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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for Java 1.8 and later with debug enabled.

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package org.bouncycastle.crypto.generators;

import java.math.BigInteger;

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.AsymmetricCipherKeyPairGenerator;
import org.bouncycastle.crypto.CryptoServicePurpose;
import org.bouncycastle.crypto.CryptoServicesRegistrar;
import org.bouncycastle.crypto.KeyGenerationParameters;
import org.bouncycastle.crypto.constraints.ConstraintUtils;
import org.bouncycastle.crypto.constraints.DefaultServiceProperties;
import org.bouncycastle.crypto.params.DHParameters;
import org.bouncycastle.crypto.params.ElGamalKeyGenerationParameters;
import org.bouncycastle.crypto.params.ElGamalParameters;
import org.bouncycastle.crypto.params.ElGamalPrivateKeyParameters;
import org.bouncycastle.crypto.params.ElGamalPublicKeyParameters;

/**
 * a ElGamal key pair generator.
 * 

* This generates keys consistent for use with ElGamal as described in * page 164 of "Handbook of Applied Cryptography". */ public class ElGamalKeyPairGenerator implements AsymmetricCipherKeyPairGenerator { private ElGamalKeyGenerationParameters param; public void init( KeyGenerationParameters param) { this.param = (ElGamalKeyGenerationParameters)param; CryptoServicesRegistrar.checkConstraints(new DefaultServiceProperties("ElGamalKeyGen", ConstraintUtils.bitsOfSecurityFor(this.param.getParameters().getP()), this.param.getParameters(), CryptoServicePurpose.KEYGEN)); } public AsymmetricCipherKeyPair generateKeyPair() { DHKeyGeneratorHelper helper = DHKeyGeneratorHelper.INSTANCE; ElGamalParameters egp = param.getParameters(); DHParameters dhp = new DHParameters(egp.getP(), egp.getG(), null, egp.getL()); BigInteger x = helper.calculatePrivate(dhp, param.getRandom()); BigInteger y = helper.calculatePublic(dhp, x); return new AsymmetricCipherKeyPair( new ElGamalPublicKeyParameters(y, egp), new ElGamalPrivateKeyParameters(x, egp)); } }





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