Before jumping on to the example, first let us see What is SSL Certificate and When do we get UNTRUSTED CONNECTION Alert / Error.

Firstly, WHAT IS SSL CERTIFICATE ?

SSL is used to keep sensitive information which is sent across the Internet encrypted so that only the intended recipient understand it. This is important because, the information that we send on the internet is passed from one system to other system to the destination server.

If it is not encrypted with an SSL certificate, any computer in between you and the destination server can see your private information such as credit card numbers, usernames, passwords and other sensitive information.

When an SSL certificate is used, the information will be encrypted and it will ensure that you are sending information to the right server and not to a criminal’s server.

WHEN DO WE GET UNTRUSTED CONNECTION ERROR

When ever you try to visit a website whose web address starts with https, your communication with this site is encrypted to ensure your privacy. Before starting the encrypted communication the website, you will be presented with a "certificate" to identify itself.

The certificate helps to determine whether the site you are visiting is actually the site that it claims to be. If there is any problem with the certificate, you will see an alert saying 'This Connection Is Untrusted'. What it means is that browser (Firefox/Chrome etc) isn't able to verify the identity of the website, there can be several problems which can cause browser to reject a certificate.

This is how the error looks like :

The below are the common errors that we see :

1. Certificate will not be valid until (date)

Error code: sec_error_expired_issuer_certificate
This error can occur if our system clock has the wrong date, check error message which will be in the past. We can fix this problem, by setting system clock to current date.

2. Certificate expired on (date)

Error code: sec_error_expired_certificate
This error occurs when a website identity certification has expired. This can also occur if system clock has the wrong date. We can fix this problem, by setting system clock to current date.

3. Certificate is only valid for (site name)

Error code: ssl_error_bad_cert_domain
This error says that the identification sent to you by the site is actually for another site. While anything you send would be safe from eavesdroppers , the recipient may not be the same who you think it is.

The above listed errors are the common errors, you may come across other errors which actually depends on the websites that you access.

Now Let us see how to handle SSL Untrusted Connection and Accept with Selenium webdriver. Let me try to do with Firefox browser first and then we will go with other browsers.

We will create new firefox profile and set 'setAcceptUntrustedCertificates' as true and setAssumeUntrustedCertificateIssuer as false.

package com.example;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.firefox.FirefoxProfile;
import org.testng.Assert;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class SSLExample {
	
	private WebDriver driver;

	@BeforeClass
	public void setUp() {
		//Creating new Firefox profile
		FirefoxProfile profile = new FirefoxProfile();
		profile.setAcceptUntrustedCertificates(true); 
		profile.setAssumeUntrustedCertificateIssuer(false);
		driver = new FirefoxDriver(profile); 
		driver.manage().window().maximize();
	}
	
	@Test
	public void openApplication() {
		System.out.println("Navigating application");
		driver.get("https://cacert.org/");
		WebElement headingEle = driver.findElement(By.cssSelector(".story h3"));
		//Validate heading after accepting untrusted connection
		String expectedHeading = "Are you new to CAcert?";
		Assert.assertEquals(headingEle.getText(), expectedHeading);
	}
	
	@AfterClass
	public void tearDown() {
		if(driver!=null) 
			driver.quit();
	}
	
}

Done. You have now accepted the SSL Certificate with Selenium webdriver.

To work with Chrome and IE, You can check the example here to Handle SSL certificates in Chrome and Internet explorer

Happy Selenium.

Let us know if you face any issues encounter when working. We will try to figure it out.

Thank You.