Server Certificate Vs. Client Certificate – Technical Difference Explained

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Client vs Server Certificate

Comprehensive Overview of Server Certificate vs Client Certificate

Though hosting a website is easy today, there are still some aspects that need the utmost attention. Website security is one of those aspects. Website security deals with the use of SSL certificates, and server certificate vs client certificates is a tough clash.

Why is it a clash? It is because most of us get confused about these SSL certificates. As there are many other types of certificates like root certificate, intermediate certificate, client certificate, etc., their definition and utility can be confusing to comprehend.

In this comprehensive article, we will focus on the analysis and comparison of client certificates and server certificates. So, let’s begin!

What is a Client Certificate?

The core motive of the client certificate is to ensure security. Just like an SSL certificate is important for a website to be legitimate, a client certificate is necessary for a client to be marked as real.

A client certificate refers to a digital certificate that assures the identity of the client trying to access the server. The user can be an email user or a website user.

You can consider it as a password. However, the password can be hacked using various methods by cybercriminals. A client certificate cannot be hacked, and it can seamlessly authenticate the user without any input.

An exemplary explanation of the concept can be the following.

Let’s say you have kept some confidential and sensitive documents on your server, and they can only be accessed by some systems in your organization. As long as the users access the server from that system, they can get the required document or not. These systems have valid client certificates, which is the reason they can easily access sensitive documents.

Tip: To make it more secure, you can add the multi factors integration system on top of the client certificate.

One of the best examples of client certificates is an email (SMIME) client certificate.

How Does Client Certificate Work?

Just like other website security certificates, the client certificate also uses a pair of public and private keys. The private key is with the user and is used to sign the outgoing emails. At the receiver’s end, the public key is used to verify the message and signature.

What is a Server Certificate?

The server certificate is just another name for the SSL certificate used by websites. The server certificate is issued to ensure that all communication between the user and the server is safe and encrypted.

Whenever a user tries to access a website, the browser checks the website for a valid server certificate. An SSL certificate (server certificate) is an X.509 certificate that undertakes two functions!

  1. Before providing authentication, a server certificate checks the identity of the server certificate holder. It can be an organization or an individual.
  2. Once the authentication process is complete, the server certificate encrypts the communication channel and changes the HTTP protocol to HTTPS.

Tip: For your confirmation, you can check the padlock sign just beside the address bar of the browser.

As mentioned above, an example of a server certificate is an SSL or TLS certificate. Website owners can opt for three types of SSL certificates, such as

How Does Server Certificat Work?

The working of a server certificate or an SSL certificate begins with a web browser sending a connection request to the server. Further, the browser also requests the web server for its identity.

In return, the web server sends a copy of its SSL certificate. The web browser verifies the SSL certificate against its certificate store. If the certificate is valid, a message is sent to the server.

The server, in return, sends the digitally signed acknowledgment for the beginning of an encrypted session.

Tip: No matter if you are an organization or an individual user, it is best to go for an extended validation certificate.

Server Certificate vs Client Certificate-The Technical Differences

Before you go to buy any of these two certificates, it is crucial to understand the differences between the two. It will help you buy the most suitable certificate. Here is the server certificate vs client certificate tabular comparison!

Client CertificateServer Certificate
Client certificates are used to verify the entity of the client trying to contact a server.   These certificates act as passwords without any user input.Server certificates are used to verify the legitimacy of the website before establishing a connection.
The client certificate does not provide any kind of encryption or decryption.Server certificates encrypt the communication channel between the client and the server after authentication.
The OID for client authentication is for server authentication is
An email client certificate is the perfect example of a client certificate.An example of a server certificate is an SSL or TLS certificate.


OID is expanded as object identifiers. The X.509 system features a bunch of certificates for various purposes, like low-price SSL certificates, Code signing certificates, Email (SMIME) certificates, etc.

OID is a part of EKU, which is extended key usage. The extended key usage narrates the purpose of the public key contained in the certificate. The object identifiers are used to indicate this purpose.

For example, the OID for code signing is, and that for anyExtendedKeyUsage is OID

Client and Server Certificates for Data Integrity!

Client and server certificates work in perfect collaboration to provide the best security to users online. The process has two parts!

In part 1, website owners obtain the server certificate from a reputed certificate authority like Comodo, Sectigo, and Certera. The Certificate Authority carefully checks every piece of information, such as the organization’s name, domain name, etc., to confirm that the entity is actually a legitimate one. Once the confirmation is done, the server certificate is provided to the entity. This certificate can be served to the users’ browser to prove that the website is safe and legit.

In part 2, the configuration of the website needs to be adjusted so that the user should provide a client certificate. To make it more secure, you can also add multi-factor authentication in which users should provide a username and password for verification.

Client Certificate Vs Server Certificate-The Technical Similarities!

Yes, the client certificate and the server certificate have their differences. However, there are also some minor similarities between the two.

  • Both certificates are based on public key infrastructure (PKI).
  • Both the certificates have ‘Issued To’ and ‘Issued By’ fields.’ These two fields clearly convey the name of the owner and issuing authority.

Which One Do You Need to Protect a Website?

As we have perfectly analyzed the server certificate vs the client certificate, it is time to know which one is the best for you.

If you are a website owner, especially a website dealing with critical information, you need to have an SSL or server certificate. Financial information, like bank accounts, credit card numbers, ATM pins, etc., need to be encrypted before sending them over the network, and a server certificate is a way to do it.

On the other hand, the client certificate is necessary for you if you have a company intranet and want to ensure that everything on your company server is accessed by authenticated personnel. Client certificates are also useful for signing the email before sending them to your contacts to ensure that it is you.

Client Cert vs Server Cert — Where to Buy?

If you want to buy a client certificate or a server certificate, many legitimate certificate authorities can help you. However, if you are looking for affordable rates as well as the utmost utility, you can rely on

You can easily obtain all types of SSL certificates and client certificates. The price for a client certificate begins from $7.99. On the other hand, the price for a server certificate starts from $2.99.


In the wrap-up, we can say that both server certificates and client certificates are an essential part of the public key infrastructure. Both of them play their individual role, ensuring the authentication of the client and the website. The server certificate vs client certificate comparison shows some chief differences between the certificates. Therefore, if you need to buy one, keep these differences in mind to make an informed choice.

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Janki Mehta

Janki Mehta

Janki Mehta is a Cyber-Security Enthusiast who constantly updates herself with new advancements in the Web/Cyber Security niche. Along with theoretical knowledge, she also implements her practical expertise in day-to-day tasks and helps others to protect themselves from threats.

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