TLS vs SSLWhat’s The Difference Between SSL and TLS Certificates?

With high-profile data breaches making headlines around the world, website security vulnerabilities have become a more prominent topic of concern. This shift has made clear the need for laypeople to understand TLS and SSL certificates and the cryptographic protocols that underpin them. The ability to recognise certificate-specific security flaws such as deprecated SSL protocols, private key breaches, and web server configuration problems has become an absolute necessity. Individuals or businesses who run a website should know why the improvements and security enhancements offered by TLS (Transport Layer Security) over SSL (Secure Sockets Layer), such as stronger hash algorithms and forward secrecy, have made TLS the standard protocol for secure communication.

Modern SSL certificate products use Transport Layer Security (TLS), which is the successor to the outdated Secure Sockets Layer (SSL) technology. So, the SSL certificates you can buy today are, in truth, TLS certificates. SSL and TLS protocols are intertwined by necessity, coexisting to form the baseline of every secure connection on the internet. If you don’t already know, SSL or TLS certificates are installed on websites to secure communication between users and the server, encrypt data during transmission, and protect sensitive information (like credit card information and passwords) from unauthorised access.

This article aims to take you through the basic information that you need to know about modern cryptographic protocol technologies. In short order, it will explain how the TLS vs SSL comparison works, how SSL and TLS protocols interact with one another, and how contemporary SSL certificates leverage said technologies to establish a secure connection over a given SSL handshake.

Because every SSL certificate is, in fact, a TLS certificate, there’s really not much point in comparing the two. This would be like comparing videotapes to DVDs. DVDs are superior in every way, such that videotapes are no longer commercially produced. This is basically the case when it comes to TLS vs SSL.

The SSL certificates users can buy and implement on their websites today use a modern TLS version that resolves various security flaws that had been present in historical SSL protocols. These cipher suites are, therefore, far beyond the scope of any old SSL protocol.

For ease of reference and practicality, however, SSL and TLS protocols have been unified under the umbrella of SSL/TLS certificates. This interaction between the two types of secure communication solutions may not describe the exact nature of their respective security certificates and the underlying handshake process, but it does serve a purpose in correlating the two technologies against one another. The key exchange methods in these protocols are crucial for establishing a secure encrypted connection between clients and servers, with the choice of encryption algorithms directly influencing the overall security.

Before moving on, let us explain the background of both SSL and TLS protocols in separate contexts.

The presence of inherent security flaws in web server implementations was made apparent very early on, in the nascent stages of the internet. Some of the first major attempts to tackle serious security flaws were made by a company called Netscape, which also ended up producing the very first version of Secure Sockets Layer cipher suites.

Interestingly, SSL 1.0 never ended up being released publicly. According to authoritative sources on the matter, the issues inherent to this early-stage SSL protocol were unfixable, though the premise of using cipher suites as a baseline for a universal cryptographic protocol was sound.

To that end, Netscape quickly moved on to working on SSL 2.0, which was released into the World Wide Web back in 1995. It is worth pointing out that SSL 2.0, while superior to SSL, wasn’t without fault. Substantial problems with the second rendition of the Secure Sockets Layer technology were identified almost as soon as it was released, but the mere presence of any type of web server security quickly proved to be well worth the trouble.

Namely, SSL 2.0 was limited exclusively to using the MD5 message-digest algorithm - a 128-bit hash function that was cryptographically broken very early on - and employs the same key for both message authentication and encryption. On top of that, SSL 2.0 only allowed the client and server to send one public key certificate to another, which meant that each certificate needed to be signed directly by a trusted root certificate authority.

While SSL 2.0 may have been a clumsy solution, it still provided some amount of security to webmasters around the world.

In fact, it wasn’t until 2011 that SSL 2.0 would finally be deprecated in lieu of the significantly more robust SSL 3.0 protocol. Though its earliest draft came out way back in 1996 - as a response to criticism directed at its predecessor - the technology wouldn’t be completely phased out until years later when vulnerability became too much for the budding internet cyberspace.

Funnily enough, the baseline Secure Sockets Layer technology would finally be grinding to a halt only three years later, in 2014. SSL 3.0 was proven to be remarkably vulnerable to the then-novel POODLE attack (i.e. Padding Oracle On Downgraded Legacy Encryption), which allowed attackers to make just 256 requests to unravel a single byte of a given encrypted message.

This massive fault in SSL 3.0’s implementation of symmetric encryption would lead to the development of the TLS handshake or the substantially improved version of digital certificates that would eventually solve the vast majority of then-relevant security concerns on the internet.

Though it wouldn’t be officially launched until 2014, the basics of Transport Layer Security (TLS) were put down a decade and a half earlier by the aptly named Internet Engineering Task Force (IETF) in 1999. TLS version 1.0 was designed as a direct upgrade and success to SSL 3.0, with differences between the two cipher suites being relatively minor yet significant enough to completely disregard any odds of interoperability.

After SSL 3.0 was finally retired, Transport Layer Security (TLS) effectively took over all new handshake process instances from that point on. Any SSL version was made legacy, with the only way to secure server configurations in a post-SSL 3.0 world being to rely on the latest TLS protocols.

Following TLS 1.0, the development of the newly established Transport Layer Security protocol progressed relatively quickly.

TLS 1.1, for one, was defined in 2006 and wouldn’t be deprecated until very recently in 2020.

TLS 1.2 got its outline in 2008, introducing support for SHA-256 and optional PRFs specified by the cipher suite, as well as a comprehensive support portfolio for authenticated encryption ciphers.

For more, see our ultimate guide to TLS to learn more about how exactly it improves on SSL.

The latest version of TLS - TLS 1.3 - is still in its adoption stages. However, the rollout of TLS 1.3 has significantly gained momentum in 2024. Initially slow to replace its predecessor, TLS 1.2, TLS 1.3 is now being widely implemented across various platforms and industries. Major organisations like Microsoft, Oracle, and Azure have embraced TLS 1.3 to align with evolving industry standards and improve security and performance.

Azure API Management began rolling out TLS 1.3 support in early 2024, completing availability for all customers by March.

Oracle Database 23c now supports TLS 1.3, offering automatic and transparent implementation for most users.

Azure Cosmos DB enabled TLS 1.3 on all public endpoints in October 2024, coinciding with the deprecation of TLS 1.0 and 1.1 on October 31, 2024.

In line with government mandates, the National Institute of Standards and Technology (NIST) instructed all U.S. Federal Agencies to support TLS 1.3 by January 1, 2024.

Going into 2025, the transition to TLS 1.3 is becoming more pronounced, with some organisations planning to deprecate older versions. For example, MIDAS has proposed dropping TLS 1.2 support in early 2025 to make way for TLS 1.3.

Time will tell how rapidly TLS 1.3 overtakes TLS 1.2 in mainstream web security.

For all intents and purposes, SSL technology is nowadays referenced simply due to semantics. It is the predecessor to the actual modern cipher suites, and all modern encryption keys supersede all legacy SSL digital certificates in every way that matters.

We still do refer to SSL certificates as such, however, with SSL/TLS being the preferred umbrella term when it comes to discussions of what is, effectively, a matter of Transport Layer Security (i.e. TLS certificate products) and little else.

An interesting tidbit of SSL certificate trivia is that there is, in fact, a curious reason why the world of PKI didn’t continue using Secure Sockets Layer terminology - presumably with a hypothetical SSL 4.0 - but chose to rebrand as Transport Layer Security, instead.

According to Tim Dierks, one of the writers of TLS 1.0, the introduction of an entirely new nomenclature for what is, effectively, a continuation of existing terminology was part of the discussions between Microsoft and Netscape back in the mid-90s.

Back then, Netscape and Microsoft were essentially developing competing cipher suite solutions for different web browsers, and the two super-companies needed to come to a unified, secure communication solution before further bifurcation of standards.

TLS 1.0 was, at the time, known as SSL 3.1, but the only way to get Microsoft to forego their own tech in lieu of something standardised was to get rid of Netscape’s naming scheme. Namely, the company in charge of these discussions - Consensus Development, where Dierks then worked - was attempting to change SSL 3.0 so it wouldn’t look like Microsoft was simply re-titling the SSL certificate protocol that Netscape had come up with.

As it turned out, one of the main publicly visible changes was the revamp of the naming scheme. That’s how SSL 3.1 became TLS 1.0. Simple, yet effective.

Of course, it’s always worth remembering that the introduction of new security standards - such as the jump from SSL 3.0 to TLS 1.0 - doesn’t mean all that much if certificate authorities don’t adapt their products accordingly.

Studies have shown that numerous root authorities yet fail to implement valid SSL/TLS functionality in their SSL certificate products.

Of course, this is just the reality of the current SSL certificate market - users ought to be aware of the products they’re investing in. The issues implied by the given study relate to the topic at hand simply as an additional contextualisation of the otherwise complex matter of private key infrastructure and the general use of SSL certificate implementations.

Modern web browsers can host immense transitions of sensitive data, which is an invitation to malicious attackers present online. As attacks grow more complex in nature, so too does contemporary encryption strength.

Still, an awareness of the reality of these threats is very much needed, as handshake messages and cipher block chaining are no magic.

Now that all the basics are in place, the question one might want to ask is, why would anybody compare TLS vs SSL in the first place? The answer lies - more often than not - in the fact that a layperson doesn’t know the intricacies of modern SSL/TLS certificate solutions and generally doesn’t need to understand the related jargon.

To someone who’s just getting familiar with the topic of web server protection and SSL certificates, it very well could look like SSL and TLS are two competing protocols that they may be able to choose from. With the immense glut of information about modern security protocols available online, simply sifting through all the information that is available could look like an insurmountable issue.

In every way that matters in practical terminology, SSL and TLS protocols are one and the same. Much of the information we have gone through in this article should help contextualise how the technology developed, how SSL certificates have technically been replaced by the more advanced TLS certificates, and why we still use SSL/TLS verbiage even though SSL is no longer in use.

Of course, there still remains the matter of actual, literal differences between outdated SSL certificates and the more modern TLS certificates for those who are interested.

The major differences between SSL certificates and TLS certificates can be simply described by discussing five major features of any given SSL/TLS certificate. In this section, we’ll go into some detail on how these features compare the two security standards.

Simply put, there are five major areas of operation in which contemporary SSL certificates differ from legacy SSL certificates:

Note that we are simplifying things a fair bit here. The specific operation and specialisation of SSL certificates both go far beyond the scope of this shortlist. If you’re interested in learning how a given SSL certificate operates or how some TLS protocol behaves in practice, you may need to refer to specific product pages for more information.

The hash calculation that was done as part of old SSL certificates included the master secret and pad that had been prepared beforehand, whereas modern TLS certificates generate their master secret on the fly using a pseudo-random function.

In SSL certificates, message authentication was conducted ad-hoc, using both key information and application data all at once. TLS protocols, instead, use HMAC, which is essentially a standardised message authentication code.

TLS removed support for the Fortezza cipher suite from the get-go, opting instead for the much-improved standardisation process, allowing the introduction of entirely new cipher suites. These include, but are not limited to, AES, IDEA, RC4, and others. SSL certificates simply did not have this capability.

TLS certificates use HMAC after every message encryption, while SSL certificates use bog-standard MAC to do the same job. This means SSL lacks the additional cryptographic protocols that HMAC’s hash functionality now provides by default.

While old SSL certificates only support a single, mostly nondescript “no certificate” error message, TLS certificates instead feature a wide variety of alert messages. This difference in alert messages highlights how TLS allows for significantly easier diagnostics and problem-tracking in regard to network security.

By now, it should be plenty obvious that comparing TLS vs SSL isn’t, in fact, something anyone should do in practical terms. In terms of historical SSL certificate development, however, there is certainly merit in seeing why there wasn’t a direct successor to SSL 3.0 and why modern web browsers generally employ both SSL and TLS protocol to ensure a safe browsing environment.

The topic of TLS vs SSL comparisons, for the most part, seems to be derived from a lack of understanding of how SSL and TLS function and the manner in which every modern TLS protocol is, in fact, derived from legacy SSL implementations.

The SSL certificates webmasters have access to today go far and beyond the original SSL and TLS implementations as they were first envisioned. Whether it’s in regard to features or sheer security management functionality, TLS versions 1.2 and 1.3 are solid ways to encrypt data on the cheap, with certificate authorities constantly working to improve encryption strength and the handling of TLS handshakes in their SSL protocols.