An SSL handshake is the process that kicks off a secure connection between a web browser and a web server. When someone visits a website that starts with "https://", this handshake automatically kicks in. Its main job? To make sure any information shared between the website and the visitor is scrambled up (encrypted) so no one else can read it.

It's like a secret digital handshake where the browser and server say hello, decide on a secret code for their conversation, and double-check each other's IDs – all before any sensitive details are sent back and forth.

This is important for keeping websites secure, especially if you're dealing with things like personal details, payment information, or login credentials.

How does the SSL handshake work?

The SSL handshake might sound technical, but it follows a straightforward series of steps in the background whenever someone loads your website over HTTPS.

1. Client hello
   The visitor's browser says "hello" to the website's server. It also shares some information like the different secure communication methods (SSL/TLS versions) and scrambling techniques (encryption algorithms) it understands.
2. Server hello
   The website's server responds with its chosen settings. This includes its digital security certificate (SSL certificate) and the specific scrambling method it wants to use.
3. Certificate validation
   The visitor's browser takes a close look at the server's SSL certificate to make sure it's legitimate and issued by a trusted organization (a Certificate Authority). If anything looks suspicious, the browser will usually warn the visitor.
4. Key exchange
   The browser and server work together to create a unique "session key." This key is like a secret code that they'll both use to scramble and unscramble all the information they exchange from this point on.
5. Finished message
   After they've both confirmed the secret key exchange worked, the browser and server send a final "all good" message to each other. Once this is done, their secure, encrypted conversation begins.

All of this happens in the blink of an eye, so visitors get a smooth browsing experience while their data stays protected.

Why SSL handshakes matter 

If you run a website, especially one where people share information or make payments, a successful SSL handshake is a big deal. It shows your visitors that your site is trustworthy and that their information will be kept private and safe from tampering.

It also affects SEO. Google gives ranking preference to secure (HTTPS) sites and warns users when they try to visit an insecure one.

A failed handshake can result in a browser error that prevents users from accessing your site—hurting trust and potentially your bottom line.

Common reasons an SSL handshake might fail

Sometimes things can go wrong with the SSL handshake. Here are a few common culprits.

• Expired SSL certificate
  If your site’s certificate isn’t valid, browsers will block the connection.
• Protocol mismatch
  If the client and server don’t share a common SSL/TLS version or cipher suite, they won’t be able to agree on how to communicate securely.
• Incorrect server configuration
  A misconfigured server might cause the handshake to break down during the key exchange.
• Firewall or network issues
  Sometimes security software or firewalls interfere with the handshake process.

How to check if your site’s SSL handshake is working

Here are a few ways to make sure everything is running smoothly.

• Visit your site in a browser. Make sure you see the padlock icon in the address bar.
• Use an SSL checker tool. Free tools like SSL Labs will run a full handshake simulation and report back any issues.
• Review browser console logs. Use Developer Tools in Chrome or Firefox to look for SSL errors in the Network tab.
• Set up automated certificate monitoring. Get notified before your certificate expires so you can renew it on time.

FAQs about SSL handshakes

What happens during an SSL handshake?

An SSL handshake establishes trust between the client and server. This involves exchanging digital certificates, agreeing on encryption methods, and creating unique session keys before any private data is transmitted.

Why would an SSL handshake fail?

Common reasons include outdated security certificates, a mismatch in communication methods between the browser and server, or incorrect server settings. Sometimes, network firewalls or older browsers can also cause issues.

How long does an SSL handshake take?

When everything is set up correctly, an SSL handshake happens very quickly – usually in less than a second. Most people browsing the web never even notice it happening.

Is an SSL handshake part of HTTPS?

Yes, absolutely. Every website that uses HTTPS (the secure version of standard web communication) starts with an SSL (or the newer TLS) handshake. This is what ensures the connection is encrypted and that the website's identity has been verified before any data is exchanged.

Build a secure website with B12

B12 makes it easy to launch a secure, professional website that includes automatic TLS certificates. No setup required – just publish and go. Launch your secure site today!