package org.bouncycastle.tls.crypto.impl.bc;
import java.io.IOException;
import java.math.BigInteger;
import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.agreement.DHBasicAgreement;
import org.bouncycastle.crypto.generators.DHBasicKeyPairGenerator;
import org.bouncycastle.crypto.params.DHKeyGenerationParameters;
import org.bouncycastle.crypto.params.DHParameters;
import org.bouncycastle.crypto.params.DHPrivateKeyParameters;
import org.bouncycastle.crypto.params.DHPublicKeyParameters;
import org.bouncycastle.tls.AlertDescription;
import org.bouncycastle.tls.TlsFatalAlert;
import org.bouncycastle.tls.crypto.TlsAgreement;
import org.bouncycastle.tls.crypto.TlsDHConfig;
import org.bouncycastle.tls.crypto.TlsDHDomain;
import org.bouncycastle.util.BigIntegers;
/**
* BC light-weight support class for Diffie-Hellman key pair generation and key agreement over a specified Diffie-Hellman configuration.
*/
public class BcTlsDHDomain implements TlsDHDomain
{
protected BcTlsCrypto crypto;
protected TlsDHConfig dhConfig;
protected DHParameters dhDomain;
public BcTlsDHDomain(BcTlsCrypto crypto, TlsDHConfig dhConfig)
{
this.crypto = crypto;
this.dhConfig = dhConfig;
this.dhDomain = getParameters(dhConfig);
}
public byte[] calculateDHAgreement(DHPublicKeyParameters publicKey, DHPrivateKeyParameters privateKey)
{
DHBasicAgreement basicAgreement = new DHBasicAgreement();
basicAgreement.init(privateKey);
BigInteger agreementValue = basicAgreement.calculateAgreement(publicKey);
/*
* RFC 5246 8.1.2. Leading bytes of Z that contain all zero bits are stripped before it is
* used as the pre_master_secret.
*/
return BigIntegers.asUnsignedByteArray(agreementValue);
}
public TlsAgreement createDH()
{
return new BcTlsDH(this);
}
public static BigInteger decodeParameter(byte[] encoding) throws IOException
{
return new BigInteger(1, encoding);
}
public DHPublicKeyParameters decodePublicKey(byte[] encoding) throws IOException
{
try
{
BigInteger y = decodeParameter(encoding);
// TODO Check RFCs for any validation that could/should be done here
return new DHPublicKeyParameters(y, dhDomain);
}
catch (RuntimeException e)
{
throw new TlsFatalAlert(AlertDescription.illegal_parameter, e);
}
}
public byte[] encodeParameter(BigInteger x) throws IOException
{
return BigIntegers.asUnsignedByteArray(x);
}
public byte[] encodePublicKey(DHPublicKeyParameters publicKey) throws IOException
{
return encodeParameter(publicKey.getY());
}
public AsymmetricCipherKeyPair generateKeyPair()
{
DHBasicKeyPairGenerator keyPairGenerator = new DHBasicKeyPairGenerator();
keyPairGenerator.init(new DHKeyGenerationParameters(crypto.getSecureRandom(), dhDomain));
return keyPairGenerator.generateKeyPair();
}
public BcTlsCrypto getCrypto()
{
return crypto;
}
public DHParameters getParameters(TlsDHConfig dhConfig)
{
// TODO There's a draft RFC for negotiated (named) groups
BigInteger[] pg = dhConfig.getExplicitPG();
if (pg != null)
{
return new DHParameters(pg[0], pg[1]);
}
throw new IllegalStateException("No DH configuration provided");
}
}