116 lines
3.9 KiB
Python
116 lines
3.9 KiB
Python
# -*- coding: utf-8 -*-
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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from binascii import hexlify
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class HashAlgo:
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"""A generic class for an abstract cryptographic hash algorithm.
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:undocumented: block_size
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"""
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#: The size of the resulting hash in bytes.
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digest_size = None
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#: The internal block size of the hash algorithm in bytes.
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block_size = None
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def __init__(self, hashFactory, data=None):
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"""Initialize the hash object.
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:Parameters:
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hashFactory : callable
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An object that will generate the actual hash implementation.
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*hashFactory* must have a *new()* method, or must be directly
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callable.
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data : byte string
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The very first chunk of the message to hash.
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It is equivalent to an early call to `update()`.
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"""
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if hasattr(hashFactory, 'new'):
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self._hash = hashFactory.new()
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else:
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self._hash = hashFactory()
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if data:
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self.update(data)
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def update(self, data):
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"""Continue hashing of a message by consuming the next chunk of data.
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Repeated calls are equivalent to a single call with the concatenation
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of all the arguments. In other words:
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>>> m.update(a); m.update(b)
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is equivalent to:
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>>> m.update(a+b)
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:Parameters:
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data : byte string
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The next chunk of the message being hashed.
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"""
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return self._hash.update(data)
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def digest(self):
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"""Return the **binary** (non-printable) digest of the message that has been hashed so far.
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This method does not change the state of the hash object.
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You can continue updating the object after calling this function.
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:Return: A byte string of `digest_size` bytes. It may contain non-ASCII
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characters, including null bytes.
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"""
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return self._hash.digest()
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def hexdigest(self):
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"""Return the **printable** digest of the message that has been hashed so far.
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This method does not change the state of the hash object.
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:Return: A string of 2* `digest_size` characters. It contains only
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hexadecimal ASCII digits.
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"""
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return self._hash.hexdigest()
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def copy(self):
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"""Return a copy ("clone") of the hash object.
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The copy will have the same internal state as the original hash
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object.
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This can be used to efficiently compute the digests of strings that
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share a common initial substring.
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:Return: A hash object of the same type
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"""
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return self._hash.copy()
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def new(self, data=None):
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"""Return a fresh instance of the hash object.
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Unlike the `copy` method, the internal state of the object is empty.
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:Parameters:
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data : byte string
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The next chunk of the message being hashed.
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:Return: A hash object of the same type
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"""
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pass
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