





If you are a website owner, you obviously know what installing an SSL certificate on your website means. Not just securing trust and data, it also plays a key role in boosting your website’s ranking in Google. However, you might not know that your certificate doesn’t function inside a bubble. The SSL certificate chain includes it as a part.
If you want to truly understand what an SSL certificate chain is, you, at the very least, should have a basic idea about public key infrastructure (PKI), as PKI is a trust model that fortifies SSL certificates.
Public Key Infrastructure (PKI) facilitates the creation, management, distribution, usage, storage, and revocation of digital certificates through a system of digital certificates, certificate authorities (CAs), and other related hardware and software. PKI enables the use of digital certificates and public key encryption to secure electronic communications and transactions.
Got a basic understanding of PKI Certificate? Let us discuss what an SSL certificate chain is.
A certificate chain, also referred to as certificate hierarchy or SSL chain of trust, establishes trust between a client (such as a web browser) and a server (such as a website) by using a series of SSL certificates. The purpose of the SSL certificate chain is to establish a chain of trust between the client and the server.
When a client establishes a secure connection to a server, it checks the SSL certificate chain to verify the authenticity of the SSL certificate and to ensure that a trusted CA has issued the certificate. If the certificate chain is not valid, the client will not trust the certificate and will not establish a secure connection to the server.
Now that we know how the SSL certificate chain plays a key role in establishing confidentiality between the server and client let us check how it does so.
The SSL certificate chain is an important part of the SSL/TLS ecosystem and plays a critical role in establishing trust between clients and servers.
Before discussing how it works, let us discuss the three components involved in the process.
The certificate authority (CA) issues a self-signed root certificate. This root certificate signs one or more intermediate certificates.
The intermediate certificates sign the end-entity SSL certificate installed on the server.
When a client (such as a web browser) establishes a secure connection to a server, it checks the SSL certificate chain to verify the authenticity of the SSL certificate and to ensure that a trusted CA has issued the certificate.
The client checks the root certificate to determine if it trusts it. If the root certificate is trusted, the client trusts all the intermediate and end-entity SSL certificates.
The client establishes a secure connection to the server and begins exchanging encrypted data with the server.
If the client does not trust or find any of the certificates in the chain valid, the SSL certificate chain will be deemed untrustworthy. Consequently, the client will not establish a secure connection to the server.
Now that we know how the certificate chain works, let us get into its verification process.
The chain of the trust verification process is the process by which a client (such as a web browser) verifies the authenticity of an SSL certificate and establishes trust with the server. Here’s how the process works:
The client establishes a connection to the server and requests the SSL certificate.
The server responds with the SSL certificate and the certificate chain.
The client checks the trust store on its device to determine if it trusts the root certificate in the chain. If the client trusts the root certificate, it trusts all the intermediate and end-entity SSL certificates.
The client checks the SSL certificate’s expiration date to ensure it is still valid.
The client checks the domain name in the SSL certificate to ensure that it matches the server’s domain name.
If the certificate chain is valid and trusted, the client establishes a secure connection to the server and begins exchanging encrypted data with the server.
If the client does not trust or validate any of the certificates in the chain, it will consider the SSL certificate chain untrustworthy, and it will not establish a secure connection to the server.
In all of these examples, the certificate chain establishes trust between the client and the server and verifies the SSL certificate’s authenticity. The specific requirements of the certificate authority and the SSL certificate being used determine the number of certificates in the chain and the specific trust relationships between them.
Yes, incorrect configuration can sometimes cause errors in your SSL certificate chain. Let us talk about that.
When setting up an SSL certificate on your website, it is important to remember that you need to install not just the site’s certificate but also one or more intermediate (or chain) certificates. If the chain is wrong, it can cause browser certificate errors, which might make visitors leave your site. The chain could appear differently in different browsers as some cache intermediate certificates and download missing ones on-demand. When renewing your certificate, you might have to install new intermediates. You can visit our SSL tools, where you can check the SSL certificate chain online.
Run the below OpenSSL Commands to validate a certificate and its chain:
To verify a certificate and its chain for a given website, run the following command:
openssl verify -CAfile chain.pem www.yoursite.com.pem
To validate the intermediates and root certificate separately, use the -untrusted flag.
Note: -untrusted command used once for a certificate chain bundle of intermediates, or once for each intermediate in a separate file.
openssl verify -CAfile root.pem -untrusted intermediate.pem www.yoursite.com.pem
Add -show_chain flag to show the output the certificate chain and the relevant depth of each certificate in the chain.
openssl verify -show_chain -CAfile chain.pem www.yoursite.com.pem
A few common issues can arise with the SSL certificate chain and cause trust issues between clients and servers. Here are a few possible issues and steps you can take to troubleshoot them:
To troubleshoot this issue, check the expiration dates of all certificates in the chain and ensure they are all still valid.
Fox Fixing this issue, check the trust store on the client to ensure that the root certificate is trusted.
To troubleshoot this issue, check the order of the certificates in the chain and make sure they are presented correctly.
Obtain a trusted SSL certificate from a certificate authority to troubleshoot this issue.
These are some of the issues and their troubleshooting ways.
An SSL certificate ensures the security and integrity of your website via the application of secure HTTPS protocol. The chain of trust is important for implementing the security protocol. Thanks to its tree-like structure, establishing contact with the server securely and swiftly has become possible. Moreover, it also makes it convenient to trace back the SSL certificate to its original root.