org.bouncycastle.crypto.params.DHPublicKeyParameters.java Source code

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Here is the source code for org.bouncycastle.crypto.params.DHPublicKeyParameters.java

Source

package org.bouncycastle.crypto.params;

import java.math.BigInteger;

public class DHPublicKeyParameters extends DHKeyParameters {
    private static final BigInteger ONE = BigInteger.valueOf(1);
    private static final BigInteger TWO = BigInteger.valueOf(2);

    private BigInteger y;

    public DHPublicKeyParameters(BigInteger y, DHParameters params) {
        super(false, params);

        this.y = validate(y, params);
    }

    private BigInteger validate(BigInteger y, DHParameters dhParams) {
        if (y == null) {
            throw new NullPointerException("y value cannot be null");
        }

        // TLS check
        if (y.compareTo(TWO) < 0 || y.compareTo(dhParams.getP().subtract(TWO)) > 0) {
            throw new IllegalArgumentException("invalid DH public key");
        }

        if (dhParams.getQ() != null) {
            if (ONE.equals(y.modPow(dhParams.getQ(), dhParams.getP()))) {
                return y;
            }

            throw new IllegalArgumentException("Y value does not appear to be in correct group");
        } else {
            return y; // we can't validate without Q.
        }
    }

    public BigInteger getY() {
        return y;
    }

    public int hashCode() {
        return y.hashCode() ^ super.hashCode();
    }

    public boolean equals(Object obj) {
        if (!(obj instanceof DHPublicKeyParameters)) {
            return false;
        }

        DHPublicKeyParameters other = (DHPublicKeyParameters) obj;

        return other.getY().equals(y) && super.equals(obj);
    }
}