A secure socket layer (SSL) certificate, Currently Transport Security Layer (TLS) certificate, is a small cryptographic technology applied in encrypting data and communications between web servers and web browsers. But I am sure you already know what an SSL Certificate is. I am also sure you understand its significance, particularly in protecting web applications against the rising menace of cyber attacks.
When people talk of TLS certificates, they often refer to server certificates. As the name implies, server certificates are essential in authenticating servers to clients. Typically, this is the standard way of authentication. But have you ever wondered how it would be when you wanted to authenticate the client to the browser? This is where 2 Way SSL (or two-way SSL if you like) comes into sight. Wondering what that is and how it works? Wonder no more! In our endless quest to simplify all complex tech-related topics, we will break down everything for you by telling you what a two-way SSL certificate is and how it works.
To better understand a two-way TLS certificate, it would be best to start by looking at the working of SSL authentication.
A Brief Overview of How TLS Certificate Authentication Works
- First, the owner of a website purchases an SSL certificate for their website domain/s. The website owner then sends an unsigned certificate together with the associated public keys to the certificate authority.
- The certificate authority is mandated to ascertain the validity of the person requesting the certificate and confirm domain ownership. The technical process for this is the Validation process. Suppose the certificate authority validates domain ownership and the requestor’s authenticity successfully. In that case, it will proceed to issue the certificate, attach the public key of the servers to the SSL certificate and sign it with its intermediate root certificate.
- The SSL Handshake process will occur whenever a web visitor tries connecting to a website via a web browser. Upon completion of the SSL handshake process, the browser will generate a session key and use the public key tied to the SSL certificate to encrypt sessions. The server would apply the private keys in decrypting encrypted sessions.
The main reason why it was important to look at how SSL authentication works were to bring out the concept of the SSL handshake (which is why I bolded it). You should note that the two differentiating factors between one-way and 2 way SSL is the SSL handshake process and the type of SSL certificate used.
Now that you have a clear understanding of the process let us now proceed to look at what a two-way SSL certificate is and how it works.
2 Way SSL Authentication
Sometimes referred to as mutual certificates, 2 way SSL certificates are applied in a situation where the server and the client (web visitors) need to authenticate one another for unquestionable security.
The two-way SSL certificate not only validates the web server (as is the case for one-way SSL certificates) but also web browsers. Both of these identities would be verified during the SSL handshake process.
The following are the steps involved in the two-way SSL handshake process.
- For a web visitor using a browser to access a website, the web browser will try to establish a secure HTTPS connection with the website servers. The browser will send the supported cipher suites to the website servers.
- The server will respond to its request by sending its SSL/TLS certificate to the web browser (client’s end).
- The browser will then need to establish the authenticity and legitimacy of the SSL certificate to confirm that it is genuine. For instance, the browser must confirm that the SSL certificate is up to date, not revoked, configured appropriately, and supports the latest algorithms. The validation process continues by the browser checking the pre-installed root store of the certificate authority to ascertain that the attached signature is genuine.
- Upon successful verification of the website servers, the client (users’ browser) will send its public certificate to the server. It is now the turn of the server to validate the validity of the certificate authority’s signature and the SSL certificate presented by the web browser.
- If all these requirements are met, the SSL handshake process is completed, and the browser generates the session keys.
As you would notice, there are additional steps in the two-way SSL handshake process. Unlike the one-way SSL process, the two-way SSL handshake process entails the browser sending its public key to the server. The server will then need to verify the validity of the signature of the certificate authority. These steps are not covered in the one-way SSL authentication.
Here are some of the most crucial elements of the two-way SSL authentication process;
- A private key
- Root certificate
- An intermediate certificate of the certificate authority
- A personal authentication certificate
The Significance of the Two-Way Certificate
You now understand what a two-way SSL certificate is, how it works and how different it is from the one-way SSL certificate. The next issue to address will be the significance of the two-way SSL certificate. You are probably wondering, “is a two-way SSL certificate really necessary?”
You should understand that a website uses two-way authentications to choose the clients it wants to interact with without putting its security at stake. Take the instance of an entity’s intranet website that typically exists to aid employees within the organization in communicating with other organizational stakeholders.
The organization does not want outside parties to access its intranet network and would love to keep it as restricted as possible.
To further address the risk of unsolicited threats, stakeholders should be required to only access the network from work devices and not their own gadgets. Such as a case that needs the application of a two-way SSL certificate that is necessary for the authentication of clients before allowing them to access the network.
Organizations can also leverage two-way SSL certificates to help them protect their websites against unauthorized access and infiltration of dangerous bots.
Where is the Two-way Certificate Authentication Most Suited?
Two-way SSL certificates are most suitable in circumstances where a website owner wants to restrict website access to specific users. Organizations wishing to mitigate financial fraud and other cybersecurity threats should employ two-way SSL certificates.
To Sum It Up
The whole aspect of SSL certificates is often diversified and full of technical jargon that regular internet users might not be able to understand.
For instance, the aspect of a 2-way SSL certificate can be new to most people. But it is important for you to understand such concepts, especially if you are in the cybersecurity industry.
This article has given you a headstart by explaining what a two-way SSL certificate is and how it works.
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