basic functionalty

modules/Crypto/Random/Fortuna/SHAd256.py

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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']
+
+import sys
+if sys.version_info[0] == 2 and sys.version_info[1] == 1:
+    from Crypto.Util.py21compat import *
+from Crypto.Util.py3compat 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
+        if sys.version_info[0] == 2:
+            return retval
+        else:
+            return retval.decode()
+
+    # 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=None):
+    """Return a new SHAd256 hashing object"""
+    if not data:
+        data=b("")
+    sha = _SHAd256(_SHAd256._internal, SHA256.new(data))
+    sha.new = globals()['new']
+    return sha
+
+# vim:set ts=4 sw=4 sts=4 expandtab: