VERIGRITY GUIDE

SSL vs TLS: What Is the Difference?

By T.O. — Independent Remote Researcher

Most people say "SSL certificate" when they mean a TLS certificate. Most tools show a padlock labelled "SSL." The naming is decades out of date. Here's what SSL and TLS actually are, how they differ, and why the confusion persists — and whether any of it matters for how you check a website.

The short answer

TLS (Transport Layer Security) is the modern encryption protocol that secures the connection between your browser and a website. SSL (Secure Sockets Layer) is the older protocol it replaced. Nobody uses SSL anymore — it was deprecated in the late 1990s and formally disabled in major browsers by 2015. But the name "SSL" stuck, and it's still used everywhere: in marketing, in product names, and often in the browser UI itself.

So when someone says "SSL certificate" today, they almost always mean a TLS certificate — the certificate used to authenticate a TLS connection. The two terms are used interchangeably, but they refer to different generations of the same technology.

A brief history

SSL 1.0 was never released. SSL 2.0 shipped in 1995 with Netscape Navigator. It had serious design flaws. SSL 3.0 arrived in 1996 and fixed most of them — but by then the internet had moved on, and a redesign was underway.

In 1999, the IETF published TLS 1.0 as the successor to SSL 3.0. TLS 1.0 was similar enough to SSL 3.0 that the two protocols are sometimes called "SSL/TLS" together, but they are technically distinct, incompatible, and not interchangeable.

Further versions followed:

• TLS 1.0 (1999) — deprecated in 2021
• TLS 1.1 (2006) — deprecated in 2021
• TLS 1.2 (2008) — still in widespread use, still secure when configured well
• TLS 1.3 (2018) — the current standard, faster and simpler than 1.2, removes obsolete cryptographic primitives

By 2020, TLS 1.3 accounted for a large share of all HTTPS traffic. Major browsers and cloud providers have been enabling it by default since it was published.

What actually changed

TLS and SSL share the same high-level architecture: a handshake to establish a shared secret key, then symmetric encryption of the traffic using that key. Where they differ is in the details — and those details matter for security.

• Handshake design. TLS 1.3 cuts a full handshake down to one round trip (or zero, for resumed sessions), which is noticeably faster than SSL 3.0's multi-step dance.
• Cryptographic primitives. SSL 3.0 supported ciphers (RC4, MD5-based constructions, etc.) that are now known to be weak. TLS 1.3 only supports ciphers that are secure by modern standards.
• Forward secrecy. TLS 1.3 makes forward secrecy mandatory for every session. If a server's private key is later compromised, previously-recorded sessions cannot be decrypted. SSL 3.0 offered no such guarantee.
• Attack surface. SSL 3.0 had design-level vulnerabilities — most famously the POODLE attack (2014) — that made it unsafe to enable at all. TLS 1.3 removed entire classes of features (renegotiation, compression, custom cipher negotiation) to eliminate similar bugs.

Modern browsers disable SSL entirely. If a server tries to negotiate SSL 3.0, the browser refuses and shows a connection error.

Why we still say "SSL"

Three reasons:

1. Marketing inertia. Certificate Authorities have sold "SSL certificates" for 25 years. "TLS certificate" never caught on in commerce, even though it's technically correct.
2. The padlock in your browser. For years, browsers labelled the padlock "SSL." Even today, clicking it in some browsers still shows "SSL certificate." Browsers have been slow to rename it.
3. Search volume. Far more people search for "SSL certificate" than "TLS certificate." Companies name products to match user vocabulary.

The result is that "SSL" is now a generic term, like "Kleenex" or "Xerox." It's technically incorrect, but widely understood to mean the modern protocol.

Does any of this matter when you check a website?

Not really — but there are two cases where the distinction shows up in practice:

1. Very old servers

If a site's server only supports SSL 3.0 or TLS 1.0, modern browsers refuse to connect at all. So if a site loads in your browser, it's using at least TLS 1.2. You don't need to worry about "the site might be using SSL."

Where it matters is when a security scanner flags a site for supporting a deprecated protocol. If a site still accepts TLS 1.0 connections (for compatibility with old clients), a scanner will report it as a weakness. This is common on older infrastructure.

2. Cipher suite configuration

The protocol version is only half the story. Even on TLS 1.2, a server can support ciphers that are considered weak — for example, ciphers without forward secrecy, or ciphers using SHA-1 for message authentication. A well-configured server restricts itself to modern ciphers. A poorly-configured one accepts anything.

Most public TLS checkers (including Verigrity's) verify the protocol version and validity of the certificate but don't deeply test cipher configuration. For a deeper audit, use a dedicated tool like SSL Labs' server test.

What a modern TLS certificate contains

Even though it's called a "TLS certificate," the certificate itself is an X.509 document. It contains:

• The subject — the domain the certificate was issued to.
• The issuer — the Certificate Authority that signed it.
• The public key — used during the handshake.
• The validity window — "not before" and "not after" dates.
• Optional extensions — such as Subject Alternative Names (additional domains the certificate covers).

The certificate is not protocol-specific. The same X.509 certificate can be used with TLS 1.2 or TLS 1.3. It just describes who the server claims to be.

Frequently asked questions

Is SSL still used?

No. SSL 2.0 and 3.0 are disabled in all modern browsers, and no reputable Certificate Authority issues SSL-era certificates. When you see "SSL" today, it's almost always a misnomer for TLS.

Should I buy an "SSL certificate" or a "TLS certificate"?

They're the same thing. Any certificate you buy today will be used with TLS. The vendor's choice of wording doesn't affect what you get.

Is TLS 1.2 still secure?

Yes, when configured with modern cipher suites. TLS 1.3 is preferable — it's faster and removes more legacy options — but TLS 1.2 remains secure and widely deployed.

How do I know which version a site uses?

Most browsers don't show this by default. On Chrome, open Developer Tools → Security tab, which shows the negotiated protocol. Or use a dedicated TLS checker like the Verigrity TLS Certificate Checker, which fetches the certificate and reports the issuer, subject, and validity window.

Does the protocol version affect whether I should trust a site?

Only weakly. A site on TLS 1.3 is well-configured. A site on TLS 1.2 is normal and fine. A site that refuses HTTPS entirely is a problem. But protocol version alone doesn't tell you whether the business is honest — for that, you need to look at other signals.

Run the TLS Certificate Checker

← Browse all Verigrity guides