org.bouncycastle.jce.ECPointUtil.java Source code

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Here is the source code for org.bouncycastle.jce.ECPointUtil.java

Source

package org.bouncycastle.jce;

import java.security.spec.ECFieldF2m;
import java.security.spec.ECFieldFp;
import java.security.spec.ECPoint;
import java.security.spec.EllipticCurve;

import org.bouncycastle.jcajce.provider.asymmetric.util.EC5Util;
import org.bouncycastle.math.ec.ECCurve;

/**
 * Utility class for handling EC point decoding.
 */
public class ECPointUtil {
    /**
     * Decode a point on this curve which has been encoded using point
     * compression (X9.62 s 4.2.1 and 4.2.2) or regular encoding.
     * 
     * @param curve
     *            The elliptic curve.
     * @param encoded
     *            The encoded point.
     * @return the decoded point.
     */
    public static ECPoint decodePoint(EllipticCurve curve, byte[] encoded) {
        ECCurve c = null;

        if (curve.getField() instanceof ECFieldFp) {
            c = new ECCurve.Fp(((ECFieldFp) curve.getField()).getP(), curve.getA(), curve.getB());
        } else {
            int k[] = ((ECFieldF2m) curve.getField()).getMidTermsOfReductionPolynomial();

            if (k.length == 3) {
                c = new ECCurve.F2m(((ECFieldF2m) curve.getField()).getM(), k[2], k[1], k[0], curve.getA(),
                        curve.getB());
            } else {
                c = new ECCurve.F2m(((ECFieldF2m) curve.getField()).getM(), k[0], curve.getA(), curve.getB());
            }
        }

        return EC5Util.convertPoint(c.decodePoint(encoded));
    }
}