3 ### Cryptographic primitives
5 ### (c) 2013 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
10 ### This file is part of Chopwood: a password-changing service.
12 ### Chopwood is free software; you can redistribute it and/or modify
13 ### it under the terms of the GNU Affero General Public License as
14 ### published by the Free Software Foundation; either version 3 of the
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20 ### GNU Affero General Public License for more details.
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23 ### License along with Chopwood; if not, see
24 ### <http://www.gnu.org/licenses/>.
26 from struct
import pack
, unpack
28 ###--------------------------------------------------------------------------
31 def U32(x
): return x
&0xffffffff
32 def FF(x
, y
, z
): return (x
&y
) |
(~x
&z
)
33 def GG(x
, y
, z
): return (z
&x
) |
(~z
&y
)
34 def HH(x
, y
, z
): return x^y^z
35 def II(x
, y
, z
): return y^
(x|~z
)
36 def rot(x
, n
): return U32((x
<< n
) |
(x
>> 32 - n
))
37 MD5_INIT
= '0123456789abcdeffedcba9876543210'.decode('hex')
38 def compress_md5(buf
, st
= MD5_INIT
):
40 The MD5 compression function, in pure Python.
42 This is about as small as I could make it. Apply the MD5 compression
43 function to BUF, using the initial state ST (defaults to the standard
44 initialization vector); return the new state as the function value.
46 a
, b
, c
, d
= unpack('<4L', st
)
47 aa
, bb
, cc
, dd
= a
, b
, c
, d
48 x
= xx
= unpack('<16L', buf
)
49 for f
, i
, r
, k
in [(FF
, 0, 7, 0xd76aa478), (FF
, 1, 12, 0xe8c7b756),
50 (FF
, 2, 17, 0x242070db), (FF
, 3, 22, 0xc1bdceee),
51 (FF
, 4, 7, 0xf57c0faf), (FF
, 5, 12, 0x4787c62a),
52 (FF
, 6, 17, 0xa8304613), (FF
, 7, 22, 0xfd469501),
53 (FF
, 8, 7, 0x698098d8), (FF
, 9, 12, 0x8b44f7af),
54 (FF
, 10, 17, 0xffff5bb1), (FF
, 11, 22, 0x895cd7be),
55 (FF
, 12, 7, 0x6b901122), (FF
, 13, 12, 0xfd987193),
56 (FF
, 14, 17, 0xa679438e), (FF
, 15, 22, 0x49b40821),
57 (GG
, 1, 5, 0xf61e2562), (GG
, 6, 9, 0xc040b340),
58 (GG
, 11, 14, 0x265e5a51), (GG
, 0, 20, 0xe9b6c7aa),
59 (GG
, 5, 5, 0xd62f105d), (GG
, 10, 9, 0x02441453),
60 (GG
, 15, 14, 0xd8a1e681), (GG
, 4, 20, 0xe7d3fbc8),
61 (GG
, 9, 5, 0x21e1cde6), (GG
, 14, 9, 0xc33707d6),
62 (GG
, 3, 14, 0xf4d50d87), (GG
, 8, 20, 0x455a14ed),
63 (GG
, 13, 5, 0xa9e3e905), (GG
, 2, 9, 0xfcefa3f8),
64 (GG
, 7, 14, 0x676f02d9), (GG
, 12, 20, 0x8d2a4c8a),
65 (HH
, 5, 4, 0xfffa3942), (HH
, 8, 11, 0x8771f681),
66 (HH
, 11, 16, 0x6d9d6122), (HH
, 14, 23, 0xfde5380c),
67 (HH
, 1, 4, 0xa4beea44), (HH
, 4, 11, 0x4bdecfa9),
68 (HH
, 7, 16, 0xf6bb4b60), (HH
, 10, 23, 0xbebfbc70),
69 (HH
, 13, 4, 0x289b7ec6), (HH
, 0, 11, 0xeaa127fa),
70 (HH
, 3, 16, 0xd4ef3085), (HH
, 6, 23, 0x04881d05),
71 (HH
, 9, 4, 0xd9d4d039), (HH
, 12, 11, 0xe6db99e5),
72 (HH
, 15, 16, 0x1fa27cf8), (HH
, 2, 23, 0xc4ac5665),
73 (II
, 0, 6, 0xf4292244), (II
, 7, 10, 0x432aff97),
74 (II
, 14, 15, 0xab9423a7), (II
, 5, 21, 0xfc93a039),
75 (II
, 12, 6, 0x655b59c3), (II
, 3, 10, 0x8f0ccc92),
76 (II
, 10, 15, 0xffeff47d), (II
, 1, 21, 0x85845dd1),
77 (II
, 8, 6, 0x6fa87e4f), (II
, 15, 10, 0xfe2ce6e0),
78 (II
, 6, 15, 0xa3014314), (II
, 13, 21, 0x4e0811a1),
79 (II
, 4, 6, 0xf7537e82), (II
, 11, 10, 0xbd3af235),
80 (II
, 2, 15, 0x2ad7d2bb), (II
, 9, 21, 0xeb86d391)]:
81 b
, c
, d
, a
= U32(rot(U32(a
+ f(b
, c
, d
) + x
[i
] + k
), r
) + b
), b
, c
, d
82 return pack('<4L', U32(a
+ aa
), U32(b
+ bb
), U32(c
+ cc
), U32(d
+ dd
))
84 ###----- That's all, folks --------------------------------------------------