Question regarding checksuming of a file
roy at panix.com
Sun May 14 03:48:54 CEST 2006
In article <126d1u4ke4itg7f at corp.supernews.com>,
Andrew Robert <andrew.arobert at gmail.com> wrote:
> Good evening,
> I need to generate checksums of a file, store the value in a variable,
> and pass it along for later comparison.
> The MD5 module would seem to do the trick but I'm sketchy on implementation.
> The nearest I can see would be
> import md5
> contents = open(self.file_name,"rb").read()
> However this does not appear to be actually returning the checksum.
> Does anyone have insight into where I am going wrong?
After calling update(), you need to call digest(). Update() only updates
the internal state of the md5 state machine; digest() returns the hash.
Also, for the code above, it's m.update(), not md5.update(). Update() is a
method of an md5 instance object, not the md5 module itself.
Lastly, the md5 algorithm is known to be weak. If you're doing md5 to
maintain compatability with some pre-existing implementation, that's one
thing. But, if you're starting something new from scratch, I would suggest
using SHA-1 instead (see the sha module). SHA-1 is much stronger
cryptographically than md5. The Python API is virtually identical, so it's
no added work to switch to the stronger algorithm.
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