SSL vs. TLS: The Difference between Communication Protocols

SSL and TLS are two communication protocols that help protect our data. But what exactly do they do, and what sets them apart?

You’ve seen “HTTPS” in website URLs before. The extra “S” stands for “secure” and means that communication between your device and that website is encrypted through SSL or TLS. This prevents hackers from stealing information as it travels across the Internet.

In this guide, we’ll explore what SSL and TLS are, how they work, the key differences between them, and why the newer TLS protocol is more secure. We’ll also explain how web hosting providers handle these protocols.

What Are SSL and TLS?

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over the Internet. They use encryption algorithms to scramble data into coded messages that only the intended recipient can decipher.

When you install an SSL/TLS certificate on your web server, it creates a public key and a private key. These keys authenticate your server and allow it to encrypt and decrypt data through a mathematical formula.

So SSL and TLS have the same purpose – to create secure internet connections. One is just newer and more improved (we’ll get to that). First, let’s explore the history and versions of each protocol.

SSL Protocol

Netscape developed the SSL protocol in the mid-1990s to secure data transmission between web browsers and servers. Unfortunately, the first two SSL releases had security flaws:

• SSL 1.0 was never made public due to vulnerabilities
• SSL 2.0 had multiple issues and was deprecated (phased out)
• SSL 3.0 arrived in 1996 and fixed the problems found in SSL 2.0

However, almost 20 years later, researchers uncovered a major vulnerability called POODLE that affected SSL 3.0. This attack allowed hackers to use the fallback of SSL 3.0 to decrypt sensitive information.

As a result, it was deprecated as well.

The Internet Engineering Task Force (IETF) was then tasked to find a solution. It created the TLS protocol to improve upon SSL 3.0.

TLS Protocol

TLS 1.0 was released in 1999 as an upgrade of SSL that still contained a few vulnerabilities.

Later TLS versions addressed these flaws:

• TLS 1.1 (2006): Added protection against CBC attacks
• TLS 1.2 (2008): Major security and performance upgrades
• TLS 1.3 (2018): Faster and more secure than previous TLS versions

In summary, the TLS protocol evolved from SSL 3.0 to offer better website encryption through faster, more secure connections. To clarify this, let's look at the key differences between the two technologies.

Key Differences between SSL and TLS Protocols

SSL and TLS may seem similar on the surface since they both enable encrypted data transfer. But when you peek under the hood, some important distinctions arise. TLS has important security, speed, and capability advantages that have made it the industry standard.

Here are some of the main distinctions.

Security

Unfortunately, researchers discovered several vulnerabilities in older SSL versions that attackers could leverage to decrypt sensitive communications. We already mentioned the POODLE attack, which allows hackers to decrypt SSL 3.0 connections.

Another example is the BEAST attack. This one also decrypts data sent over SSL and TLS connections. It does so by targeting weaknesses in the Cipher Block Chaining (CBC) encryption method used.

Each TLS version adds layers of protection against new threats. TLS 1.3, the latest release, significantly improves security through upgraded encryption algorithms. It also removes outdated cipher suites like SHA-1 and RC4. Overall, TLS does a better job of safeguarding information.

Handshake Process

The handshake process establishes a secure client/server connection through encrypted key exchanges. SSL handshakes require more back-and-forth communication, which slows down connections.

TLS handshakes became faster and more efficient by reducing round-trip messages. Fewer trips across the network means quicker connections and less exposure to hackers.

For reference, here is a typical handshake in TLS 1.3:

1. The server listens for incoming connections on port 443, which is the standard port for HTTPS.
2. The client initiates a connection to the server on port 443 and sends a ClientHello message. In TLS 1.3, the number of supported cipher suites has been reduced from 37 to 5. The client assumes the server will use one of these five cipher suites and preemptively generates a key pair for each. The client then sends the key pairs to the server along with the desired protocol version.
3. Upon receiving the ClientHello message, the server selects the most suitable cipher suite and calculates the session key using the client’s key share.
4. The server responds with a ServerHello message, which includes the server’s own key share. This allows the client to generate the same session key. Additionally, the server sends its encrypted SSL/TLS certificate using the session key created in step 3.
5. The client receives the ServerHello message and uses the server’s key share to calculate the session key independently. It then decrypts and verifies the server’s certificate. If everything checks out, the handshake is considered complete, and a secure connection is established.

Cipher Suites

Cipher suites are sets of algorithms that perform authentication, encryption, and data integrity checks during transactions. SSL supports outdated suites like RC4 and DES. TLS generally uses more modern and secure ciphers like AES and SHA-2. Each version removes vulnerable options and adds better ones.

Alert Messages

Sometimes, errors happen during secure sessions; alert messages communicate these issues between client and server. SSL only has two levels – warning and fatal. TLS expanded alerts to include a “close notify” message for ending connections securely.

Additionally, SSL sends unencrypted alert data, allowing hackers potentially access to sensitive information. TLS encrypts all alerts to enhance privacy.

Message Authentication

Lastly, message authentication verifies data integrity through cryptographic checksums called MACs (Message Authentication Codes). The recipient decrypts the MAC to confirm the message wasn’t altered during transit.

SSL:

• SSL uses the Message Digest 5 (MD5) algorithm to generate MACs.
• MD5 is a hash function that produces a 128-bit hash value.
• MD5 has been found to have cryptographic weaknesses and is now considered outdated/insecure.

TLS:

• TLS uses the Hash-based Message Authentication Code (HMAC) for MAC generation.
• HMAC is a more secure algorithm that combines a cryptographic hash function (such as SHA-256) with a secret key.
• HMAC provides better security and resistance against cryptographic attacks.

Relationship between SSL/TLS and HTTPS

Hopefully, you now understand how SSL/TLS protocols work. But where exactly do they fit into the bigger picture? Well, they provide the “S” for HTTPS. HTTPS is a secure version of the standard HTTP communication protocol. It protects websites through:

• Encryption from SSL/TLS protocols
• Authentication via SSL/TLS certificates

When a visitor accesses an HTTPS site, the browser checks the SSL/TLS certificate to validate the server’s identity. Valid certificates indicate it’s safe to transmit information. They are a stamp of approval, indicating that hackers aren’t impersonating legitimate sites to steal data.

SSL/TLS certificates contain identifying details like organization name, location, and server ownership. They also include an expiration date and a public key for encryption. The servers automatically renew the certificates before they expire to avoid errors. Overall, SSL/TLS certificates enable encrypted data exchange by confirming site validity.

If the certificate isn’t properly configured, the browser may display privacy errors that could scare visitors away. For instance, Google Chrome displays “HTTPS Not Secure.”

Relying on outdated SSL versions also weakens protection against modern hacking strategies.

SSL vs TLS: Which Should You Use?

Given the vulnerabilities in SSL protocol, TLS is universally recommended for secure online communication. All modern browsers and servers now support some version of TLS or another. In fact, many have even deprecated SSL support due to inherent flaws.

However, website owners must check browser compatibility to ensure all visitors can access their sites without errors. While cutting-edge browsers work seamlessly with new TLS versions, some older devices struggle to catch up.

For example, it took a surprisingly long time for Opera Mini, older Android browsers, and Samsung Internet to add support for TLS 1.2 and 1.3. Shockingly, the Internet Explorer browser is not any better.

So what should you do? Our recommendation is to adopt TLS 1.2 or higher for your website security. Then, maintain TLS 1.2 backwards compatibility to ensure accessibility across all browsers. Over time as usage declines, you can phase out support completely.

SSL and Web Hosting

When choosing a web hosting provider, one of the first things to look for is whether they implement robust security for your site. Reputable web hosting companies have migrated from outdated SSL to modern TLS protocols. However, most hosts still use the term “SSL” in their offerings, even when referring to TLS.

That’s mainly because of the omnipresence of the term “SSL”. It has become synonymous with online security. In other words, it’s a branding thing. Since most customers understand what is meant when hearing “SSL,” the entire industry still uses the term. But make no mistake, it does refer to TLS in most cases.

This confusion is also the reason why you must double-check that the hosting provider is actually offering TLS support, not just SSL. You can easily do this by looking at their security protocols and making sure that TLS is implemented.

When choosing a host, look beyond the names and ensure they offer the latest TLS versions. Here are some key considerations:

• TLS Certificate Options: Good hosts provide domain-validated (DV), organization-validated (OV), and extended validation (EV) TLS certificates from trusted CAs.
• Automatic TLS Certificate Installation/Renewal: Many hosts automatically install and renew TLS certificates for simplicity and continuity.
• Support for Modern TLS Versions: Only use hosts supporting TLS 1.2+ to avoid vulnerabilities in older TLS and SSL releases.
• Performance Optimization for TLS: Top hosts implement TLS speed boosters like HTTP/2 and SSL/TLS acceleration.

Conclusion

We hope this guide served as a helpful introduction to the differences between legacy SSL and modern TLS protocols. Here are some key takeaways:

• TLS evolved from SSL to offer better website encryption through improved security, speed, and capabilities.
• TLS 1.3 currently provides the fastest and most secure way to safeguard online communication.
• All modern web browsers and servers support TLS, while SSL has been deprecated and should be avoided.
• When choosing a web host, look for providers offering the latest TLS versions and optimization features.

At Softailed, we gather the top web hosting services based on various factors, one of which is security. Check out our Best Picks for Security to find the web hosting providers with the highest security standards.