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| 1 # -*- coding: ascii -*- |
| 2 # |
| 3 # Random/Fortuna/SHAd256.py : SHA_d-256 hash function implementation |
| 4 # |
| 5 # Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net> |
| 6 # |
| 7 # =================================================================== |
| 8 # The contents of this file are dedicated to the public domain. To |
| 9 # the extent that dedication to the public domain is not available, |
| 10 # everyone is granted a worldwide, perpetual, royalty-free, |
| 11 # non-exclusive license to exercise all rights associated with the |
| 12 # contents of this file for any purpose whatsoever. |
| 13 # No rights are reserved. |
| 14 # |
| 15 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 16 # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 17 # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| 18 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
| 19 # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
| 20 # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| 21 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 22 # SOFTWARE. |
| 23 # =================================================================== |
| 24 |
| 25 """\ |
| 26 SHA_d-256 hash function implementation. |
| 27 |
| 28 This module should comply with PEP 247. |
| 29 """ |
| 30 |
| 31 __revision__ = "$Id$" |
| 32 __all__ = ['new', 'digest_size'] |
| 33 |
| 34 import sys |
| 35 if sys.version_info[0] == 2 and sys.version_info[1] == 1: |
| 36 from Crypto.Util.py21compat import * |
| 37 from Crypto.Util.py3compat import * |
| 38 |
| 39 from binascii import b2a_hex |
| 40 |
| 41 from Crypto.Hash import SHA256 |
| 42 |
| 43 assert SHA256.digest_size == 32 |
| 44 |
| 45 class _SHAd256(object): |
| 46 """SHA-256, doubled. |
| 47 |
| 48 Returns SHA-256(SHA-256(data)). |
| 49 """ |
| 50 |
| 51 digest_size = SHA256.digest_size |
| 52 |
| 53 _internal = object() |
| 54 |
| 55 def __init__(self, internal_api_check, sha256_hash_obj): |
| 56 if internal_api_check is not self._internal: |
| 57 raise AssertionError("Do not instantiate this class directly. Use %
s.new()" % (__name__,)) |
| 58 self._h = sha256_hash_obj |
| 59 |
| 60 # PEP 247 "copy" method |
| 61 def copy(self): |
| 62 """Return a copy of this hashing object""" |
| 63 return _SHAd256(SHAd256._internal, self._h.copy()) |
| 64 |
| 65 # PEP 247 "digest" method |
| 66 def digest(self): |
| 67 """Return the hash value of this object as a binary string""" |
| 68 retval = SHA256.new(self._h.digest()).digest() |
| 69 assert len(retval) == 32 |
| 70 return retval |
| 71 |
| 72 # PEP 247 "hexdigest" method |
| 73 def hexdigest(self): |
| 74 """Return the hash value of this object as a (lowercase) hexadecimal str
ing""" |
| 75 retval = b2a_hex(self.digest()) |
| 76 assert len(retval) == 64 |
| 77 if sys.version_info[0] == 2: |
| 78 return retval |
| 79 else: |
| 80 return retval.decode() |
| 81 |
| 82 # PEP 247 "update" method |
| 83 def update(self, data): |
| 84 self._h.update(data) |
| 85 |
| 86 # PEP 247 module-level "digest_size" variable |
| 87 digest_size = _SHAd256.digest_size |
| 88 |
| 89 # PEP 247 module-level "new" function |
| 90 def new(data=None): |
| 91 """Return a new SHAd256 hashing object""" |
| 92 if not data: |
| 93 data=b("") |
| 94 sha = _SHAd256(_SHAd256._internal, SHA256.new(data)) |
| 95 sha.new = globals()['new'] |
| 96 return sha |
| 97 |
| 98 # vim:set ts=4 sw=4 sts=4 expandtab: |
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