A quick explanation of Root CA certificates – Comodo RSA domain validation secure server CA

In this article, we’ll explain what a Comodo RSA Certification Authority is and why it’s the most respected authority for signing SSL certificates.

Comodo RSA Certification Authority

Comodo RSA Certification Authority refers to the Comodo CA’s root. Essentially, this is the root from which all other SSL certificates are signed and they are consequently chained to it. Comodo RSA is currently the world’s most trustworthy certification authority with over 100 million websites secured. You can explore more about Comodo CA through our exclusive blog post “Comodo SSL Review – Why It’s a Top-Notch Certificate Authority.”

Comodo RSA: Glossary of Terms

It’s possible that you’re confused about some of the terms we’ve used in the explanation above. For the non-initiated, the following is a comprehensive glossary of SSL-related terms.

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Root Certificate

The Root Certificate, or the issuing SSL certificate, is generally preinstalled into a web browser’s trust store. As such, the user’s browser needs to climb up the chain of trust and it needs to be linked to the trusted root. Only then can the SSL certificate be trusted. The SSL certificate can be chained directly to the root. However, it usually links through a series of intermediate certificates so the issuing root is not compromised. Read our previous blog post for Comodo Root Signing Certificate and Comodo Intermediate Certificate.

Certificate Chain

As mentioned above, the SSL certificate links through a series of intermediate chains — not directly — to the root certificate. If the SSL certificate doesn’t link back to a root, the browser will not accept it. The chain that is formed to link back to the root is called a Certificate Chain.

Intermediate Certificate

It is technically possible for an SSL certificate to link directly to the root certificate. However, trusted roots like Comodo RSA Certification Authority are extremely valuable. As such, certificate authorities don’t issue directly from them so that they are not exposed and there’s no chance of them being compromised. To protect the root, CAs issue the certificate through intermediate certificates.

Intermediate certificates can be used for two purposes:

  • The Certification Authority may issue directly from the intermediary.
  • The intermediate certificate can be sold to another Certificate Authority lacking a trusted root. This is referred to as cross-signing.

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