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package java.security.spec;

import java.math.BigInteger;

This immutable class specifies the set of domain parameters
used with elliptic curve cryptography (ECC).
Author:
Valerie Peng
See Also:
AlgorithmParameterSpec
Since:
1.5/**
 * This immutable class specifies the set of domain parameters
 * used with elliptic curve cryptography (ECC).
 *
 * @see AlgorithmParameterSpec
 *
 * @author Valerie Peng
 *
 * @since 1.5
 */
public class ECParameterSpec implements AlgorithmParameterSpec {

    private final EllipticCurve curve;
    private final ECPoint g;
    private final BigInteger n;
    private final int h;

    
Creates elliptic curve domain parameters based on the
specified values.
Params:
curve – the elliptic curve which this parameter
defines.
g – the generator which is also known as the base point.
n – the order of the generator g.
h – the cofactor.
Throws:
NullPointerException – if curve, g, or n is null.
IllegalArgumentException – if n or h is not positive./**
     * Creates elliptic curve domain parameters based on the
     * specified values.
     * @param curve the elliptic curve which this parameter
     * defines.
     * @param g the generator which is also known as the base point.
     * @param n the order of the generator {@code g}.
     * @param h the cofactor.
     * @exception NullPointerException if {@code curve},
     * {@code g}, or {@code n} is null.
     * @exception IllegalArgumentException if {@code n}
     * or {@code h} is not positive.
     */
    public ECParameterSpec(EllipticCurve curve, ECPoint g,
                           BigInteger n, int h) {
        if (curve == null) {
            throw new NullPointerException("curve is null");
        }
        if (g == null) {
            throw new NullPointerException("g is null");
        }
        if (n == null) {
            throw new NullPointerException("n is null");
        }
        if (n.signum() != 1) {
            throw new IllegalArgumentException("n is not positive");
        }
        if (h <= 0) {
            throw new IllegalArgumentException("h is not positive");
        }
        this.curve = curve;
        this.g = g;
        this.n = n;
        this.h = h;
    }

    
Returns the elliptic curve that this parameter defines.
Returns:
the elliptic curve that this parameter defines./**
     * Returns the elliptic curve that this parameter defines.
     * @return the elliptic curve that this parameter defines.
     */
    public EllipticCurve getCurve() {
        return curve;
    }

    
Returns the generator which is also known as the base point.
Returns:
the generator which is also known as the base point./**
     * Returns the generator which is also known as the base point.
     * @return the generator which is also known as the base point.
     */
    public ECPoint getGenerator() {
        return g;
    }

    
Returns the order of the generator.
Returns:
the order of the generator./**
     * Returns the order of the generator.
     * @return the order of the generator.
     */
    public BigInteger getOrder() {
        return n;
    }

    
Returns the cofactor.
Returns:
the cofactor./**
     * Returns the cofactor.
     * @return the cofactor.
     */
    public int getCofactor() {
        return h;
    }
}