2013-10-02 12:59:40 -06:00
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#!/usr/bin/env python
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# vim:ts=4:sw=4:softtabstop=4:smarttab:expandtab
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# implement just enough of des from openssl to make erdr2pml.py happy
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def load_libcrypto():
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from ctypes import CDLL, POINTER, c_void_p, c_char_p, c_char, c_int, c_long, \
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Structure, c_ulong, create_string_buffer, cast
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from ctypes.util import find_library
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import sys
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if sys.platform.startswith('win'):
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libcrypto = find_library('libeay32')
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else:
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libcrypto = find_library('crypto')
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if libcrypto is None:
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return None
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libcrypto = CDLL(libcrypto)
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# typedef struct DES_ks
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# {
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# union
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# {
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# DES_cblock cblock;
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# /* make sure things are correct size on machines with
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# * 8 byte longs */
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# DES_LONG deslong[2];
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# } ks[16];
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# } DES_key_schedule;
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# just create a big enough place to hold everything
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# it will have alignment of structure so we should be okay (16 byte aligned?)
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class DES_KEY_SCHEDULE(Structure):
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_fields_ = [('DES_cblock1', c_char * 16),
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('DES_cblock2', c_char * 16),
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('DES_cblock3', c_char * 16),
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('DES_cblock4', c_char * 16),
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('DES_cblock5', c_char * 16),
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('DES_cblock6', c_char * 16),
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('DES_cblock7', c_char * 16),
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('DES_cblock8', c_char * 16),
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('DES_cblock9', c_char * 16),
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('DES_cblock10', c_char * 16),
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('DES_cblock11', c_char * 16),
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('DES_cblock12', c_char * 16),
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('DES_cblock13', c_char * 16),
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('DES_cblock14', c_char * 16),
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('DES_cblock15', c_char * 16),
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('DES_cblock16', c_char * 16)]
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DES_KEY_SCHEDULE_p = POINTER(DES_KEY_SCHEDULE)
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def F(restype, name, argtypes):
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func = getattr(libcrypto, name)
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func.restype = restype
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func.argtypes = argtypes
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return func
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DES_set_key = F(None, 'DES_set_key',[c_char_p, DES_KEY_SCHEDULE_p])
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DES_ecb_encrypt = F(None, 'DES_ecb_encrypt',[c_char_p, c_char_p, DES_KEY_SCHEDULE_p, c_int])
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class DES(object):
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def __init__(self, key):
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if len(key) != 8 :
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raise Exception('DES improper key used')
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return
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self.key = key
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self.keyschedule = DES_KEY_SCHEDULE()
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DES_set_key(self.key, self.keyschedule)
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def desdecrypt(self, data):
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ob = create_string_buffer(len(data))
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DES_ecb_encrypt(data, ob, self.keyschedule, 0)
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return ob.raw
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def decrypt(self, data):
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if not data:
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return ''
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i = 0
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result = []
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while i < len(data):
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block = data[i:i+8]
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processed_block = self.desdecrypt(block)
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result.append(processed_block)
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i += 8
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return ''.join(result)
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return DES
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