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