AES GCM slow

[Mark Christiaens]

I wrote  a little test client/server setup that transfers 100 MB of data
over an SSL socket configured to use TLS 1.2 AES GCM
(TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256).  On my i7-4770 CPU @ 3.40GHz with
OpenJDK 1.8.0-ea-b124 I get a transfer rate of around 5.2 MiB/second.  I
expected a higher speed.  Using TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 I
reach 100 MiB/s.  Is this to be expected?

For reference, here is my code:

///// Client.java

package ssl;

import javax.net.ssl.*;
import java.io.*;
import java.util.Arrays;

public class Client {

    public static void main(String[] arstring) {
        try {
            SSLSocketFactory sslsocketfactory = (SSLSocketFactory)
SSLSocketFactory.getDefault();
            SSLSocket sslsocket = (SSLSocket)
sslsocketfactory.createSocket("localhost", 9999);
            Helper.requireAESCipherSuites(sslsocket);
            sslsocket.setEnabledProtocols(new String[]{"TLSv1.2"});

            try (OutputStream outputstream = sslsocket.getOutputStream()) {
                byte[] buf = new byte[Helper.BUF_SIZE];
                Arrays.fill(buf, (byte) 1);

                for (int i = 0; i < Helper.BUF_COUNT; ++i) {
                    outputstream.write(buf);
                }

                System.out.println("Using cipher suite: " +
(sslsocket.getSession()).getCipherSuite());

                outputstream.flush();
            }

        } catch (IOException exception) {
            exception.printStackTrace();
        }
    }
}

///// Server.java

package ssl;

import javax.net.ssl.*;
import java.io.*;

public class Server {

    public static void main(String[] arstring) {
        try {
            SSLServerSocketFactory sslserversocketfactory =
(SSLServerSocketFactory) SSLServerSocketFactory.getDefault();
            SSLServerSocket sslserversocket = (SSLServerSocket)
sslserversocketfactory.createServerSocket(9999);
            SSLSocket sslsocket = (SSLSocket) sslserversocket.accept();

            InputStream inputstream = sslsocket.getInputStream();

            byte[] buf = new byte[Helper.BUF_SIZE];
            long bytesToRead = BYTES_TO_READ;

            long startTime = System.currentTimeMillis();

            while (bytesToRead > 0) {
                bytesToRead -= inputstream.read(buf);
            }

            long stopTime = System.currentTimeMillis();
            long totalTimeMs = stopTime - startTime;
            double mbRead = BYTES_TO_READ / (1024.0 * 1024);
            double totalTimeSeconds = totalTimeMs / 1000.0;
            double mibPerSecond = mbRead / totalTimeSeconds;

            System.out.println("Using cipher suite: " +
(sslsocket.getSession()).getCipherSuite());
            System.out.println("Read " + mbRead + "MiB in " +
totalTimeSeconds + "s");
            System.out.println("Bandwidth: " + mibPerSecond + "MiB/s");

        } catch (IOException exception) {
            exception.printStackTrace();
        }
    }

    private static final int BYTES_TO_READ = Helper.BUF_COUNT *
Helper.BUF_SIZE;
}

///// Helper.java

package ssl;

import java.util.*;
import java.util.regex.*;
import javax.net.ssl.*;

public class Helper {

    static int BUF_SIZE = 1024 * 1024;
    static int BUF_COUNT = 100;

    static SSLSocket requireAESCipherSuites(SSLSocket socket) {
        String supportedCipherSuites[] = socket.getSupportedCipherSuites();

        System.out.println("Supported cipher suite: " +
Arrays.toString(supportedCipherSuites));

        List<String> selectedCipherSuites = new ArrayList<>();

//        String patternString = ".*";
        String patternString = "TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256";
//        String patternString = "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256";

        Pattern pattern = Pattern.compile(patternString);

        for (String cipherSuite : supportedCipherSuites) {
            Matcher matcher = pattern.matcher(cipherSuite);
            if (matcher.find()) {
                selectedCipherSuites.add(cipherSuite);
            }
        }

        System.out.println("Selected cipher suites: " +
selectedCipherSuites);

        socket.setEnabledCipherSuites(selectedCipherSuites.toArray(new
String[0]));

        return socket;
    }
}