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MD2.py

# ===================================================================
#
# Copyright (c) 2014, Legrandin <helderijs@gmail.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
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#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in
#    the documentation and/or other materials provided with the
#    distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# ===================================================================

from Crypto.Util.py3compat import bord

from Crypto.Util._raw_api import (load_pycryptodome_raw_lib,
                                  VoidPointer, SmartPointer,
                                  create_string_buffer,
                                  get_raw_buffer, c_size_t,
                                  c_uint8_ptr)

_raw_md2_lib = load_pycryptodome_raw_lib(
                        "Crypto.Hash._MD2",
                        """
                        int md2_init(void **shaState);
                        int md2_destroy(void *shaState);
                        int md2_update(void *hs,
                                          const uint8_t *buf,
                                          size_t len);
                        int md2_digest(const void *shaState,
                                          uint8_t digest[20]);
                        int md2_copy(const void *src, void *dst);
                        """)

class MD2Hash(object):
    """An MD2 hash object.
    Do not instantiate directly. Use the :func:`new` function.

:ivar oid: ASN.1 Object ID
    :vartype oid: string

:ivar block_size: the size in bytes of the internal message block,
                      input to the compression function
    :vartype block_size: integer

:ivar digest_size: the size in bytes of the resulting hash
    :vartype digest_size: integer
    """

# The size of the resulting hash in bytes.
    digest_size = 16
    # The internal block size of the hash algorithm in bytes.
    block_size = 16
    # ASN.1 Object ID
    oid = "1.2.840.113549.2.2"

def __init__(self, data=None):
        state = VoidPointer()
        result = _raw_md2_lib.md2_init(state.address_of())
        if result:
            raise ValueError("Error %d while instantiating MD2"
                             % result)
        self._state = SmartPointer(state.get(),
                                   _raw_md2_lib.md2_destroy)
        if data:
            self.update(data)

def update(self, data):
        """Continue hashing of a message by consuming the next chunk of data.

Args:
            data (byte string/byte array/memoryview): The next chunk of the message being hashed.
        """

result = _raw_md2_lib.md2_update(self._state.get(),
                                         c_uint8_ptr(data),
                                         c_size_t(len(data)))
        if result:
            raise ValueError("Error %d while instantiating MD2"
                             % result)

def digest(self):
        """Return the **binary** (non-printable) digest of the message that has been hashed so far.

:return: The hash digest, computed over the data processed so far.
                 Binary form.
        :rtype: byte string
        """

bfr = create_string_buffer(self.digest_size)
        result = _raw_md2_lib.md2_digest(self._state.get(),
                                         bfr)
        if result:
            raise ValueError("Error %d while instantiating MD2"
                             % result)

return get_raw_buffer(bfr)

def hexdigest(self):
        """Return the **printable** digest of the message that has been hashed so far.

:return: The hash digest, computed over the data processed so far.
                 Hexadecimal encoded.
        :rtype: string
        """

return "".join(["%02x" % bord(x) for x in self.digest()])

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
        """

clone = MD2Hash()
        result = _raw_md2_lib.md2_copy(self._state.get(),
                                       clone._state.get())
        if result:
            raise ValueError("Error %d while copying MD2" % result)
        return clone

def new(self, data=None):
        return MD2Hash(data)

def new(data=None):
    """Create a new hash object.

:parameter data:
        Optional. The very first chunk of the message to hash.
        It is equivalent to an early call to :meth:`MD2Hash.update`.
    :type data: bytes/bytearray/memoryview

:Return: A :class:`MD2Hash` hash object
    """

return MD2Hash().new(data)

# The size of the resulting hash in bytes.
digest_size = MD2Hash.digest_size

# The internal block size of the hash algorithm in bytes.
block_size = MD2Hash.block_size

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