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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))
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