SSL/TLS certificates: Their role in modern digital security

What is an SSL certificate?

An SSL certificate is a type of digital certificate that authenticates the identity of a website and establishes encrypted communications between two endpoints. This small data file leverage the TLS (Transport Layer Security) protocol, which is the successor to the SSL (Secure Sockets Layer) protocol. Commonly referred to as SSL/TLS certificates, they serve two functions:

1. Authentication: SSL certificates serve as credentials to authenticate the identity of a website. They are issued to a specific domain name and web server after a Certificate Authority, also known as a Certification Authority (CA), performs a vetting process on the organization requesting the certificate. Depending on the certificate type, it may include verified information about the business or organization behind the website.
2. Secure data communication: When an SSL certificate is installed on a web server, it enables a padlock or tune icon to appear in the web browser(depending on the browser). It activates the HTTPS protocol and creates a secure connection between the server and a browser. It enables use of encryption algorithms to scramble the data in transit into an indecipherable format that can only be read with the proper decryption key. This means sensitive data, like financial information, can be transmitted in a secure manner.

Web browsers show secure indicators when a site presents a certificate issued by a trusted Certificate Authority, like Sectigo. To become a trusted CA, a company must comply with and perform regular audits for the security and authentication process standards established by the leading browsers and the industry standards body called the CA/Browser Forum.

When a trusted CA issues a certificate to an organization, the browser will recognize the certificate as legitimate. The browser lets the user know that the web address is secure, and the user can safely browse the site and enter personal information.

How do SSL certificates work?

When a person visits a site with an SSL/TLS certificate, a "handshake" occurs to create a secure channel between the user and the organization and protect any data submitted on the website from being compromised. Here's how the handshake process works in real-time:

1. A client system such as a popular web browser connects to a server secured with an SSL/TLS certificate.
2. The browser initiates a TLS handshake with the server.
3. The server sends back a copy of its SSL certificate, including type, validity period, and organizational details.
4. The browser checks whether the certificate is valid. If the certificate is not installed, not up-to-date with the proper security protocols (has been allowed to expire), or not issued by a CA trusted by the browser, the user will see a warning message.
5. The server and browser complete key exchange and handshake messages, then begin a TLS encrypted session.
6. Any data shared between the browser and the server is now secure. If a hacker intercepts the communication, it will remain encrypted and unreadable.

Digital certificates are components of Public Key Infrastructure (PKI), which uses public key cryptography to establish trust. This process uses public and private keys to help establish encryption keys that protect data in transit.

What is the difference between SSL vs TLS?

TLS is an updated version of SSL that provides advanced encryption options, however the two acronyms are often referred to as having the same meaning.

Secure Sockets Layer, or SSL, was the name of the first cryptographic protocol established to ensure the identity of a server connected across the open internet. This protocol was created in 1995 to enable e-commerce on the web. SSL 2.0 was the first version of the protocol to be used in production systems, and it was soon superseded by SSL 3.0. After version 3.0, standards bodies superseded SSL with a more advanced protocol called Transport Layer Security, or TLS. However, by that point the term SSL was so common that it continues to persist as the de facto name for TLS.

Although certificates do not themselves perform encryption, standards-based client and server software require the presence of one for encryption to take place. This requirement is in recognition of the fact that without a reliable identity for the party on the other side of a connection, encryption itself offers no protection.

Common public key algorithms used in TLS today include RSA (Rivest-Shamir-Adleman) and ECC (Elliptic Curve Cryptography). However, as quantum computing advances, these algorithms are expected to become vulnerable, making a transition to post-quantum cryptography (PQC) necessary to maintain long-term security.

What are the different types of SSL certificates?

There are three different types of SSL/TLS certificates categorized by validation level, including:

• Domain Validation (DV): easiest and most cost-effective way to receive industry-standard encryption
• Organization Validation (OV): a step up from DV where an organization must be a legally registered business and prove they own the domain
• Extended Validation (EV): provide the highest level of trust and is the industry standard for e-commerce websites 

Other variations of certificates are categorized by the number of domains they cover:

• Wildcard SSL certificates: for a main domain and its subdomains
• Single Domain: for a main domain and a single subdomain
• Multi-Domain: used to secure multiple domains
   

Common uses

SSL certificates are an essential part of any website’s cybersecurity measures. Millions of websites use them to secure browsing on their websites. Enabling HTTPS helps signal that a site is protected for browsing and data entry, and leading browsers actively warn users when a site is not secure. Sites without a certificate may display a “Not Secure” warning.

The growth of global websites, mobile, and internet-connected devices has also expanded the use well beyond just e-commerce. Anyone who needs to share data between devices over the internet securely can benefit from SSL certificates. They are most commonly used to secure:

• Online credit card transactions
• Web forms and customer logins
• Email and webmail applications
• Corporate communications through intranets, file sharing, extranets, and internal servers
• Cloud-based platforms and virtualized applications
• File transfers over FTPS
• Data transfer to and from mobile devices

If a website URL starts with HTTPS:// and there is a padlock icon in the address bar, then the website is using a secure SSL/TLS connection.

What are the benefits of SSL certificates?

The primary importance of installing an SSL certificate is to initiate a secure session between a web server and a browser. Once a secure connection is established, all information passed between the web server and the visitor will be kept private and encrypted

Other advantages include:

• Increases customer trust: The padlock or tune icon assures customers that their information will not be compromised. The data will be sent to the intended target servers, and it will not be redirected to unauthorized third parties.
• Protects sensitive information against phishing attacks: Phishing sites are fraudulent copies of famous websites whose purpose is to trick you into submitting valuable information like your credit card or social security numbers. Extended validation certificates provide the highest level of identity validation, which can help users and organizations distinguish legitimate sites from impersonators.
• Better search engine rankings: SSL/TLS certificates can support SEO and a website’s online presence.  Google has confirmed HTTPS as a ranking signal, adding to its importance.

How to install an SSL certificate

There are 3 simple steps for installing an SSL certificate on a website:

1. Purchase a certificate issued by a trusted CA - Trusted certificates can be bought from your web-host or direct from a trusted CA, like Sectigo. SSL certificates from a trusted CA will be recognized by all popular internet browsers used by your visitors (Chrome, Firefox, Internet Explorer, Safari, etc).
2. Activate and install the certificate - If you bought your certificate from your web-host then they can do this step for you. If you are managing the site yourself then the two steps you need to complete are to generate a certificate signing request (CSR) and then to install your certificate. We have a range of documents to help complete both tasks on different web server software in our knowledge base.
3. Convert your whole site to HTTPS - After installing your certificate on your target pages, modify your site so that all content is served securely.

Certificate lifecycle management

Installing an SSL/TLS certificate is only the beginning. Certificates must be monitored and renewed before they expire to avoid issues like unplanned outages. 

This becomes significantly more demanding as the industry shifts to shorter public SSL certificate lifetimes, with the maximum validity moving to 200 days in 2026, 100 days in 2027, and 47 days in 2029. At this rate, automated certificate lifecycle management through a platform like Sectigo Certificate Manager (SCM) is the practical way to maintain coverage and reduce expiration risk.

Getting started

Sectigo offers every type of SSL/TLS certificate for purchase along with 24/7 support for customers. As a leading commercial public CA, Sectigo has issued more than 1 billion certificates worldwide.

If you need help understanding how SSL/TLS certificates work or selecting the right one for your website, contact us today.

Want to learn more? Get in touch to book a demo of Sectigo Certificate Manager!