1
2 __author__="Andrew Pennebaker (andrew.pennebaker@gmail.com)"
3 __date__="21 Dec 2005 - 17 Jul 2006"
4 __copyright__="Copyright 2006 Andrew Pennebaker"
5 __license__="GPL"
6 __version__="0.3"
7 __URL__="http://snippets.dzone.com/posts/show/2889"
8
9 import HashFunction
10
11 class Adler32(HashFunction.HashFunction):
12 BLOCK_SIZE=1
13 DIGEST_SIZE=2
14
15 INIT=0x0001
16 SUM_REQ="Sum >= 0"
17
18 BASE=65521
19
20 TEST_DATA="abc"
21 TEST_HASH=0x24d0127
22
23 def __init__(self, sum=0x0001):
24 self.sum=sum
25
26 def sumValid(self, sum):
27 return sum>=0
28
29 def _update(self, b):
30 s1=self.sum&0xffff
31 s2=(self.sum>>16)&0xffff
32
33 s1=(s1+(b&0xff))%self.BASE
34 s2=(s1+s2)%self.BASE
35
36 self.sum=(s2<<16)|s1
37
38 def digest(self):
39 return self.sum
40
41 def formatDigest(self):
42 return "%02x" % (self.digest())
43
44 def unformatDigest(self, hash):
45 return int(hash, 16)
46
47 if __name__=="__main__":
48 HashFunction.main(Adler32, "Adler32.py")
