Very slow performance of AES/GCM in JDK 8 SunJCE provider

[Tim Whittington]

Hi all

I’ve noticed that the performance of the AES/GCM implementation in the JDK 8 SunJCE provider is very slow.

On a simple micro-benchmark (standard caveats etc. etc.) encrypting 10 MB blocks of random data (not decrypt) I get the following rough throughputs:

AES/ECB +UseAESIntrinsics - 600 MB/s (btw this is awesome fast for Java, up from about 300 MB/s in Java 7)
AES/ECB -UseAESIntrinsics - 120 MB/s (again a good bump from about 90 MB/s in Java 7)
AES/GCM - 4 MB/s

4 MB/s is pretty catastrophic (especially compared to the stellar baseline AES performance).

A quick peek in a profiler reveals pretty much all the time is in GHash.blockMult()/getBit()/shift().
The performance of the AES/GCM mode is comparable to other pure Java implementations without table based multiplier optimisations (which typically provide speeds in the 40-60 MB/s on the same micro-benchmark).

I wonder if the JDK implementation could adopt one of those approaches or (better) implement an intrinsic to speed this up (perhaps using the CLMUL interaction set when available).

cheers
tim

—

java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)

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