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The FIPS 140-3 Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms certified to FIPS 140-3 level 1. This jar contains JCE provider and low-level API for the BC-FJA version 2.0.0, FIPS Certificate #4743. Please see certificate for certified platform details.

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package org.bouncycastle.crypto.fips;

import java.math.BigInteger;

import org.bouncycastle.crypto.internal.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.internal.AsymmetricCipherKeyPairGenerator;
import org.bouncycastle.crypto.internal.KeyGenerationParameters;
import org.bouncycastle.crypto.internal.params.DhKeyGenerationParameters;
import org.bouncycastle.crypto.internal.params.DhParameters;
import org.bouncycastle.crypto.internal.params.DhPrivateKeyParameters;
import org.bouncycastle.crypto.internal.params.DhPublicKeyParameters;

/**
 * a Diffie-Hellman key pair generator.
 *
 * This generates keys consistent for use in the MTI/A0 key agreement protocol
 * as described in "Handbook of Applied Cryptography", Pages 516-519.
 */
class DhKeyPairGenerator
    implements AsymmetricCipherKeyPairGenerator
{
    private DhKeyGenerationParameters param;

    public void init(
        KeyGenerationParameters param)
    {
        this.param = (DhKeyGenerationParameters)param;
    }

    public AsymmetricCipherKeyPair generateKeyPair()
    {
        DhKeyGeneratorHelper helper = DhKeyGeneratorHelper.INSTANCE;
        DhParameters dhp = param.getParameters();

        BigInteger x = helper.calculatePrivate(dhp, param.getRandom()); 
        BigInteger y = helper.calculatePublic(dhp, x);

        return new AsymmetricCipherKeyPair(
            new DhPublicKeyParameters(y, dhp),
            new DhPrivateKeyParameters(x, dhp));
    }
}