How Does SSL Work?

November 21, 2023 / Security and Privacy


With cyber threats constantly evolving and sensitive data exchanged across the internet every second, the need for online security has never been more critical. This is where SSL (Secure Sockets Layer) steps in to protect your online transactions and communications. In this post, we will explain what SSL is, what it is used for, and, most importantly, how it works to keep your online business secure.

What is SSL?

SSL is a cryptographic protocol that ensures secure communication between a user’s web browser and a web server. It establishes an encrypted connection, safeguarding the integrity, confidentiality and authenticity of data transmitted between these two endpoints.

What is SSL used for?

SSL serves a number of important purposes:

Data encryption

SSL encrypts data transmitted between a browser and a web server, making it indecipherable to any malicious actors attempting to intercept it. This encryption ensures that sensitive information, such as login credentials, credit card details and personal messages, remains confidential.

Data integrity

SSL guarantees the integrity of data by detecting any unauthorised alterations during transmission. If any changes occur in the data during transit, SSL will alert both the sender and receiver, preventing the acceptance of tampered data.


SSL also validates the authenticity of your website. When users visit your site, their browser checks the SSL certificate presented by the server to ensure that it has been issued by a trusted Certificate Authority (CA). This process assures them that they are communicating with a legitimate website and not a fraudulent one.

Domain Name


Websites with SSL certificates display a padlock symbol in the address bar and use the ‘https://’ prefix in their URLs. These visual indicators build trust among users, assuring them that their interactions with the website are secure. This trust is crucial for online businesses, as it can lead to increased customer confidence and, consequently, higher conversions.

How Does SSL Work?

SSL employs a combination of cryptographic techniques to secure the data exchange between your browser and the web server. Here’s a step-by-step breakdown of how SSL works:

  1. Initiation: The SSL handshake process begins when users connect to a website secured with SSL (HTTPS). Their browser sends a ‘Hello’ message to your web server, indicating its intent to establish an encrypted connection.
  2. Server authentication: In response to their ‘Hello’ message, your web server presents its SSL certificate, which contains its public key, issued by a trusted Certificate Authority (CA). The user’s browser then checks the certificate’s validity and verifies that it trusts the CA that issued it.
  3. Key exchange: Once the user’s browser is satisfied with your server’s certificate, it generates a random symmetric encryption key known as the ‘session key.’ This session key will be used exclusively for this session and ensures that the data remains confidential.
  4. Data encryption: The user’s browser encrypts the session key using your server’s public key, ensuring that only the server possessing the corresponding private key can decrypt it. This encrypted session key is then sent to the server.
  5. Secure communication: With the session key in hand, both the browser and the web server can encrypt and decrypt data using symmetric encryption. This ensures that all data exchanged between you and your user during the session remains confidential and secure.
  6. Data transfer: From this point onwards, all data, including web pages, images and user input, is transmitted securely using the session key. This encryption prevents eavesdroppers from intercepting and deciphering the data.
  7. Data integrity: As data is transferred, the SSL also calculates a message digest or hash for each transmitted piece of information. The receiving end verifies the hash against the transmitted data, ensuring data integrity. If any tampering is detected, the connection is terminated to protect the data.

Who needs SSL?

SSL is an essential security feature for anyone who operates a website, regardless of its size or purpose. E-commerce websites that handle financial transactions must have SSL to protect customers’ payment information while businesses of all sizes benefit from SSL to secure sensitive data like customer information, employee login credentials and internal communications. Additionally, search engines prioritise secure websites in their rankings, making SSL essential for better visibility in search results.

For more in-depth information on the importance of SSL certificates, especially for eCommerce websites, read: Why SSL Certificates are Vital for eCommerce Security


With so much personal and financial information sent over the internet today, SSL is vital in order to prevent that data from being accessed, stolen or tampered with during transit. Website owners have a duty to protect their users’ data and SSL is essential in putting that protection in place. With free SSL certificates, like Let’s Encrypt, now available, there is no excuse not to have one. However, for businesses and organisations that need greater levels of security, validation and warranty, premium SSL certificates are the best option.

For more information, see our range of premium SSL Certificates.


  • Arjun Shinde

    I'm an experienced digital marketer with expertise in planning, SEO, SEM, and social media. I'm good at creating engaging content and optimising campaigns for a strong online presence.

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