org.bouncycastle.tls.TlsECDHEKeyExchange Maven / Gradle / Ivy

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The Bouncy Castle Java APIs for the TLS, including a JSSE provider. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.tls;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.bouncycastle.tls.crypto.TlsAgreement;
import org.bouncycastle.tls.crypto.TlsCertificate;
import org.bouncycastle.tls.crypto.TlsECConfig;
import org.bouncycastle.tls.crypto.TlsSecret;
import org.bouncycastle.util.io.TeeInputStream;

/**
 * (D)TLS ECDHE key exchange (see RFC 4492).
 */
public class TlsECDHEKeyExchange
    extends AbstractTlsKeyExchange
{
    private static int checkKeyExchange(int keyExchange)
    {
        switch (keyExchange)
        {
        case KeyExchangeAlgorithm.ECDHE_ECDSA:
        case KeyExchangeAlgorithm.ECDHE_RSA:
            return keyExchange;
        default:
            throw new IllegalArgumentException("unsupported key exchange algorithm");
        }
    }

    protected TlsECConfig ecConfig;

    protected TlsCredentialedSigner serverCredentials = null;
    protected TlsCertificate serverCertificate = null;
    protected TlsAgreement agreement;

    public TlsECDHEKeyExchange(int keyExchange)
    {
        this(keyExchange, null);
    }

    public TlsECDHEKeyExchange(int keyExchange, TlsECConfig ecConfig)
    {
        super(checkKeyExchange(keyExchange));

        this.ecConfig = ecConfig;
    }

    public void skipServerCredentials() throws IOException
    {
        throw new TlsFatalAlert(AlertDescription.internal_error);
    }

    public void processServerCredentials(TlsCredentials serverCredentials) throws IOException
    {
        this.serverCredentials = TlsUtils.requireSignerCredentials(serverCredentials);
    }

    public void processServerCertificate(Certificate serverCertificate) throws IOException
    {
        this.serverCertificate = serverCertificate.getCertificateAt(0);
    }

    public boolean requiresServerKeyExchange()
    {
        return true;
    }

    public byte[] generateServerKeyExchange() throws IOException
    {
        DigestInputBuffer digestBuffer = new DigestInputBuffer();

        TlsECCUtils.writeECConfig(ecConfig, digestBuffer);

        this.agreement = context.getCrypto().createECDomain(ecConfig).createECDH();

        generateEphemeral(digestBuffer);

        TlsUtils.generateServerKeyExchangeSignature(context, serverCredentials, null, digestBuffer);

        return digestBuffer.toByteArray();
    }

    public void processServerKeyExchange(InputStream input) throws IOException
    {
        DigestInputBuffer digestBuffer = new DigestInputBuffer();
        InputStream teeIn = new TeeInputStream(input, digestBuffer);

        this.ecConfig = TlsECCUtils.receiveECDHConfig(context, teeIn);

        byte[] point = TlsUtils.readOpaque8(teeIn, 1);

        TlsUtils.verifyServerKeyExchangeSignature(context, input, serverCertificate, null, digestBuffer);

        this.agreement = context.getCrypto().createECDomain(ecConfig).createECDH();

        processEphemeral(point);
    }

    public short[] getClientCertificateTypes()
    {
        /*
         * RFC 4492 3. [...] The ECDSA_fixed_ECDH and RSA_fixed_ECDH mechanisms are usable with
         * ECDH_ECDSA and ECDH_RSA. Their use with ECDHE_ECDSA and ECDHE_RSA is prohibited because
         * the use of a long-term ECDH client key would jeopardize the forward secrecy property of
         * these algorithms.
         */
        return new short[]{ ClientCertificateType.dss_sign, ClientCertificateType.ecdsa_sign,
            ClientCertificateType.rsa_sign };
    }

    public void processClientCredentials(TlsCredentials clientCredentials) throws IOException
    {
        TlsUtils.requireSignerCredentials(clientCredentials);
    }

    public void generateClientKeyExchange(OutputStream output) throws IOException
    {
        generateEphemeral(output);
    }

    public void processClientKeyExchange(InputStream input) throws IOException
    {
        byte[] point = TlsUtils.readOpaque8(input, 1);

        processEphemeral(point);
    }

    public TlsSecret generatePreMasterSecret() throws IOException
    {
        return agreement.calculateSecret();
    }

    protected void generateEphemeral(OutputStream output) throws IOException
    {
        byte[] point = agreement.generateEphemeral();

        TlsUtils.writeOpaque8(point, output);
    }

    protected void processEphemeral(byte[] point) throws IOException
    {
        TlsECCUtils.checkPointEncoding(ecConfig.getNamedGroup(), point);

        this.agreement.receivePeerValue(point);
    }
}