fpnafmultiplier.java

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// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   FpNafMultiplier.java

package org.bouncycastle.math.ec;

import java.math.BigInteger;

// Referenced classes of package org.bouncycastle.math.ec:
//			ECMultiplier, ECPoint, PreCompInfo

class FpNafMultiplier
	implements ECMultiplier
{

	FpNafMultiplier()
	{
	}

	public ECPoint multiply(ECPoint p, BigInteger k, PreCompInfo preCompInfo)
	{
		BigInteger e = k;
		BigInteger h = e.multiply(BigInteger.valueOf(3L));
		ECPoint neg = p.negate();
		ECPoint R = p;
		for (int i = h.bitLength() - 2; i > 0; i--)
		{
			R = R.twice();
			boolean hBit = h.testBit(i);
			boolean eBit = e.testBit(i);
			if (hBit != eBit)
				R = R.add(hBit ? p : neg);
		}

		return R;
	}
}