1 # -*- coding: UTF-8 -*-

     2 # Copyright (c) 2010, Pascal Volk

     3 # See COPYING for distribution information.

     4 

     5 """

     6     VirtualMailManager.pycompat.hashlib

     7 

     8     VirtualMailManager's minimal hashlib emulation for Python 2.4

     9 

    10     hashlib.md5(...), hashlib.sha1(...), hashlib.new('md5', ...) and

    11     hashlib.new('sha1', ...) will work always.

    12 

    13     When the PyCrypto module <http://www.pycrypto.org/> could be found in

    14     sys.path hashlib.new('md4', ...) will also work.

    15 

    16     With PyCrypto >= 2.1.0alpha1 hashlib.new('sha256', ...) and

    17     hashlib.sha256(...) becomes functional.

    18 """

    19 

    20 

    21 import md5 as _md5

    22 import sha as _sha1

    23 

    24 try:

    25     import Crypto

    26 except ImportError:

    27     _md4 = None

    28     SHA256 = None

    29 else:

    30     from Crypto.Hash import MD4 as _md4

    31     if hasattr(Crypto, 'version_info'):  # <- Available since v2.1.0alpha1

    32         from Crypto.Hash import SHA256   # SHA256 works since v2.1.0alpha1

    33         sha256 = SHA256.new

    34     else:

    35         SHA256 = None

    36     del Crypto

    37 

    38 

    39 compat = 0x01

    40 md5 = _md5.new

    41 sha1 = _sha1.new

    42 

    43 

    44 def new(name, string=''):

    45     """Return a new hashing object using the named algorithm, optionally

    46     initialized with the provided string.

    47     """

    48     if name in ('md5', 'MD5'):

    49         return _md5.new(string)

    50     if name in ('sha1', 'SHA1'):

    51         return _sha1.new(string)

    52     if not _md4:

    53         raise ValueError('unsupported hash type')

    54     if name in ('md4', 'MD4'):

    55         return _md4.new(string)

    56     if name in ('sha256', 'SHA256') and SHA256:

    57         return SHA256.new(string)

    58     raise ValueError('unsupported hash type')