RFR: 8294997: Improve ECC math operations

[Xue-Lei Andrew Fan]

On Fri, 7 Oct 2022 21:11:39 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> This patch rewrites some BigInteger and curve point operations used in EC calculations:
> - coefficient * 2^power is equivalent to coefficient << power
> - number mod 2^n is equivalent to number & (2^n-1)
> - pair of IntegerModuloP operations:
> t2 = t1+t1
> t1 = t1+t2
> is equivalent to t1=t1*3, which is now implemented more efficiently.
> 
> Benchmarked the code using not-yet-merged benchmark from #10544. Results on x64 before:
> 
> Benchmark        (messageLength)   Mode  Cnt     Score   Error  Units
> Signatures.sign               64  thrpt   15  1578.907 ± 1.522  ops/s
> 
> After:
> 
> Benchmark        (messageLength)   Mode  Cnt     Score   Error  Units
> Signatures.sign               64  thrpt   15  1679.495 ± 3.883  ops/s
> 
> Greatest part of the improvement is related to ECOperations changes; BigInteger modifications provide only marginal gains (1584 ops/s without ECOperations changes).
> 
> Tier1-3 tests continue to pass.

src/java.base/share/classes/sun/security/provider/DSAParameterGenerator.java line 240:

> 238:                     W = W.add(V[i].shiftLeft(i * outLen));
> 239:                 }
> 240:                 W = W.add((V[n].mod(BigInteger.TWO.pow(b)))

Did you want to update the "BigInteger.TWO.pow(b)" as well?

src/java.base/share/classes/sun/security/util/math/intpoly/IntegerPolynomial.java line 332:

> 330: 
> 331:     protected void setLimbsValuePositive(BigInteger v, long[] limbs) {
> 332:         assert bitsPerLimb < 32;

I may have this assert in the constructors as it is a final field.

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PR: https://git.openjdk.org/jdk/pull/10614