How to use

multiplyWTnaf

method

in

org.spongycastle.math.ec.WTauNafMultiplier

/**
 * Multiplies a {@link org.spongycastle.math.ec.ECPoint.F2m ECPoint.F2m}
 * by <code>k</code> using the reduced <code>&tau;</code>-adic NAF (RTNAF)
 * method.
 * @param p The ECPoint.F2m to multiply.
 * @param k The integer by which to multiply <code>k</code>.
 * @return <code>p</code> multiplied by <code>k</code>.
 */
public ECPoint multiply(ECPoint point, BigInteger k, PreCompInfo preCompInfo)
{
  if (!(point instanceof ECPoint.F2m))
  {
    throw new IllegalArgumentException("Only ECPoint.F2m can be " +
        "used in WTauNafMultiplier");
  }
  ECPoint.F2m p = (ECPoint.F2m)point;
  ECCurve.F2m curve = (ECCurve.F2m) p.getCurve();
  int m = curve.getM();
  byte a = curve.getA().toBigInteger().byteValue();
  byte mu = curve.getMu();
  BigInteger[] s = curve.getSi();
  ZTauElement rho = Tnaf.partModReduction(k, m, a, s, mu, (byte)10);
  return multiplyWTnaf(p, rho, preCompInfo, a, mu);
}

/**
 * Multiplies a {@link org.spongycastle.math.ec.ECPoint.AbstractF2m ECPoint.AbstractF2m}
 * by <code>k</code> using the reduced <code>&tau;</code>-adic NAF (RTNAF)
 * method.
 * @param point The ECPoint.AbstractF2m to multiply.
 * @param k The integer by which to multiply <code>k</code>.
 * @return <code>p</code> multiplied by <code>k</code>.
 */
protected ECPoint multiplyPositive(ECPoint point, BigInteger k)
{
  if (!(point instanceof ECPoint.AbstractF2m))
  {
    throw new IllegalArgumentException("Only ECPoint.AbstractF2m can be " +
        "used in WTauNafMultiplier");
  }
  ECPoint.AbstractF2m p = (ECPoint.AbstractF2m)point;
  ECCurve.AbstractF2m curve = (ECCurve.AbstractF2m)p.getCurve();
  int m = curve.getFieldSize();
  byte a = curve.getA().toBigInteger().byteValue();
  byte mu = Tnaf.getMu(a);
  BigInteger[] s = curve.getSi();
  ZTauElement rho = Tnaf.partModReduction(k, m, a, s, mu, (byte)10);
  return multiplyWTnaf(p, rho, curve.getPreCompInfo(p, PRECOMP_NAME), a, mu);
}