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# -*- coding: utf-8 -*-
#
# ===================================================================
# 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.
# ===================================================================
from binascii import hexlify
class HashAlgo:
"""A generic class for an abstract cryptographic hash algorithm.
:undocumented: block_size
"""
#: The size of the resulting hash in bytes.
digest_size = None
#: The internal block size of the hash algorithm in bytes.
block_size = None
def __init__(self, hashFactory, data=None):
"""Initialize the hash object.
:Parameters:
hashFactory : callable
An object that will generate the actual hash implementation.
*hashFactory* must have a *new()* method, or must be directly
callable.
data : byte string
The very first chunk of the message to hash.
It is equivalent to an early call to `update()`.
"""
if hasattr(hashFactory, 'new'):
self._hash = hashFactory.new()
else:
self._hash = hashFactory()
if data:
self.update(data)
def update(self, data):
"""Continue hashing of a message by consuming the next chunk of data.
Repeated calls are equivalent to a single call with the concatenation
of all the arguments. In other words:
>>> m.update(a); m.update(b)
is equivalent to:
>>> m.update(a+b)
:Parameters:
data : byte string
The next chunk of the message being hashed.
"""
return self._hash.update(data)
def digest(self):
"""Return the **binary** (non-printable) digest of the message that has been hashed so far.
This method does not change the state of the hash object.
You can continue updating the object after calling this function.
:Return: A byte string of `digest_size` bytes. It may contain non-ASCII
characters, including null bytes.
"""
return self._hash.digest()
def hexdigest(self):
"""Return the **printable** digest of the message that has been hashed so far.
This method does not change the state of the hash object.
:Return: A string of 2* `digest_size` characters. It contains only
hexadecimal ASCII digits.
"""
return self._hash.hexdigest()
def copy(self):
"""Return a copy ("clone") of the hash object.
The copy will have the same internal state as the original hash
object.
This can be used to efficiently compute the digests of strings that
share a common initial substring.
:Return: A hash object of the same type
"""
return self._hash.copy()
def new(self, data=None):
"""Return a fresh instance of the hash object.
Unlike the `copy` method, the internal state of the object is empty.
:Parameters:
data : byte string
The next chunk of the message being hashed.
:Return: A hash object of the same type
"""
pass
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