服务器之家

服务器之家 > 正文

python实现的DES加密算法和3DES加密算法实例

时间:2020-07-12 11:25     来源/作者:xm1331305

本文实例讲述了python实现的DES加密算法和3DES加密算法。分享给大家供大家参考。具体实现方法如下:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
#############################################################################
#         Documentation          #
#############################################################################
# Author:  Todd Whiteman
# Date:   16th March, 2009
# Verion:  2.0.0
# License: Public Domain - free to do as you wish
# Homepage: http://twhiteman.netfirms.com/des.html
#
# This is a pure python implementation of the DES encryption algorithm.
# It's pure python to avoid portability issues, since most DES
# implementations are programmed in C (for performance reasons).
#
# Triple DES class is also implemented, utilising the DES base. Triple DES
# is either DES-EDE3 with a 24 byte key, or DES-EDE2 with a 16 byte key.
#
# See the README.txt that should come with this python module for the
# implementation methods used.
#
# Thanks to:
# * David Broadwell for ideas, comments and suggestions.
# * Mario Wolff for pointing out and debugging some triple des CBC errors.
# * Santiago Palladino for providing the PKCS5 padding technique.
# * Shaya for correcting the PAD_PKCS5 triple des CBC errors.
#
"""A pure python implementation of the DES and TRIPLE DES encryption algorithms.
Class initialization
--------------------
pyDes.des(key, [mode], [IV], [pad], [padmode])
pyDes.triple_des(key, [mode], [IV], [pad], [padmode])
key   -> Bytes containing the encryption key. 8 bytes for DES, 16 or 24 bytes
    for Triple DES
mode  -> Optional argument for encryption type, can be either
    pyDes.ECB (Electronic Code Book) or pyDes.CBC (Cypher Block Chaining)
IV   -> Optional Initial Value bytes, must be supplied if using CBC mode.
    Length must be 8 bytes.
pad   -> Optional argument, set the pad character (PAD_NORMAL) to use during
    all encrypt/decrpt operations done with this instance.
padmode -> Optional argument, set the padding mode (PAD_NORMAL or PAD_PKCS5)
    to use during all encrypt/decrpt operations done with this instance.
I recommend to use PAD_PKCS5 padding, as then you never need to worry about any
padding issues, as the padding can be removed unambiguously upon decrypting
data that was encrypted using PAD_PKCS5 padmode.
Common methods
--------------
encrypt(data, [pad], [padmode])
decrypt(data, [pad], [padmode])
data  -> Bytes to be encrypted/decrypted
pad   -> Optional argument. Only when using padmode of PAD_NORMAL. For
    encryption, adds this characters to the end of the data block when
    data is not a multiple of 8 bytes. For decryption, will remove the
    trailing characters that match this pad character from the last 8
    bytes of the unencrypted data block.
padmode -> Optional argument, set the padding mode, must be one of PAD_NORMAL
    or PAD_PKCS5). Defaults to PAD_NORMAL.
 
Example
-------
from pyDes import *
data = "Please encrypt my data"
k = des("DESCRYPT", CBC, "\0\0\0\0\0\0\0\0", pad=None, padmode=PAD_PKCS5)
# For Python3, you'll need to use bytes, i.e.:
#  data = b"Please encrypt my data"
#  k = des(b"DESCRYPT", CBC, b"\0\0\0\0\0\0\0\0", pad=None, padmode=PAD_PKCS5)
d = k.encrypt(data)
print "Encrypted: %r" % d
print "Decrypted: %r" % k.decrypt(d)
assert k.decrypt(d, padmode=PAD_PKCS5) == data
 
See the module source (pyDes.py) for more examples of use.
You can also run the pyDes.py file without and arguments to see a simple test.
Note: This code was not written for high-end systems needing a fast
   implementation, but rather a handy portable solution with small usage.
"""
import sys
# _pythonMajorVersion is used to handle Python2 and Python3 differences.
_pythonMajorVersion = sys.version_info[0]
# Modes of crypting / cyphering
ECB =  0
CBC =  1
# Modes of padding
PAD_NORMAL = 1
PAD_PKCS5 = 2
# PAD_PKCS5: is a method that will unambiguously remove all padding
#      characters after decryption, when originally encrypted with
#      this padding mode.
# For a good description of the PKCS5 padding technique, see:
# http://www.faqs.org/rfcs/rfc1423.html
# The base class shared by des and triple des.
class _baseDes(object):
  def __init__(self, mode=ECB, IV=None, pad=None, padmode=PAD_NORMAL):
    if IV:
      IV = self._guardAgainstUnicode(IV)
    if pad:
      pad = self._guardAgainstUnicode(pad)
    self.block_size = 8
    # Sanity checking of arguments.
    if pad and padmode == PAD_PKCS5:
      raise ValueError("Cannot use a pad character with PAD_PKCS5")
    if IV and len(IV) != self.block_size:
      raise ValueError("Invalid Initial Value (IV), must be a multiple of " + str(self.block_size) + " bytes")
    # Set the passed in variables
    self._mode = mode
    self._iv = IV
    self._padding = pad
    self._padmode = padmode
  def getKey(self):
    """getKey() -> bytes"""
    return self.__key
  def setKey(self, key):
    """Will set the crypting key for this object."""
    key = self._guardAgainstUnicode(key)
    self.__key = key
  def getMode(self):
    """getMode() -> pyDes.ECB or pyDes.CBC"""
    return self._mode
  def setMode(self, mode):
    """Sets the type of crypting mode, pyDes.ECB or pyDes.CBC"""
    self._mode = mode
  def getPadding(self):
    """getPadding() -> bytes of length 1. Padding character."""
    return self._padding
  def setPadding(self, pad):
    """setPadding() -> bytes of length 1. Padding character."""
    if pad is not None:
      pad = self._guardAgainstUnicode(pad)
    self._padding = pad
  def getPadMode(self):
    """getPadMode() -> pyDes.PAD_NORMAL or pyDes.PAD_PKCS5"""
    return self._padmode
  def setPadMode(self, mode):
    """Sets the type of padding mode, pyDes.PAD_NORMAL or pyDes.PAD_PKCS5"""
    self._padmode = mode
  def getIV(self):
    """getIV() -> bytes"""
    return self._iv
  def setIV(self, IV):
    """Will set the Initial Value, used in conjunction with CBC mode"""
    if not IV or len(IV) != self.block_size:
      raise ValueError("Invalid Initial Value (IV), must be a multiple of " + str(self.block_size) + " bytes")
    IV = self._guardAgainstUnicode(IV)
    self._iv = IV
  def _padData(self, data, pad, padmode):
    # Pad data depending on the mode
    if padmode is None:
      # Get the default padding mode.
      padmode = self.getPadMode()
    if pad and padmode == PAD_PKCS5:
      raise ValueError("Cannot use a pad character with PAD_PKCS5")
    if padmode == PAD_NORMAL:
      if len(data) % self.block_size == 0:
        # No padding required.
        return data
      if not pad:
        # Get the default padding.
        pad = self.getPadding()
      if not pad:
        raise ValueError("Data must be a multiple of " + str(self.block_size) + " bytes in length. Use padmode=PAD_PKCS5 or set the pad character.")
      data += (self.block_size - (len(data) % self.block_size)) * pad
    elif padmode == PAD_PKCS5:
      pad_len = 8 - (len(data) % self.block_size)
      if _pythonMajorVersion < 3:
        data += pad_len * chr(pad_len)
      else:
        data += bytes([pad_len] * pad_len)
    return data
  def _unpadData(self, data, pad, padmode):
    # Unpad data depending on the mode.
    if not data:
      return data
    if pad and padmode == PAD_PKCS5:
      raise ValueError("Cannot use a pad character with PAD_PKCS5")
    if padmode is None:
      # Get the default padding mode.
      padmode = self.getPadMode()
    if padmode == PAD_NORMAL:
      if not pad:
        # Get the default padding.
        pad = self.getPadding()
      if pad:
        data = data[:-self.block_size] + \
            data[-self.block_size:].rstrip(pad)
    elif padmode == PAD_PKCS5:
      if _pythonMajorVersion < 3:
        pad_len = ord(data[-1])
      else:
        pad_len = data[-1]
      data = data[:-pad_len]
    return data
  def _guardAgainstUnicode(self, data):
    # Only accept byte strings or ascii unicode values, otherwise
    # there is no way to correctly decode the data into bytes.
    if _pythonMajorVersion < 3:
      if isinstance(data, unicode):
        raise ValueError("pyDes can only work with bytes, not Unicode strings.")
    else:
      if isinstance(data, str):
        # Only accept ascii unicode values.
        try:
          return data.encode('ascii')
        except UnicodeEncodeError:
          pass
        raise ValueError("pyDes can only work with encoded strings, not Unicode.")
    return data
#############################################################################
#           DES            #
#############################################################################
class des(_baseDes):
  """DES encryption/decrytpion class
  Supports ECB (Electronic Code Book) and CBC (Cypher Block Chaining) modes.
  pyDes.des(key,[mode], [IV])
  key -> Bytes containing the encryption key, must be exactly 8 bytes
  mode -> Optional argument for encryption type, can be either pyDes.ECB
    (Electronic Code Book), pyDes.CBC (Cypher Block Chaining)
  IV  -> Optional Initial Value bytes, must be supplied if using CBC mode.
    Must be 8 bytes in length.
  pad -> Optional argument, set the pad character (PAD_NORMAL) to use
    during all encrypt/decrpt operations done with this instance.
  padmode -> Optional argument, set the padding mode (PAD_NORMAL or
    PAD_PKCS5) to use during all encrypt/decrpt operations done
    with this instance.
  """
 
  # Permutation and translation tables for DES
  __pc1 = [56, 48, 40, 32, 24, 16, 8,
, 57, 49, 41, 33, 25, 17,
, 1, 58, 50, 42, 34, 26,
, 10, 2, 59, 51, 43, 35,
, 54, 46, 38, 30, 22, 14,
, 61, 53, 45, 37, 29, 21,
, 5, 60, 52, 44, 36, 28,
, 12, 4, 27, 19, 11, 3
  ]
  # number left rotations of pc1
  __left_rotations = [
, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
  ]
  # permuted choice key (table 2)
  __pc2 = [
, 16, 10, 23, 0, 4,
, 27, 14, 5, 20, 9,
, 18, 11, 3, 25, 7,
, 6, 26, 19, 12, 1,
, 51, 30, 36, 46, 54,
, 39, 50, 44, 32, 47,
, 48, 38, 55, 33, 52,
, 41, 49, 35, 28, 31
  ]
  # initial permutation IP
  __ip = [57, 49, 41, 33, 25, 17, 9, 1,
, 51, 43, 35, 27, 19, 11, 3,
, 53, 45, 37, 29, 21, 13, 5,
, 55, 47, 39, 31, 23, 15, 7,
, 48, 40, 32, 24, 16, 8, 0,
, 50, 42, 34, 26, 18, 10, 2,
, 52, 44, 36, 28, 20, 12, 4,
, 54, 46, 38, 30, 22, 14, 6
  ]
  # Expansion table for turning 32 bit blocks into 48 bits
  __expansion_table = [
, 0, 1, 2, 3, 4,
, 4, 5, 6, 7, 8,
, 8, 9, 10, 11, 12,
, 12, 13, 14, 15, 16,
, 16, 17, 18, 19, 20,
, 20, 21, 22, 23, 24,
, 24, 25, 26, 27, 28,
, 28, 29, 30, 31, 0
  ]
  # The (in)famous S-boxes
  __sbox = [
    # S1
    [14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13],
    # S2
    [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9],
    # S3
    [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12],
    # S4
    [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14],
    # S5
    [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3],
    # S6
    [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13],
    # S7
    [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12],
    # S8
    [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11],
  ]
 
  # 32-bit permutation function P used on the output of the S-boxes
  __p = [
, 6, 19, 20, 28, 11,
, 16, 0, 14, 22, 25,
, 17, 30, 9, 1, 7,
,13, 31, 26, 2, 8,
, 12, 29, 5, 21, 10,
, 24
  ]
  # final permutation IP^-1
  __fp = [
, 7, 47, 15, 55, 23, 63, 31,
, 6, 46, 14, 54, 22, 62, 30,
, 5, 45, 13, 53, 21, 61, 29,
, 4, 44, 12, 52, 20, 60, 28,
, 3, 43, 11, 51, 19, 59, 27,
, 2, 42, 10, 50, 18, 58, 26,
, 1, 41, 9, 49, 17, 57, 25,
, 0, 40, 8, 48, 16, 56, 24
  ]
  # Type of crypting being done
  ENCRYPT =  0x00
  DECRYPT =  0x01
  # Initialisation
  def __init__(self, key, mode=ECB, IV=None, pad=None, padmode=PAD_NORMAL):
    # Sanity checking of arguments.
    if len(key) != 8:
      raise ValueError("Invalid DES key size. Key must be exactly 8 bytes long.")
    _baseDes.__init__(self, mode, IV, pad, padmode)
    self.key_size = 8
    self.L = []
    self.R = []
    self.Kn = [ [0] * 48 ] * 16  # 16 48-bit keys (K1 - K16)
    self.final = []
    self.setKey(key)
  def setKey(self, key):
    """Will set the crypting key for this object. Must be 8 bytes."""
    _baseDes.setKey(self, key)
    self.__create_sub_keys()
  def __String_to_BitList(self, data):
    """Turn the string data, into a list of bits (1, 0)'s"""
    if _pythonMajorVersion < 3:
      # Turn the strings into integers. Python 3 uses a bytes
      # class, which already has this behaviour.
      data = [ord(c) for c in data]
    l = len(data) * 8
    result = [0] * l
    pos = 0
    for ch in data:
      i = 7
      while i >= 0:
        if ch & (1 << i) != 0:
          result[pos] = 1
        else:
          result[pos] = 0
        pos += 1
        i -= 1
    return result
  def __BitList_to_String(self, data):
    """Turn the list of bits -> data, into a string"""
    result = []
    pos = 0
    c = 0
    while pos < len(data):
      c += data[pos] << (7 - (pos % 8))
      if (pos % 8) == 7:
        result.append(c)
        c = 0
      pos += 1
    if _pythonMajorVersion < 3:
      return ''.join([ chr(c) for c in result ])
    else:
      return bytes(result)
  def __permutate(self, table, block):
    """Permutate this block with the specified table"""
    return list(map(lambda x: block[x], table))
  # Transform the secret key, so that it is ready for data processing
  # Create the 16 subkeys, K[1] - K[16]
  def __create_sub_keys(self):
    """Create the 16 subkeys K[1] to K[16] from the given key"""
    key = self.__permutate(des.__pc1, self.__String_to_BitList(self.getKey()))
    i = 0
    # Split into Left and Right sections
    self.L = key[:28]
    self.R = key[28:]
    while i < 16:
      j = 0
      # Perform circular left shifts
      while j < des.__left_rotations[i]:
        self.L.append(self.L[0])
        del self.L[0]
        self.R.append(self.R[0])
        del self.R[0]
        j += 1
      # Create one of the 16 subkeys through pc2 permutation
      self.Kn[i] = self.__permutate(des.__pc2, self.L + self.R)
      i += 1
  # Main part of the encryption algorithm, the number cruncher :)
  def __des_crypt(self, block, crypt_type):
    """Crypt the block of data through DES bit-manipulation"""
    block = self.__permutate(des.__ip, block)
    self.L = block[:32]
    self.R = block[32:]
    # Encryption starts from Kn[1] through to Kn[16]
    if crypt_type == des.ENCRYPT:
      iteration = 0
      iteration_adjustment = 1
    # Decryption starts from Kn[16] down to Kn[1]
    else:
      iteration = 15
      iteration_adjustment = -1
    i = 0
    while i < 16:
      # Make a copy of R[i-1], this will later become L[i]
      tempR = self.R[:]
      # Permutate R[i - 1] to start creating R[i]
      self.R = self.__permutate(des.__expansion_table, self.R)
      # Exclusive or R[i - 1] with K[i], create B[1] to B[8] whilst here
      self.R = list(map(lambda x, y: x ^ y, self.R, self.Kn[iteration]))
      B = [self.R[:6], self.R[6:12], self.R[12:18], self.R[18:24], self.R[24:30], self.R[30:36], self.R[36:42], self.R[42:]]
      # Optimization: Replaced below commented code with above
      #j = 0
      #B = []
      #while j < len(self.R):
      #  self.R[j] = self.R[j] ^ self.Kn[iteration][j]
      #  j += 1
      #  if j % 6 == 0:
      #    B.append(self.R[j-6:j])
      # Permutate B[1] to B[8] using the S-Boxes
      j = 0
      Bn = [0] * 32
      pos = 0
      while j < 8:
        # Work out the offsets
        m = (B[j][0] << 1) + B[j][5]
        n = (B[j][1] << 3) + (B[j][2] << 2) + (B[j][3] << 1) + B[j][4]
        # Find the permutation value
        v = des.__sbox[j][(m << 4) + n]
        # Turn value into bits, add it to result: Bn
        Bn[pos] = (v & 8) >> 3
        Bn[pos + 1] = (v & 4) >> 2
        Bn[pos + 2] = (v & 2) >> 1
        Bn[pos + 3] = v & 1
        pos += 4
        j += 1
      # Permutate the concatination of B[1] to B[8] (Bn)
      self.R = self.__permutate(des.__p, Bn)
      # Xor with L[i - 1]
      self.R = list(map(lambda x, y: x ^ y, self.R, self.L))
      # Optimization: This now replaces the below commented code
      #j = 0
      #while j < len(self.R):
      #  self.R[j] = self.R[j] ^ self.L[j]
      #  j += 1
      # L[i] becomes R[i - 1]
      self.L = tempR
      i += 1
      iteration += iteration_adjustment
    # Final permutation of R[16]L[16]
    self.final = self.__permutate(des.__fp, self.R + self.L)
    return self.final
 
  # Data to be encrypted/decrypted
  def crypt(self, data, crypt_type):
    """Crypt the data in blocks, running it through des_crypt()"""
    # Error check the data
    if not data:
      return ''
    if len(data) % self.block_size != 0:
      if crypt_type == des.DECRYPT: # Decryption must work on 8 byte blocks
        raise ValueError("Invalid data length, data must be a multiple of " + str(self.block_size) + " bytes\n.")
      if not self.getPadding():
        raise ValueError("Invalid data length, data must be a multiple of " + str(self.block_size) + " bytes\n. Try setting the optional padding character")
      else:
        data += (self.block_size - (len(data) % self.block_size)) * self.getPadding()
      # print "Len of data: %f" % (len(data) / self.block_size)
    if self.getMode() == CBC:
      if self.getIV():
        iv = self.__String_to_BitList(self.getIV())
      else:
        raise ValueError("For CBC mode, you must supply the Initial Value (IV) for ciphering")
    # Split the data into blocks, crypting each one seperately
    i = 0
    dict = {}
    result = []
    #cached = 0
    #lines = 0
    while i < len(data):
      # Test code for caching encryption results
      #lines += 1
      #if dict.has_key(data[i:i+8]):
        #print "Cached result for: %s" % data[i:i+8]
      #  cached += 1
      #  result.append(dict[data[i:i+8]])
      #  i += 8
      #  continue
      block = self.__String_to_BitList(data[i:i+8])
      # Xor with IV if using CBC mode
      if self.getMode() == CBC:
        if crypt_type == des.ENCRYPT:
          block = list(map(lambda x, y: x ^ y, block, iv))
          #j = 0
          #while j < len(block):
          #  block[j] = block[j] ^ iv[j]
          #  j += 1
        processed_block = self.__des_crypt(block, crypt_type)
        if crypt_type == des.DECRYPT:
          processed_block = list(map(lambda x, y: x ^ y, processed_block, iv))
          #j = 0
          #while j < len(processed_block):
          #  processed_block[j] = processed_block[j] ^ iv[j]
          #  j += 1
          iv = block
        else:
          iv = processed_block
      else:
        processed_block = self.__des_crypt(block, crypt_type)
 
      # Add the resulting crypted block to our list
      #d = self.__BitList_to_String(processed_block)
      #result.append(d)
      result.append(self.__BitList_to_String(processed_block))
      #dict[data[i:i+8]] = d
      i += 8
    # print "Lines: %d, cached: %d" % (lines, cached)
    # Return the full crypted string
    if _pythonMajorVersion < 3:
      return ''.join(result)
    else:
      return bytes.fromhex('').join(result)
  def encrypt(self, data, pad=None, padmode=None):
    """encrypt(data, [pad], [padmode]) -> bytes
    data : Bytes to be encrypted
    pad : Optional argument for encryption padding. Must only be one byte
    padmode : Optional argument for overriding the padding mode.
    The data must be a multiple of 8 bytes and will be encrypted
    with the already specified key. Data does not have to be a
    multiple of 8 bytes if the padding character is supplied, or
    the padmode is set to PAD_PKCS5, as bytes will then added to
    ensure the be padded data is a multiple of 8 bytes.
    """
    data = self._guardAgainstUnicode(data)
    if pad is not None:
      pad = self._guardAgainstUnicode(pad)
    data = self._padData(data, pad, padmode)
    return self.crypt(data, des.ENCRYPT)
  def decrypt(self, data, pad=None, padmode=None):
    """decrypt(data, [pad], [padmode]) -> bytes
    data : Bytes to be encrypted
    pad : Optional argument for decryption padding. Must only be one byte
    padmode : Optional argument for overriding the padding mode.
    The data must be a multiple of 8 bytes and will be decrypted
    with the already specified key. In PAD_NORMAL mode, if the
    optional padding character is supplied, then the un-encrypted
    data will have the padding characters removed from the end of
    the bytes. This pad removal only occurs on the last 8 bytes of
    the data (last data block). In PAD_PKCS5 mode, the special
    padding end markers will be removed from the data after decrypting.
    """
    data = self._guardAgainstUnicode(data)
    if pad is not None:
      pad = self._guardAgainstUnicode(pad)
    data = self.crypt(data, des.DECRYPT)
    return self._unpadData(data, pad, padmode)
 
#############################################################################
#         Triple DES          #
#############################################################################
class triple_des(_baseDes):
  """Triple DES encryption/decrytpion class
  This algorithm uses the DES-EDE3 (when a 24 byte key is supplied) or
  the DES-EDE2 (when a 16 byte key is supplied) encryption methods.
  Supports ECB (Electronic Code Book) and CBC (Cypher Block Chaining) modes.
  pyDes.des(key, [mode], [IV])
  key -> Bytes containing the encryption key, must be either 16 or
 bytes long
  mode -> Optional argument for encryption type, can be either pyDes.ECB
    (Electronic Code Book), pyDes.CBC (Cypher Block Chaining)
  IV  -> Optional Initial Value bytes, must be supplied if using CBC mode.
    Must be 8 bytes in length.
  pad -> Optional argument, set the pad character (PAD_NORMAL) to use
    during all encrypt/decrpt operations done with this instance.
  padmode -> Optional argument, set the padding mode (PAD_NORMAL or
    PAD_PKCS5) to use during all encrypt/decrpt operations done
    with this instance.
  """
  def __init__(self, key, mode=ECB, IV=None, pad=None, padmode=PAD_NORMAL):
    _baseDes.__init__(self, mode, IV, pad, padmode)
    self.setKey(key)
  def setKey(self, key):
    """Will set the crypting key for this object. Either 16 or 24 bytes long."""
    self.key_size = 24 # Use DES-EDE3 mode
    if len(key) != self.key_size:
      if len(key) == 16: # Use DES-EDE2 mode
        self.key_size = 16
      else:
        raise ValueError("Invalid triple DES key size. Key must be either 16 or 24 bytes long")
    if self.getMode() == CBC:
      if not self.getIV():
        # Use the first 8 bytes of the key
        self._iv = key[:self.block_size]
      if len(self.getIV()) != self.block_size:
        raise ValueError("Invalid IV, must be 8 bytes in length")
    self.__key1 = des(key[:8], self._mode, self._iv,
         self._padding, self._padmode)
    self.__key2 = des(key[8:16], self._mode, self._iv,
         self._padding, self._padmode)
    if self.key_size == 16:
      self.__key3 = self.__key1
    else:
      self.__key3 = des(key[16:], self._mode, self._iv,
           self._padding, self._padmode)
    _baseDes.setKey(self, key)
  # Override setter methods to work on all 3 keys.
  def setMode(self, mode):
    """Sets the type of crypting mode, pyDes.ECB or pyDes.CBC"""
    _baseDes.setMode(self, mode)
    for key in (self.__key1, self.__key2, self.__key3):
      key.setMode(mode)
  def setPadding(self, pad):
    """setPadding() -> bytes of length 1. Padding character."""
    _baseDes.setPadding(self, pad)
    for key in (self.__key1, self.__key2, self.__key3):
      key.setPadding(pad)
  def setPadMode(self, mode):
    """Sets the type of padding mode, pyDes.PAD_NORMAL or pyDes.PAD_PKCS5"""
    _baseDes.setPadMode(self, mode)
    for key in (self.__key1, self.__key2, self.__key3):
      key.setPadMode(mode)
  def setIV(self, IV):
    """Will set the Initial Value, used in conjunction with CBC mode"""
    _baseDes.setIV(self, IV)
    for key in (self.__key1, self.__key2, self.__key3):
      key.setIV(IV)
  def encrypt(self, data, pad=None, padmode=None):
    """encrypt(data, [pad], [padmode]) -> bytes
    data : bytes to be encrypted
    pad : Optional argument for encryption padding. Must only be one byte
    padmode : Optional argument for overriding the padding mode.
    The data must be a multiple of 8 bytes and will be encrypted
    with the already specified key. Data does not have to be a
    multiple of 8 bytes if the padding character is supplied, or
    the padmode is set to PAD_PKCS5, as bytes will then added to
    ensure the be padded data is a multiple of 8 bytes.
    """
    ENCRYPT = des.ENCRYPT
    DECRYPT = des.DECRYPT
    data = self._guardAgainstUnicode(data)
    if pad is not None:
      pad = self._guardAgainstUnicode(pad)
    # Pad the data accordingly.
    data = self._padData(data, pad, padmode)
    if self.getMode() == CBC:
      self.__key1.setIV(self.getIV())
      self.__key2.setIV(self.getIV())
      self.__key3.setIV(self.getIV())
      i = 0
      result = []
      while i < len(data):
        block = self.__key1.crypt(data[i:i+8], ENCRYPT)
        block = self.__key2.crypt(block, DECRYPT)
        block = self.__key3.crypt(block, ENCRYPT)
        self.__key1.setIV(block)
        self.__key2.setIV(block)
        self.__key3.setIV(block)
        result.append(block)
        i += 8
      if _pythonMajorVersion < 3:
        return ''.join(result)
      else:
        return bytes.fromhex('').join(result)
    else:
      data = self.__key1.crypt(data, ENCRYPT)
      data = self.__key2.crypt(data, DECRYPT)
      return self.__key3.crypt(data, ENCRYPT)
  def decrypt(self, data, pad=None, padmode=None):
    """decrypt(data, [pad], [padmode]) -> bytes
    data : bytes to be encrypted
    pad : Optional argument for decryption padding. Must only be one byte
    padmode : Optional argument for overriding the padding mode.
    The data must be a multiple of 8 bytes and will be decrypted
    with the already specified key. In PAD_NORMAL mode, if the
    optional padding character is supplied, then the un-encrypted
    data will have the padding characters removed from the end of
    the bytes. This pad removal only occurs on the last 8 bytes of
    the data (last data block). In PAD_PKCS5 mode, the special
    padding end markers will be removed from the data after
    decrypting, no pad character is required for PAD_PKCS5.
    """
    ENCRYPT = des.ENCRYPT
    DECRYPT = des.DECRYPT
    data = self._guardAgainstUnicode(data)
    if pad is not None:
      pad = self._guardAgainstUnicode(pad)
    if self.getMode() == CBC:
      self.__key1.setIV(self.getIV())
      self.__key2.setIV(self.getIV())
      self.__key3.setIV(self.getIV())
      i = 0
      result = []
      while i < len(data):
        iv = data[i:i+8]
        block = self.__key3.crypt(iv,  DECRYPT)
        block = self.__key2.crypt(block, ENCRYPT)
        block = self.__key1.crypt(block, DECRYPT)
        self.__key1.setIV(iv)
        self.__key2.setIV(iv)
        self.__key3.setIV(iv)
        result.append(block)
        i += 8
      if _pythonMajorVersion < 3:
        data = ''.join(result)
      else:
        data = bytes.fromhex('').join(result)
    else:
      data = self.__key3.crypt(data, DECRYPT)
      data = self.__key2.crypt(data, ENCRYPT)
      data = self.__key1.crypt(data, DECRYPT)
    return self._unpadData(data, pad, padmode)

希望本文所述对大家的Python程序设计有所帮助。

相关文章

热门资讯

2022年最旺的微信头像大全 微信头像2022年最新版图片
2022年最旺的微信头像大全 微信头像2022年最新版图片 2022-01-10
蜘蛛侠3英雄无归3正片免费播放 蜘蛛侠3在线观看免费高清完整
蜘蛛侠3英雄无归3正片免费播放 蜘蛛侠3在线观看免费高清完整 2021-08-24
背刺什么意思 网络词语背刺是什么梗
背刺什么意思 网络词语背刺是什么梗 2020-05-22
yue是什么意思 网络流行语yue了是什么梗
yue是什么意思 网络流行语yue了是什么梗 2020-10-11
暖暖日本高清免费中文 暖暖在线观看免费完整版韩国
暖暖日本高清免费中文 暖暖在线观看免费完整版韩国 2021-05-08
返回顶部