""):
"""Return a new SHAd256 hashing object"""
return _SHAd256(_SHAd256._internal, SHA256.new(data))
# vim:set ts=4 sw=4 sts=4 expandtab:
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