SSL vs TLS. What Is the Difference Between SSL and TLS Certificates?

SSL and TLS are interchangeable acronyms when put next to the “certificate” term, but fundamentally, they are different cryptographic protocols designed to perform the same task. In this ultimate SSL vs TLS guide, we’ll have a closer look at each protocol and its distinct features so that you know the difference between SSL and TLS.

Before we dive deep into the technicalities of SSL and TLS, let’s take a birds-eye view of the entire SSL industry and see why it plays a crucial role in today’s web security.

Table of Contents

1. What are SSL/TLS certificates?
2. A short history of SSL/TLS certificates
3. What is the difference between SSL and TLS certificates?
4. What is the difference between SSL and TLS encryption?
5. Which is more secure, SSL or TLS?
6. If SSL is now TLS, why aren’t we calling them TLS Certificates?

What Are SSL/TLS Certificates?

An SSL/TLS certificate is a small digital file that secures sensitive data in transit between two computer applications over a network. And, since the Internet is the largest computer network, SSL certificates are an essential element of any website.

By default, all the information users share with a website travels in plain text from the browser to the web server over HTTP (Hypertext Transfer Protocol). This client-server protocol is vulnerable to cyber threats, particularly man-in-the-middle attacks that can intercept and steal sensitive details such as credit card numbers. To prevent this, computer scientists invented the SSL and TLS protocols, which digital certificates follow. Here’s how it all works in practice:

Let’s say you have an online store that sells crystals. When customers arrive at your checkout page, they fill in the payment details and click the buy button. Now, all their info goes directly from their browser to your server. If HTTPS protocol is enabled, to a potential hacker, the data will look like a string of random characters instead of the actual names, addresses, and credit card numbers.

Breaking the SSL/TLS encryption is beyond human capabilities. That’s why SSL certificates are now mandatory for every site. Without one, browsers will flag connections as not secure. What’s worse, the site won’t appear in the search engine results pages.

How do you obtain an SSL Certificate? You get it from a Certificate Authority, a third-party entity that validates domain ownership and, if required, company legal status. Next, you install/upload the certificate files on your website’s server and activate the secure HTTPS protocol. That’s it! Your website is secure, and users’ data is safe.

A Short History of SSL/TLS Certificates

The 90s gave us the very first websites and browsers and the first secure retail transaction over the Web. But, as is often the case of early releases, the initial version of SSL (Secure Sockets Layer) was teeming with vulnerabilities. It was so weak that it never went live.

In 1995, Netscape released SSL 2.0 for general use and, one year later, the enhanced SSL 3.0 protocol. Still not happy with the security performance, Netscape joined forces with its competitor Microsoft in 1999 and developed a brand-new cryptographic protocol called TLS (Transport Layer Security).

TLS 1.0 was almost identical to SSL 3.0, but with each new release, it became more secure. TLS 1.2 is soon-to-be 15 years old but still widely used today. The latest TLS 1.3 version offers the most improvements and is now steadily implemented across the Web.

Now that we’ve briefly covered the SSL and TLS history, let’s see what are their similarities and differences.

What Is the Difference Between SSL and TLS Certificates?

To the average user, SSL or TLS doesn’t mean much. As long as the padlock icon is next to a website’s URL, using it is safe. Nor should you be worried about SSL vs TLS certificates when buying one. It’s important to distinguish between certificates and protocols.

The certificates are the digital files that authenticate your server identity so browsers can establish a secure connection through cryptographic protocols. These communication protocols enable two parties to exchange data with privacy and integrity.

Today, most sites support TLS 1.2 and TLS 1.3 protocols, while the SSL versions are no longer in use. Technically, everyone is using TLS certificates, regardless of what we call them. So when we refer strictly to certificates, there isn’t a difference between SSL and TLS in 2023. As for protocols, with every new TLS release, the SSL predecessor became obsolete.

What Is the Difference Between SSL and TLS Encryption?

When we compare SSL vs TLS, encryption is just a part of the handshake between a client and a server. SSL 2.0 used the RSA (Rivest Shamir Adleman) key exchange only, while SSL 3.0 and TLS versions also support the Diffie-Hellman (DH) one. TLS 1.2 introduced support for Elliptic Curve Cryptography, while in TLS 1.3, RSA has been removed.

All these encryption techniques use complex algorithms called cipher suites to convert the original plaintext message to an encoded ciphertext, but they have one thing in common: public key cryptography.

Public-key cryptography or asymmetric cryptography uses different keys to encrypt and decrypt data. Here’s how it works:

Suppose John wants to send a secret message to Jane. Jane has both a public and a private key, so she keeps her private key in a safe place and sends her public key to John. John encrypts the secret message using Jane’s public key. Jane can later decrypt it with her private key. But what if Tom masquerades as Jane? How will John trust Jane? Enter digital signatures and Certificates Authorities (CAs).

The SSL/TLS certificates are digitally signed by a CA that creates the signature using its private key and provides identification for the bearer, in our case, Jane.

As you can see, both SSL and TLS protocols try to accomplish the same thing, but with each new TLS release, the approach and security advancements far differ from the early SSL versions.

TLS, for instance, uses fewer cipher suites but more efficient ones that leave no room for hacking. The cipher suites provide Perfect Forward Secrecy (PFS) and accept any key length. On the other hand, SSL supports only one cipher suite with PFS, which uses a 1024-bit RSA key.

Arguably the biggest difference between SSL and TLS is message authentication. SSL employs message authentication codes (MACs) to ensure message integrity during transmission. TLS does not use MACs but instead relies on encryption to prevent tampering.

Which Is More Secure, SSL or TLS?

As the Internet evolved and cyber threats became more prevalent, the old SSL protocols were too weak to face the onslaught of attacks. The first SSL version didn’t even go live, and the next release wasn’t a finished product either. SSL 3.0 came to fix the flaws of its predecessor, while the first two TLS releases brought only minor changes.

Significant improvements came with the arrival of TLS 1.2, while TLS 1.3 took them to a new level, redefining some of the core concepts. Today the SSL protocols are deprecated and no longer supported by most servers and clients. You may still find SSL enabled on some legacy platforms, but the Internet has moved on to TLS 1.2 and 1.3.

SSL Vulnerabilities and POODLE

In 2014, a team of security specialists employed by Google detected a critical issue in SSL and called it POODLE (Padding Oracle On Downgraded Legacy Encryption). This discovery sparked a massive transition from SSL to TLS.

In a nutshell, POODLE takes advantage of SSL 3.0 fallbacks. The attackers abuse the SSL protocol and use it to decrypt parts of the content. By doing a significant number of attacks, hackers were able to reveal some bits of the connection between the client and the server and access the information. Any system that supports SSL 3.0 can be breached using the POODLE method.

In 2002, long before the POODLE vulnerability, other SSL loopholes such as BREAST or BREACH came to light. It was only in 2011 that these attacks were proven to be a real issue. Microsoft, Apple, and other browser companies worked together to eradicate them. Eventually, all these security breaches were the reason why SSL was replaced by TLS.

Back then, the quickest fix to any SSL vulnerabilities was to disable the protocol from the server side and use only the secure TLS 1.2 version. Today, many users still ask what is better, SSL or TLS? The answer is obvious, and it’s been the same for over a decade. TLS  is the more stable protocol, with advanced security features able to cope with modern cyber threats. SSL is the past, while TLS is the present and future.

If SSL Is Now TLS, Why Aren’t We Calling Them TLS Certificates?

The difference between SSL and TLS becomes more significant as the years pass and new TLS releases adopt high-end encryption technologies. When TLS first emerged as an alternative to SSL, it brought minor changes, and some servers didn’t support it. To avoid technical confusion, everyone kept using the old SSL acronym for connections over the SSL 3.0 protocol.

During the peak of SSL vulnerabilities, hackers had fun downgrading the TLS protocol to SSL 3.0 via the previously mentioned POODLE attack. Tired of its constant flaws, the industry regulators deprecated the SSL protocol but kept the name for marketing purposes.

Since the general public is familiar with the SSL term, the leading Certificate Authorities, such as DigiCert, GeoTrust, RapidSSL, Thawte, and Sectigo, use it on all their products.

Will we ever get rid of the SSL acronym and use TLS exclusively? Considering that it’s now eight years since SSL 3.0 is history, and there are no signs of CAs removing the SSL name, the old three-letter abbreviation will remain in place for the foreseeable future.

Final Thoughts

The SSL vs TLS question will be on every user’s mind when they first learn about SSL certificates and the encryption of sensitive data. Both cryptographic protocols solve the same problem, but as is often the case with technology, the initial releases contain shortcomings that only future alternatives can overcome.

The SSL protocol has paved the way for a better, faster, and more reliable TLS option. And that’s the main difference between SSL and TLS. With every new TLS release, the similarities wane and diverge. To sum up the entire article in one sentence: All SSL certificates are now TLS certificates with the old acronym attached for clarity and user-friendliness.

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Written by Dionisie Gitlan

Experienced content writer specializing in SSL Certificates. Transforming intricate cybersecurity topics into clear, engaging content. Contribute to improving digital security through impactful narratives.