SSL Certificate

In this tutorial, I will guide you on How to integrate SSL Certificate in your Android Application and Fixing SSL Handshake Exception on Android Devices below API level 20.

We will use below TLS SOCKET FACTORY class.

import android.content.Context;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManagerFactory;

public class TLSSocketFactory extends SSLSocketFactory {

    private SSLSocketFactory delegate;

    public TLSSocketFactory(Context context) throws KeyManagementException, NoSuchAlgorithmException, CertificateException, KeyStoreException, IOException {

        // Loading CAs from an InputStream
        CertificateFactory cf = null;
        cf = CertificateFactory.getInstance("X.509");
        Certificate ca = null;

        // I'm using Java7. If you used Java6 close it manually with finally.
        try (InputStream cert = context.getResources().openRawResource(R.raw.ssl_cert)) {
            ca = cf.generateCertificate(cert);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (CertificateException e) {
            e.printStackTrace();
        }

        // Creating a KeyStore containing our trusted CAs
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);

        // Creating a TrustManager that trusts the CAs in our KeyStore.
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);
/*
        // Creating an SSLSocketFactory that uses our TrustManager
        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, tmf.getTrustManagers(), null);
        */
        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, tmf.getTrustManagers(), null);
        delegate = sslContext.getSocketFactory();
    }

    @Override
    public String[] getDefaultCipherSuites() {
        return delegate.getDefaultCipherSuites();
    }

    @Override
    public String[] getSupportedCipherSuites() {
        return delegate.getSupportedCipherSuites();
    }

    @Override
    public Socket createSocket() throws IOException {
        return enableTLSOnSocket(delegate.createSocket());
    }

    @Override
    public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException {
        return enableTLSOnSocket(delegate.createSocket(s, host, port, autoClose));
    }

    @Override
    public Socket createSocket(String host, int port) throws IOException, UnknownHostException {
        return enableTLSOnSocket(delegate.createSocket(host, port));
    }

    @Override
    public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException, UnknownHostException {
        return enableTLSOnSocket(delegate.createSocket(host, port, localHost, localPort));
    }

    @Override
    public Socket createSocket(InetAddress host, int port) throws IOException {
        return enableTLSOnSocket(delegate.createSocket(host, port));
    }

    @Override
    public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException {
        return enableTLSOnSocket(delegate.createSocket(address, port, localAddress, localPort));
    }

    private Socket enableTLSOnSocket(Socket socket) {
        if (socket != null && (socket instanceof SSLSocket)) {
            ((SSLSocket) socket).setEnabledProtocols(new String[]{"TLSv1.2"});
        }
        return socket;
    }
}

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