A Secure Sockets Layer (SSL) or Transport Layer Security (TLS) handshake is a digital greeting between a user’s browser and a website’s server. It (SSL/TLS handshake) creates a secure connection between a client and a server by encrypting data.

Today’s businesses focus on keeping their users safe, increasing the demand for SSL/TLS certificates. They (SSL/TLS certificate) protect visitors and website owners from online threats, creating a safer browsing experience for everyone.   

In this article, we’ll dive into behind-the-scenes of SSL/TLS certificates and understand how SSL/TLS handshakes work. 

What is an SSL/TLS Handshake?

The SSL/TLS handshake is a process that allows the client and server to establish secure communication. This handshake acts like a negotiation between two parties over a network, setting up the rules for secure data exchange. An SSL/TLS handshake generally has four main phases. Here’s a peek into the four phases of an SSL/TLS handshake: 

  • Deciding the protocol version  
  • Certificate and key information  
  • Verifying server information  
  • Final security checks and cipher agreement 

Once this handshake is finished, the client and server can securely share information and communicate using the agreed security settings.  

ALSO READ : What Is the Difference Between SSL and HTTPS  

How Does the SSL/TLS Handshake Work?

Here’s a step-by-step guide on what happens during an SSL/TLS handshake:  

Step 1: ClientHello Message:

SSL/TLS handshake starts when the client (typically your browser) sends a “ClientHello” message to the server. This message contains key details like the SSL/TLS version it supports, a list of cipher suites (encryption options) it can use, and a random string known as the “client random.” 

Step 2: ServerHello Message

The server responds to the client’s message with a “ServerHello” message, which includes its own chosen cipher suite (selected from the client’s list), its public key, a digital certificate, a session identifier, and a random string called the “server random.” 

Step 3: Certificate Verification

Next, the client authenticates the server by checking its digital certificate with a Certificate Authority (CA). This step verifies the server’s identity and ensures the client is connected to a trusted and legitimate source. 

Step 4: ClientKeyExchange Message

After the client verifies the server’s certificate, it uses the server’s public key to generate a unique, random value called the premaster secret. It is a random value generated by the client during the SSL/TLS handshake; its main purpose is to securely establish the shared secret key between the client and the server.  

The client encrypts this premaster secret using the server’s public key and sends it to the server. Only the server, which holds the matching private key, can decrypt it. 

Step 5: Server Decrypts Premaster Secret

The server decrypts the premaster secret using its private key, gaining access to this important piece of data that will help both sides create a shared secret key. 

Step 6: Creating a Shared Secret Key

With the premaster secret in hand, both the client and the server use it, along with their client and server random values, to generate a shared secret key. This key is what they’ll use to encrypt and decrypt the data exchanged from this point forward. 

Step 7: Client Sends a “Finished” Message

The client now sends an encrypted “finished” message using the shared secret key. This message signifies that the client’s side of the handshake is complete. 

Step 8: Server Sends Its “Finished” Message

In response, the server sends an encrypted “finished” message back to the client, confirming that the server has also completed its part of the handshake. 

Step 9: Secure Communication Begins

With the handshake complete, the client and server can now exchange data securely. They use the shared session keys created during the handshake to keep the communication private and protected. 

In some cases, the client also verifies the server, which adds an extra layer of security. This mutual authentication ensures that both the client and the server are who they say they are, strengthening trust on both sides. 

ALSO READ : SSH vs. SSL: What’s the Difference? 

What is the Difference Between SSL and TLS Protocol?

SSL is a network protocol that creates a secure link between two devices or applications over a network. Its main job is to authenticate the other party before any sensitive data is shared.  

SSL has been the most popular encryption method for the past few decades. However, due to some security flaws, SSL has now been replaced with TLS.  

TLS is the improved and more secure version of SSL. It was developed to fix SSL’s weaknesses, making encrypted communication even safer. TLS is better at authenticating users and devices and provides a more reliable way to keep data protected as it moves between a client (like your browser) and a server. 

So, while both SSL and TLS are used to secure online interactions, TLS is the current standard because of its enhanced security and efficiency. 

Summing Up

The SSL handshake is a key process that quietly and quickly secures online communication. Most people don’t even realize it’s happening in the background; without it, user data and server resources would be vulnerable to attacks. 

However, for a secure SSL/TLS handshake, both the client and server need to agree on compatible cipher suites and SSL/TLS versions, which are essential to kickstarting the secure connection.  

If you are looking for a safer and more secure way to keep your online data safe, opt for reliable SSL certificates, like those from BigRock. Our SSL certificates offer robust encryption and protection, keeping data safe from prying eyes and providing a trustworthy shield against online threats.  

Frequently Asked Questions (FAQs) on SSL/TLS Handshake

1. What is SSL/TLS used for? -H3 

SSL/TLS are network protocols used by HTTPS and other network protocols for encryption. 

2. Which is better, TLS or SSL?

SSL and TLS both serve the same purpose. However, TLS is an updated version of SSL that can handle encryption without any security vulnerabilities.  

3. What is the TLS protocol?

TLS is a network protocol that provides end-to-end security for data sent on the Internet. Users remember TLS protocol through the padlock icon that appears in web browsers when a secure session is established.   

4. What is the difference between HTTPS, SSL, and TLS?

SSL and TLS are network protocols that are used to encrypt data during online transmission. HTTPS is an extension of the Hypertext Transfer Protocol (HTTP) that’s used to send data between a web browser and a website.  

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