com.sun.crypto.provider.GHASH performance fix

Anthony Scarpino anthony.scarpino at
Thu Jan 15 16:24:58 UTC 2015

On 01/15/2015 03:10 AM, Florian Weimer wrote:
> On 08/18/2014 02:32 PM, Florian Weimer wrote:
>> This change addresses a severe performance regression, first introduced
>> in JDK 8, triggered by the negotiation of a GCM cipher suite in the TLS
>> implementation.  This regression is a result of the poor performance of
>> the implementation of the GHASH function.
>> I first tried to eliminate just the allocations in blockMult while still
>> retaining the byte arrays.  This did not substantially increase
>> performance in my micro-benchmark.  I then replaced the 16-byte arrays
>> with longs, replaced the inner loops with direct bit fiddling on the
>> longs, eliminated data-dependent conditionals (which are generally
>> frowned upon in cryptographic algorithms due to the risk of timing
>> attacks), and split the main loop in two, one for each half of the hash
>> state.  This is the result:
>>    <>
> Updated webrev: <>
> Anthony, could you file a bug so that I can include its number?  Thanks.

Here it is:


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