What Is A Chain Of Trust And How Does It Work In 2021

chain of trust internet and how it all works

A public key infrastructure offers several security-related services. These Services are based on the proper use of public and private keys. The public component of this key pair is associated with the Public-Key Certificates.

A public-key certificate is an important node of the certificate chain. It has signed a statement that is used to establish a relation between identity and public key. This is what we know as Machine Identity.

In order to associate identity and the public key, a chain of certificates is used. This certification chain is also known as the certification path of the chain of trust. This article will explore more about this chain of trust and see what it is and how it works.

What Is A Chain Of Trust?

A chain of trust or a certificate chain is a list of certificates followed by one or more CA certificates. They basically refer to the SSL certificate and how it is linked back to the other certificate authority.

In order for the SSL security to be trusted by the other, it needs to have a traceable path back to its trust root. We know this explanation is raising more questions than answering. Perhaps the following properties will help you better understand what a chain of trust is.

  • The issuer of the certificates matches the subject with the other subject.
  • Each certificate must be signed by a secret key corresponding to the next certificate in the line.
  • The last certificate in the list is the trust anchor and holds your trust because it was delivered to you from a public authorized certificate authority.

In layman’s terms, the chain of trust refers to the SSL/TLS certificate and how it is linked back to the authorized certificate authority.

What Is A Chain Of Trust And How Does It Work In 2021

3 Basic Entities Of Chain Of Trust

The chain of trust is divided into three basic entities that define the different features of the chain of trust. Let’s have a look at the entities and see what each has in store for us.

1. The Trust Anchor – Root Certificate

A root certificate is a self-signed certificate.  It follows the standard of the X.509 certificate. The root certificate plays an anchor role in the whole chain of trust. If the trust anchor’s private key is compromised, all the certificates issued by the CA will be affected.

This will end up with reissuing all the certificates at the intermediate level. Hence, for the root certificate, it is necessary to keep track of the public keys and private keys all the time.

2. The Issuing CA – Intermediate Certificate

No matter what activity is happening, there is always a single intermediate certificate in the SSL certificate chain of trust. They offer vital links to connect the root CA and extend its trustworthy reputation.

The issuing CA acts as a middleman and connects the root certificate and server certificate. This allows the root certificate to be securely stored offline.

3. The End Entity – Server Certificate

It is the server certificate’s responsibility to offer compliance, security, and scalability with CA standards. However, the certificate itself does not guarantee whether the subject is trustworthy or reputable in the business. 

Server certificate users are not always part of the certificate. The use case of the certificates depends on the environmental requirements.

How Does The Chain Of Trust Work?

When you receive the SSL certificate, you will immediately be sent with a root certificate. When the browser downloads your SSL certificate package when it arrives for the first time on your home page, it begins chaining the certificates back to the root certificate.

If the certificate is valid and can be chained back to the root certificate, your SSL certificate will be trusted. 


The certification chain of trust is also known as the certificate path. It is a list of certificates used to verify identity—the Process of identifying begins with a certificate of the entity and is signed with encryption corresponding to the next certificate in the line.

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