binascii.crc32 results not matching

Peter Hansen peter at engcorp.com
Sat Dec 10 06:59:58 CET 2005


Larry Bates wrote:
> I'm trying to get the results of binascii.crc32
> to match the results of another utility that produces
> 32 bit unsigned CRCs.  

What other utility?  As Tim says, there are many CRC32s... the 
background notes on this one happen to stumble out at the top of the 
list in response to googling for "zip file crc32 checksum polynomial", 
though I'm sure there are easier ways.  The binascii docs say its CRC32 
is compatible with the Zip file checksum, but they don't describe it 
further.

Generally CRCs are described in terms of their "polynomial", though just 
quoting that isn't sufficient to describe their behaviour, but if you 
happen to know the polynomial for your utility, someone else can 
probably point you to a more appropriate routine, or perhaps explain 
what you were doing wrong if the binascii one is actually the right one..

-Peter




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