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What Is an SSL Certificate and How Does it Work?

An SSL/TLS Certificate enables a website to possess a strong level of security through encryption. Thus, building trust from a potential customer base. Various types of SSL certificates exist on the internet, which comes into place when choosing the right one for your website. In this article, we will try to shed light on the definition of SSL/TLS, a brief history and different categories of certificates.

What Is An SSL certificate

So,  what is an SSL certificate? An SLL (Secure Socket Layer) enables the possibility for a secure link from a website to a visitor’s web browser. This ensures that information & data between the two parties remain encrypted. SSL encryption blocks hackers and cyber-thieves from obtaining personal information; credit card details, addresses, identification, etc. 


A Brief History

In 1995, SSL was developed by Netscape. The first released version was entitled SSL 2.0, the original version (SSL 1.0) was not released - according to SSL history. One year later, SSL 3.0 succeeded version 2.0, followed by the detection of various weaknesses in the second edition. Keep in mind version 2.0 and 3.0 can also be written as SSLv2 and SSLv3.

1999 was the year when TLS was released, succeeding SSL. It was written on the same grounds as SSL 3.0:


Remember: Certificates & protocols differ from each other.


How Does SSL (Digital Certificate) Work

A common question among many internet users is “how does SSL work?” Basically, the moment a web surfer stops by secure web pages are faced with an SSL certificate. Within the space of a split second, an encrypted connection is accomplished by obtaining information regarding the server.


  • If a website possesses an SSL/TLS certificate, the browser usually detects it. As a result, the browser and the SSL certified website perform what is known as the SSL handshake.

  • The SSL handshake is when a browser scans and detects for the SSL certificate, to ensure the web page is correctly authenticated.

  • SSL certificates possess something known as an associated public key and private key. Each key differentiates between encryption and decryption, and determines the necessary protocols which should be applied. This is done when the SSL handshake takes place - in order for secure communication.

  • Once the visitor shows the validation of the certificate, a “session key” is created by the browser and the domain’s server. Known as a  “symmetric” key, it is necessary for the rest of the secure connection. Meaning efficiency is at its peak when it comes to encryption which results in a high-speed communication process through SSL.

  • The final part of the handshake lasts about 300 milliseconds. As a result,  a secure connection is ongoing, and the two parties have the ability to communicate without the risk of thieves or hackers. It doesn’t matter which side of the globe they are on.


What Is The Purpose Of An SSL certificate

A company or individual who owns a website,  is required to install an SSL Certificate to their web server. So, what is the purpose of an SSL certificate? The purpose of an SSL certificate is to create the possibility for secure sessions between the server and the web browser. When a secure connection is created, web traffic among the web server & browser becomes secure. 


After a certificate has been installed onto a server, the URL of the domain will change. Rather than “HTTP”, it is “HTTPS” - ‘S’ meaning secure. When visitors enter a domain which possesses an SSL certificate, their browsers display either a padlock or a green bar. Depending on the type of certificate a developer has used, and the browser a visitor is using.


See below for examples.

  • Provide secure communication between the website & browser.
  • Provide secure communications within a company’s intranet.
  • Securing information & data among both internal and external servers.
  • Encrypting and decrypting information sent and received using devices.
  • Develop a loyal customer base.
  • Increase conversion rates.


To provide a secure web-surf, Google detects and points out domains which do not possess an SSL/TLS Certificate from its search results. Usually, the URL bar would have a warning sign stating “not secure” on both Google Chrome and Mozilla Firefox. It’s safe to speculate about the possibility that these browsers may block websites without certificates in the future. 


If anyone fails to comply with this rule, all the popular web browsers used around the globe like Google Chrome & Firefox Mozilla will punish them by giving a warning message of ‘Not Secure’ on the URL bar. It could be possible that in the near future website may even get blocked to load on the browser.


Different Types of Certificates 

It’s safe to say that without an SSL Certificate, catastrophes may occur. The good news is that there are various types of SSL Certificates offered. 


Certificates can be categorized by:

  1. The number of secured domains/subdomains;
  2. The validation level.


Types of Certificates By Number of Domains

There are various different types of SSL Certificates. From a technical perspective, each type can be categorized depending on the domains they were built for.



SAN/Multi-domain SSL

When an individual desire to use multiple domain names securely, while using the same SSL certificate, then SAN/Multi-domain allows that to happen. The original domain acts as the base domain. For example. The other domains act as SAN (Subject Alternative Name). For example,, and so on. 


SAN/Multi-domain SSL Certificate is offered through all of these three SSL certificate options. A Single Multi-domain SSL Certificate is able to guard around 100 domain names. 






Wildcard SSL

Wildcard SSL is appropriate for developers who have the desire to secure a domain name, which has multiple-subdomains on the same certificate. This form of certificates has the ability to secure a base domain, along with any amount of first-level domains. Wildcard SSL Certificate is offered with domain validation (DV) and organization validation (OV).





Unified Communication Certificates (UCC)

Unified Communication Certificates were created for the sole purpose of securing Microsoft Exchange Server & Microsoft Office Communication Server. The UCC acts in the same way as a Multi-Domain SSL Certificate (mentioned earlier in this article). Thus, it has the ability to maintain the security of a base domain, followed by various fully qualified domain names (up to 25 to 100). The figure of sub-domains secured is dependent on the Certificate Authority (CA).





Multi-Domain Wildcard SSL Certificate

Multi-Domain Wildcard SSL Certificates enable developers to maintain the security of multiple domain names. This is followed by an unlimited number of sub-domains. It is offered with domain validation (VC) and organization validation (OV).



Types of Certificates By Validation Level

SSL/TLS certificates are offered in various ways in the perspective of identity validation. To put things into understandable words, a high amount of identity validation equals to a more dependable certificate. However, identity validation takes time to obtain to a high level. 


Extended Validation (EV)

Browsers display a green address bar with EV certificates, this indicates risk-free communication through top-level security. The green bar is universally recognized as trustworthy on web browsers. It’s a good idea for eCommerce websites, which require the trust and loyalty of visitors, to purchase an EV certificate.


Organization Validation (OV)

OV Certificates differ from EV Validation because the green bar is not included. However, OV does activate the trust indicators on a web browser. The requirement for a company that wishes to obtain an OV  is to possess a verification from the Certificate Authority.

On the SSL Certificate Validation, the name of the company or institution is included. Meaning, the website looks more trustworthy and secure. The use of OVs among both private and public organizations is high, as they show that a platform is more trustworthy to users. OV certificates are vital for companies who were unable to obtain an EV certificate, regardless of the reason. 

Domain Validation (DV)

DV Certificates deliver industry-standard encryption on the volume of other certificate categories. Meaning, it doesn’t offer an ample amount of additional features in comparison to the rest. With it’s low-cost or free of charge aside, the benefit of the DV Certificate is the fast waiting time. This is because there is an automated process in which the Certificate Authority is only required to validate your domain name.


How to Find Information About SSL Certificate

Now we know about SSL/TLS Certificates and their types. Which brings us to a few questions: How do we find SSL Certificates? How can we find information regarding SSL Certificates?

There are various methods of SSL certificate data exploration. Though, the fastest and most convenient way is to make use of the Spyse search engine. This helpful service collects large amounts of valuable data regarding SSL Certificates; the expiration date, certificate serial number, type of certificate and other valuable information.