[ python-Bugs-1618455 ] HMAC can get a 6x performance increase easily

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Bugs item #1618455, was opened at 2006-12-18 18:12
Message generated for change (Comment added) made by bmaurer
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Category: Python Library
Group: None
Status: Closed
Resolution: Accepted
Priority: 5
Private: No
Submitted By: Ben Maurer (bmaurer)
Assigned to: A.M. Kuchling (akuchling)
Summary: HMAC can get a 6x performance increase easily

Initial Comment:
The attached patch increases the performance of HMAC by a factor of 6. It does so by avoiding useing join/map in the strxor and using a lookup table. It would be faster just to do xor at the string level, but it's not clear that can be done without help from C.

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>Comment By: Ben Maurer (bmaurer)
Date: 2006-12-19 09:58

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The performance increase is if you call hmac.new a lot. I did a benchmark
on a relatively small amount of cleartext (50 bytes). This was actually
something I needed to use.

One thing I found -- reusing teh same hmac option helps *ALOT* the hmac
docs don't make it clear how much this will help.

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Comment By: A.M. Kuchling (akuchling)
Date: 2006-12-19 09:16

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Thanks for your patch; I've modified it to remove _strxor() completely and
applied the change as rev. 53065.  

When I tried a trivial benchmark, the speed improvement wasn't anywhere
near 6X, and was more like 7%.  The patch is still worth applying because
it also simplifies the code.


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