org.bouncycastle.tls.TlsECDHKeyExchange 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.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Vector;

import org.bouncycastle.tls.crypto.TlsAgreement;
import org.bouncycastle.tls.crypto.TlsCertificate;
import org.bouncycastle.tls.crypto.TlsECConfig;
import org.bouncycastle.tls.crypto.TlsSecret;

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

    protected TlsECConfigVerifier ecConfigVerifier;
    protected short[] clientECPointFormats, serverECPointFormats;

    protected TlsCredentialedAgreement agreementCredentials;
    protected TlsCertificate ecdhPeerCertificate;

    protected TlsECConfig ecConfig;
    protected TlsAgreement agreement;

    public TlsECDHKeyExchange(int keyExchange, Vector supportedSignatureAlgorithms,
        TlsECConfigVerifier ecConfigVerifier, short[] clientECPointFormats, short[] serverECPointFormats)
    {
        this(keyExchange, supportedSignatureAlgorithms, ecConfigVerifier, null, clientECPointFormats,
            serverECPointFormats);
    }

    public TlsECDHKeyExchange(int keyExchange, Vector supportedSignatureAlgorithms, TlsECConfig ecConfig,
        short[] serverECPointFormats)
    {
        this(keyExchange, supportedSignatureAlgorithms, null, ecConfig, null, serverECPointFormats);
    }

    private TlsECDHKeyExchange(int keyExchange, Vector supportedSignatureAlgorithms,
        TlsECConfigVerifier ecConfigVerifier, TlsECConfig ecConfig, short[] clientECPointFormats,
        short[] serverECPointFormats)
    {
        super(checkKeyExchange(keyExchange), supportedSignatureAlgorithms);

        this.ecConfigVerifier = ecConfigVerifier;
        this.ecConfig = ecConfig;
        this.clientECPointFormats = clientECPointFormats;
        this.serverECPointFormats = serverECPointFormats;
    }

    public void skipServerCredentials() throws IOException
    {
        if (keyExchange != KeyExchangeAlgorithm.ECDH_anon)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }
    }

    public void processServerCredentials(TlsCredentials serverCredentials) throws IOException
    {
        if (keyExchange == KeyExchangeAlgorithm.ECDH_anon)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }
        if (!(serverCredentials instanceof TlsCredentialedAgreement))
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        this.agreementCredentials = (TlsCredentialedAgreement)serverCredentials;
    }

    public void processServerCertificate(Certificate serverCertificate) throws IOException
    {
        if (keyExchange == KeyExchangeAlgorithm.ECDH_anon)
        {
            throw new TlsFatalAlert(AlertDescription.unexpected_message);
        }

        checkServerCertSigAlg(serverCertificate);

        this.ecdhPeerCertificate = validatePeerCertificate(ConnectionEnd.server, serverCertificate);
    }

    public boolean requiresServerKeyExchange()
    {
        switch (keyExchange)
        {
        case KeyExchangeAlgorithm.ECDH_anon:
        case KeyExchangeAlgorithm.ECDHE_ECDSA:
        case KeyExchangeAlgorithm.ECDHE_RSA:
            return true;
        default:
            return false;
        }
    }

    public byte[] generateServerKeyExchange() throws IOException
    {
        if (!requiresServerKeyExchange())
        {
            return null;
        }

        // ECDH_anon is handled here, ECDHE_* in a subclass

        ByteArrayOutputStream buf = new ByteArrayOutputStream();

        TlsECCUtils.writeECConfig(ecConfig, buf);

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

        generateEphemeral(buf);

        return buf.toByteArray();
    }

    public void processServerKeyExchange(InputStream input) throws IOException
    {
        if (!requiresServerKeyExchange())
        {
            throw new TlsFatalAlert(AlertDescription.unexpected_message);
        }

        // ECDH_anon is handled here, ECDHE_* in a subclass

        this.ecConfig = TlsECCUtils.receiveECConfig(ecConfigVerifier, serverECPointFormats, input);

        byte[] point = TlsUtils.readOpaque8(input);

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

        processEphemeral(clientECPointFormats, point);
    }

    public short[] getClientCertificateTypes()
    {
        if (keyExchange == KeyExchangeAlgorithm.ECDH_anon)
        {
            return null;
        }

        /*
         * 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.ecdsa_fixed_ecdh, ClientCertificateType.rsa_fixed_ecdh };
    }

    public void processClientCredentials(TlsCredentials clientCredentials) throws IOException
    {
        if (keyExchange == KeyExchangeAlgorithm.ECDH_anon)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        if (clientCredentials instanceof TlsCredentialedAgreement)
        {
            this.agreementCredentials = (TlsCredentialedAgreement)clientCredentials;

            // TODO Check that the client certificate's domain parameters match the server's?
        }
        else
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }
    }

    public void generateClientKeyExchange(OutputStream output) throws IOException
    {
        if (agreementCredentials == null)
        {
            generateEphemeral(output);
        }
    }

    public void processClientCertificate(Certificate clientCertificate) throws IOException
    {
        if (keyExchange == KeyExchangeAlgorithm.ECDH_anon)
        {
            throw new TlsFatalAlert(AlertDescription.unexpected_message);
        }

        if (agreementCredentials != null)
        {
            // TODO[tls-ops] Where to check that the domain parameters match the server's?
            this.ecdhPeerCertificate = validatePeerCertificate(ConnectionEnd.client, clientCertificate);
        }
    }

    public void processClientKeyExchange(InputStream input) throws IOException
    {
        if (ecdhPeerCertificate != null)
        {
            // For ecdsa_fixed_ecdh and rsa_fixed_ecdh, the key arrived in the client certificate
            return;
        }

        byte[] point = TlsUtils.readOpaque8(input);

        processEphemeral(serverECPointFormats, point);
    }

    public TlsSecret generatePreMasterSecret() throws IOException
    {
        if (agreementCredentials != null)
        {
            return agreementCredentials.generateAgreement(ecdhPeerCertificate);
        }

        if (agreement != null)
        {
            return agreement.calculateSecret();
        }

        throw new TlsFatalAlert(AlertDescription.internal_error);
    }

    protected void generateEphemeral(OutputStream output) throws IOException
    {
        byte[] point = agreement.generateEphemeral();
        TlsUtils.writeOpaque8(point, output);
    }

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

        this.agreement.receivePeerValue(point);
    }

    protected TlsCertificate validatePeerCertificate(int connectionEnd, Certificate peerCertificate) throws IOException
    {
        if (peerCertificate.isEmpty())
        {
            throw new TlsFatalAlert(AlertDescription.bad_certificate);
        }

        return peerCertificate.getCertificateAt(0).useInRole(connectionEnd, keyExchange);
    }
}