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Posted to commits@harmony.apache.org by "Daniel Fridlender (JIRA)" <ji...@apache.org> on 2006/11/07 22:40:52 UTC
[jira] Commented: (HARMONY-1981) [classlib][java.math] optimization
of BigInteger.modPow and BigInteger.pow
[ http://issues.apache.org/jira/browse/HARMONY-1981?page=comments#action_12447930 ]
Daniel Fridlender commented on HARMONY-1981:
--------------------------------------------
Thanks, Alexey, the patch was applied as expected.
This patch improved the performance of modPow and its cryptographic applications.
Comparing modPow before and after the patch gave us the following figures:
size before after
16 5.636e+05 6.351e+05
32 9.727e+04 1.293e+05
48 3.225e+04 4.623e+04
64 1.436e+04 2.148e+04
128 1941 3114
192 590 970
256 252 420
384 75 127
512 32 55
where the first column shows the size of the arguments in bytes and
the other two the number of modPow operations per 100 seconds before
and after the patch.
As for cryptographic applications, for instance, for RSA key generation we obtained:
size before after
512 3,00 2,06
1024 20,17 13,58
2048 280,38 149,48
where the first column shows the length of the key in bits and the
other two the time in seconds taken to perform 30 iterations of the
key generation algorithm before and after the patch.
Thanks again!
> [classlib][java.math] optimization of BigInteger.modPow and BigInteger.pow
> --------------------------------------------------------------------------
>
> Key: HARMONY-1981
> URL: http://issues.apache.org/jira/browse/HARMONY-1981
> Project: Harmony
> Issue Type: Improvement
> Reporter: Daniel Fridlender
> Assigned To: Alexey Petrenko
> Priority: Minor
> Attachments: pow_modPow.diff
>
>
> The method modPow is important for cryptographic applications. We optimized it by
> + using sliding windows instead of the simpleminded square-and-multiply technique
> + optimizing Montogomery multiplication when computing squares
> We also optimized pow with a more efficient computation of squares.
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