SSL Certificate Trust Chain: Everything You Need to Know

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Understanding the chain of trust of SSL certificates can be a challenging task if you are not familiar with the concept of public key infrastructure.

You are dealing with a series of digital certificates, each of which confirms the authenticity of the previous one. It is a strict hierarchy designed to ensure the integrity and security of data transfer between networks.

The chain begins with your browser trusting the root certificate, moves through intermediate certificates, and culminates in the server's SSL certificate. Yet there's more to this cryptographic journey than meets the eye.

Let's unravel this complex process together!

Table of contents

What is an SSL certificate chain of trust?
Components of the SSL Certificate Trust Chain
How does the SSL certificate chain of trust work?
The Importance of the Certificate Trust Chain
Example of SSL certificate chain
Troubleshooting Chain of Trust Issues
What is an SSL certificate chain of trust?
An SSL certificate chain of trust is a sequence of certificates, each of which verifies the previous one. It is like a digital passport, ensuring that the data you send and receive is safe and comes from a trusted source. The chain of trust is a series of checks that the browser performs to ensure that certificates are genuine.

When you visit a website, your browser checks to see if the site's SSL certificate is valid . If it is, the browser will check the certificate's chain of trust. This involves checking the digital signature of each certificate in the chain, starting with the website's certificate and ending with the trusted root certificate. If all certificates in the chain are successfully verified, your browser will trust the site and establish a secure connection.

Components of the SSL Certificate Trust Chain
We're going to look at the components of the SSL certificate trust chain: the Root CA, the Intermediate CA, and the Server (leaf) SSL certificate .

Each of them plays a crucial role in establishing mobile app development service a secure, encrypted connection between the client and the server. Learning their functions will help you understand how trust and data security work on the Web.

Root Certification Authority
A root certificate authority is the cornerstone of the SSL certificate system, serving as the highest level of trust in online security. Its primary role is to issue root certificates that attest to the authenticity and security of websites.

By self-signing its certificate, the root CA establishes a basis of trust in the certificate hierarchy. These certificates are then used by intermediate CAs to issue certificates to individual websites, forming a chain of trust.




Browsers rely on a root CA to verify the legitimacy of websites by issuing trusted certificates. This process underpins secure online communication and transactions.

Therefore, you should be aware of the different levels of trust associated with different root CAs. Some are more widely recognized and accepted, resulting in more reliable validation of certificates.

Intermediate Certification Authority
Below the root CA in the chain of trust is an intermediate CA, which links the trusted root authority to certificates issued to websites. As the name suggests, an intermediate CA acts as an intermediary, issuing intermediate certificates to extend trust from the root authority to endpoint sites.

An intermediate CA decentralizes trust and improves security by preventing the Root CA from influencing it. It signs certificates using its private key , which can be verified using its public key contained in the intermediate certificate. This signature creates a chain of trust extending from the root authority to the server through the intermediate CA.

This hierarchy ensures that even if the private key of an intermediate CA is compromised, the security of the entire chain remains intact because the breach is at an intermediate level and does not affect the root certificates.