What is a Certificate Signing Request (CSR)

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A Certificate Signing Request (CSR) is a critical part of securing any SSL/TLS certified website . A CSR is required to protect your users' sensitive information by transmitting encrypted data. It is essentially a block of encrypted text containing sensitive information such as your domain name, organization, and public key.

In this guide, you'll learn everything you need to know about CSRs - from the basics, such as what a CSR is and how it works, to advanced topics, such as creating and submitting a CSR to a Certificate Authority (CA) .

Table of contents

What is a Certificate Signing Request?
Why do you need a certificate signing request?
How does a certificate signing request work?
What information is included in the CSR?
The Role of Public and Private Keys in CSR
How to Generate a Certificate Signing Request
Understanding the Different Types of Certificate Signing Requests
How long is a certificate signing request valid?
What happens after your CSR is approved?
What is a Certificate Signing Request?
A Certificate Signing Request (CSR) is a specially formatted block of text containing key information about your website or organization. It plays a critical role in obtaining an SSL/TLS certificate , which is needed to encrypt communications between a web server and a client (such as a browser).

When you need to secure your site with SSL/TLS , the first step is to generate a CSR. This request is then sent to a Certificate Authority (CA) - a trusted third party responsible for issuing the actual digital certificate . The CSR contains your public key, which is used to establish secure connections, as well as other information about your domain and organization.

By submitting a CSR, you are essentially asking mobile app development service the CA to verify your identity and issue the necessary digital certificate to secure your site. Without this process, your site will not be able to establish secure HTTPS connections , which are essential for protecting user data and improving SEO rankings.

Why do you need a certificate signing request?
A CSR is required whenever you need an SSL/TLS certificate, whether for your website or internal network systems. The reason it is important is simple: an SSL/TLS certificate provides encryption that protects sensitive data transmitted between users and your website. This is especially important for e-commerce sites, financial institutions, or any platform that handles personal information.




Moreover, search engines like Google now give preference to HTTPS sites when ranking, meaning that an SSL certificate can directly improve your SEO. A valid SSL certificate also increases customer trust, as it assures users that their data is secure from eavesdropping or interception. A CSR is the first step to obtaining such a certificate.

How does a certificate signing request work?
The process of requesting a certificate to be signed revolves around a public key infrastructure ( PKI ) . To explain it more simply, here's how it works:

Generate a CSR : This step is done on the server where your website is hosted. You will use a tool (such as OpenSSL ) to generate the CSR file.
Public/Private Key Pair : When you create a CSR, a public key and a private key are generated at the same time. The public key is included in the CSR, and the private key remains secure on your server.
Submit the CSR : The CSR is then sent to a certificate authority (CA) such as Let's Encrypt or DigiCert to verify your identity.