SSLSocketFactory in Android

Overview

SSLSocketFactory is used to create secure sockets.

Steps to follow

• First you have to create a key store.
• Open command prompt using Administrator login.
• Type "cd C:\Program Files\Java\jdk-14\bin".
• Type the below command

 keytool -genkey -v -keystore my-key.keystore -alias my-key-alias-keyalg RSA -keysize 2048 -validity 10000

• Follow the steps given in the screenshot:

• For -keyalg you can use RSA, DSA, EC to generate asymmetric key pair or use DES, 3DES to generate symmetric key pair.
• Then you have to generate a certificate
• Open command prompt using Administrator login.
• Type "cd C:\Program Files\Java\jdk-14\bin".
• Type the below command

 keytool -certreq -alias "my-key-alias" -file mycertreq.csr -keystore my-key.keystore

• Follow the steps given in the screenshot.

• Note: The password, alias name, keystore name must be the same which you used while creating the keystore.
• An example of creating a subclass of SSLSocketFactory

 class TLSSocketFactory : SSLSocketFactory() {

    private val context = SSLContext.getInstance("TLS")
    private var delegate: SSLSocketFactory? = null
    private var protocols = arrayOf("TLSv1.2")

    init {
        context.init(null, null, null)
        delegate = context.socketFactory
    }

    override fun createSocket(s: Socket?, host: String?, port: Int, autoClose: Boolean): Socket {
        return this.enableTLSOnSocket(delegate!!.createSocket(s, host, port, autoClose))!!
    }

    override fun createSocket(host: String?, port: Int): Socket {
        return this.enableTLSOnSocket(delegate!!.createSocket(host, port))!!
    }

    override fun createSocket(
        host: String?,
        port: Int,
        localHost: InetAddress?,
        localPort: Int
    ): Socket {
        return this.enableTLSOnSocket(delegate!!.createSocket(host, port, localHost, localPort))!!
    }

    override fun createSocket(host: InetAddress?, port: Int): Socket {
        return this.enableTLSOnSocket(delegate!!.createSocket(host, port))!!
    }

    override fun createSocket(
        address: InetAddress?,
        port: Int,
        localAddress: InetAddress?,
        localPort: Int
    ): Socket {
        return this.enableTLSOnSocket(
            delegate!!.createSocket(
                address,
                port,
                localAddress,
                localPort
            )
        )!!
    }

    override fun getDefaultCipherSuites(): Array<String> {
        return delegate!!.defaultCipherSuites
    }

    override fun getSupportedCipherSuites(): Array<String> {
        return protocols
    }

    private fun enableTLSOnSocket(socket: Socket?): Socket? {
        if (socket != null && socket is SSLSocket) {
            socket.enabledProtocols = arrayOf("TLSv1.2")
        }
        return socket;
    }
 }

Reference

1. https://developer.android.com/reference/org/apache/http/conn/ssl/SSLSocketFactory
   
2. https://www.demo2s.com/android/android-sslsocketfactory-tutorial-with-examples.html
   
3. https://stackoverflow.com/questions/57409304/keytool-generate-aes-public-private-key-pair
   
4. https://stackoverflow.com/questions/3997748/how-can-i-create-a-keystore