Mutual Authentication in Selenium

A simple piece of code that uses LittleProxy as a Man-In-The-Middle proxy to be used by e.g. Selenium to connect to servers that require client side certificate, working around the problem of WebDriver not exposing any APIs to select one. To use it, create a proxy server, feed it a client certificate the server accepts and a server certificate the client trusts, then configure WebDriver instance to use it.

See a full, self-contained example here.

Basic usage:

File clientCertFile = ...;        // client cert as .p12
char[] clientCertPassword = ...;  // key password 
File serverCertFile = ...;        // PEM file
File serverKeyFile = ...;         // PEM file

org.littleshoot.proxy.impl.DefaultHttpProxyServer.bootstrap()
		.withName(clientCertFile.getName())
		.withPort(5555)
		.withAllowLocalOnly(true)
		.withManInTheMiddle(new MutualAuthenticationCapableMitmManager(
				usingPKCS12File(clientCertFile, clientCertPassword), 
				usingPemKeyPair(serverCertFile, serverKeyFile)))
		.start();

org.openqa.selenium.Proxy proxy = new Proxy();
proxy.setSslProxy("127.0.0.1:5555");
proxy.setNoProxy("<-loopback>"); // overwrite the default no-proxy for localhost, 127.0.0.1

FirefoxOptions options = new FirefoxOptions();
options.setProxy(proxy);
WebDriver driver = new FirefoxDriver(options);