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Certificate Authority: What is it, and what do they do?

Certificate Authority (CA) is a trusted organization that validates and verifies the identities of entities, such as websites, email addresses, companies, or individual persons.

When you visit a website, you observe HTTPS before the domain name. An extra is due to a digital certificate, which is issued by the certificate authority.

An entity that works behind organization validation during issuance, certificate issuance, and renewal reissues everything that is required to secure your website. In this brief article, we will cover many parts of a certificate authority (CA). So, let us get started.

What is a Certificate authority (CA)?

A Certificate Authority (CA) is an organization or entity that validates a company’s identity who applies to get an SSL certificate. The certificate authority checks credentials like domain name, individual or company identity proof, and email address to issue an SSL certificate.

The certificate issued by the CA is bound by cryptographic keys to prevent data eavesdropping activities.

All SSL certificates issued are compatible with major browsers (Chrome, Mozilla Firefox, Opera, and Safari). A verified SSL certificate ensures end users about the website’s authenticity.

DigiCert, Sectigo, AlphaSSL, GlobalSign, RapidSSL and Comodo are a few well-known CAs in the industry.

In January 2024, top CAs whose certificates are used on top Alexa websites are IdenTrust, Sectigo, GlobalSign, DigiCert, Let’s Encrypt and GoDaddy.

Rank Certificate Authority Usage Market Share
1 IdenTrust 51% 55.30%
2 Sectigo (Comodo Cybersecurity) 11.01% 12%
3 GlobalSign 9.5% 10.30%
4 Let’s Encrypt 8.50% 9.20%
5 DigiCert Group 7.50% 8.20%
6 GoDaddy Group 4.50% 4.80%

Key roles of a certificate authority

Suppose you have wondered that how an extra ‘S’ is added to HTTP. Yes, this comes with an SSL certificate, which the CA issues after thorough verification.

In the absence of an SSL certificate, the browser throws an insecure warning, which can damage the reputation of a website.

The certificate authority binds the certificate with private and public keys and pre-decided industry standards for validation. Such measures are set by the CA/Browser forum (A forum of leading browsers and CAS).

When you install an SSL certificate on the server, it enables HTTPS before the domain name to ensure visitors that the website is safe to protect sensitive data.

The certificate authority’s market size is expected to rise from $180.18 million to $325.26 by 2029.

Certificate Authority Market

How Does Certificate Authority Work?

The certificate authority, in order to issue a certificate, issues a digital certificate, creates trust between the server and the browser, validates the domain name and organization’s identity, and maintains a certificate revocation list.

Certificate authority works on the Public key Infrastructure (PKI) system. To work with PKI in synchronization, there are certain phases that the CA has to follow to issue a certificate, which are as follows.

How Does Certificate Authority Work

  • Digital Certificate: A Digital or SSL certificate proves the website’s identity.
  • Public Key: A public key is used to encrypt the data.
  • Private Key: A private key is used to decrypt the data.
  • Certificate Authority: The certificate authority confirms the website’s identity and issues a certificate.
  • Digital Signature: A digital signature affirms that the certificate authority has issued an SSL certificate.

Why do we need certificate authorities?

A certificate authority is the backbone of a secure socket layer certificate. Without the CA, the website remains vulnerable, and a browser shows a warning.

When a customer tries to connect to a website, how will customers know that they are trying to validate a domain name? To ensure end users that the website they are approaching a proper website, certificate authorities issue an SSL certificate. An SSL certificate is a symbol of security that is taken care of by the certificate authorities.

List of Trusted Certificate Authorities

There are many trusted certificate authorities, including DigiCert, Comodo, Sectigo, GlobalSign, AlphaSSL, Thawte, RapidSSL, and GeoTrust.

These CAS offer reliable and authenticated SSL certificates to secure online transactions between the server and the browser.

How does a certificate authority issue a digital certificate?

The certificate authority uses the PKI system to issue a digital certificate. The certificate authority issues the certificate with an expiration date, after which the certificate authority no longer guarantees the certificate.

You should send a request to the CA to get a digital certificate. This certificate request should include your domain name, public key and digital signature. A domain name is a unique identifier for each user. The certificate authority checks the received public key and starts the validation process. The CA confirms the applicant’s identity by performing a validation process.

The validation process includes checking business registration documents, any legal entity registered documents, phone calls, etc.

After confirmation, the certificate authority sends a signed SSL certificate/digital certificate. The certificate includes the distinguished name of the CA, CA signature, public key and other essential information.

What is the difference between Root certificates and intermediate certificates?

Root Certificates Intermediate

  • Root certificates have multiple roots, which means browsers have their roots in trust stores.
  • Intermediate certificates do not have their root stored in browsers. Intermediate certificates link back to the third-party trusted root CA.
  • Root certificates issue certificates to intermediate CA instead of issuing a certificate to the end user. The root certificate remains offline.
  • Intermediate certificates are used to sign the end-user certificate. Root CAS issues Intermediate certificates under hierarchy. Intermediate certificates work like a trust chain between the root CA and the end-user certificate.

What is the CA/Browser Forum?

CA/Browser Forum was founded in 2005, and it is a volunteer group of different certificate authorities, browser vendors, software and other application vendors.

These vendors use X.509 certificates that use TLS/SSL protocol. The CA/Browser forum has decided on some policies and standards to issue a digital certificate, which is called Baseline Requirements.

Every certificate authority should follow these policies and standards. The main motto of such standards is to provide a secure online experience to end users as well as secure user communication.

When does the CA Certificate Get Revoked?

SSL certificate comes with a pre-defined expiry date. However, it can be revoked due to many reasons. The process is called PKI certificate revocation.

  • Suppose a CA finds that, the issued certificate is improper. The CA can reissue a new certificate and revoke the old certificate.
  • In case the certificate is counterfeit, the CA can revoke it. Such a certificate is stored in the certificate revocation list (CRL).
  • In case of a private key compromised, the CA can revoke the certificate.
  • If the CA itself is compromised, a certificate can be revoked.
  • If the site owner does not carry a valid domain name or closes his business, a certificate can be revoked.
  • The site owner has replaced a new certificate from a new SSL provider.

Public CA vs. Private CA Comparison

Browsers and computers trust public certificate authorities and their certificates. Both public and private certificate have their usage.

A public certificate avoids browser warnings and it is used to secure client-server or server-client communication.

In public CA certificates, browsers have their root certificates to trust the hierarchy of chain certificates.

Private CA certificates are added by the IT admin of an organization or by a trusted CA. It is used to protect the internal network.

Such certificates can secure server-to-server communication for non-registered domains.

Private CA certificates do not have their trusted chain certificate hierarchy embedded in browsers. CAs manage their policies to provide flexibility to the internal IT environment.

How to choose a certificate authority

Certificate authority should be carefully selected when you deal with an SSL certificate. There are certain things, which you need to consider like-

Advanced Technology

Your selected CA should offer advance cryptography and adhere to the latest development in SSL industry.

An old technology can hamper user experience on the website as browsers only considers the latest encryption standards. A modern cryptography and key sizes keep your data safe and avoids eavesdropping.

Customer Service

Customer service is an essential part of the selection of a CA. There are many stages when you need 24/7/365 customer service support for SSL related queries.

It may be validation related or deployment process, your customer support should be with you whenever you require it.

Helpful Tools

Different tools make certificate management easy. These tools easily manage and track certificates and manage and comply with policies. APIs are one of the best tools that can organize certificate management with automation

Best Price

The certificate authority should have a fair price compared to other providers. Many CAS charge a lot of money for a single SSL certificate, while others offer it at minimal costs.

You need an SSL certificate at the lowest price in terms of better service, easy-to-use interface and brand.


Always look for reviews, feedback, and ratings before you choose certificate authority. A well-reputed CA can help you grow in your business goal. Reliability and trustworthiness add extra value to the certificate authority.

Where to buy SSL Certificate?

It is the most confusing question that every website owner carries until he finds a suitable platform for website security, especially for an SSL certificate.

We here are ready to help you discover your SSL security at a nominal price. Yes, SSL2BUY brings a mesmerizing experience for your website security that includes essential steps starting from product selection to SSL installation.

So, end your search at SSL2BUY and leave all your worries to us. Just browse our SSL Certificate pricing page and buy an SSL certificate today at the lowest price that you hardly find anywhere.

Open Account, Product selection, configuration, validation and issuance of a certificate are the main parts that SSL2BUY follows for SSL certificate issuance.


The certificate authority plays a vital role in issuing an SSL certificate on which the whole site’s security is dependent. The increasing threat environment around us has compelled us to think about website security and customers’ data safety. Due to changes in cryptography standards and the ever-changing threat environment, the role of certificate authority will be challenging in the near future.

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About the Author

Apurva Barve

Apurva holds a master’s in Computer Science and has spent over 6 years immersing in SaaS Customer Services with a focus on SSL technologies. With a natural ability to understand customer needs, she has thrived in highly competitive markets, showcasing her adaptability and prowess in the ever-evolving SSL industry. When not decoding tech jargon, you'll find her sipping on coffee and enjoying the digital landscape.