What Is a Certificate Signing Request (CSR)

A Certificate Signing Request (CSR) is a critical part of securing any website with an SSL/TLS certificate. A CSR is necessary to protect your users’ sensitive information through encrypted data transmission. Essentially, it’s a block of encrypted text that contains important details like your domain name, organization, and public key.

In this guide, you’ll learn everything you need to know about CSRs—from the basics like what a CSR is and how it works to advanced topics like generating and submitting a CSR to a Certificate Authority (CA).

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Table of Contents

1. What is a Certificate Signing Request?
2. Why Do You Need a Certificate Signing Request?
3. How Does a Certificate Signing Request Work?
4. What Information is Included in a CSR?
5. The Role of Public and Private Keys in a CSR
6. How to Generate a Certificate Signing Request
7. Understanding Different Types of Certificate Signing Requests
8. How Long is a Certificate Signing Request Valid?
9. What Happens After Your CSR is Approved?

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What is a Certificate Signing Request?

A Certificate Signing Request (CSR) is a specially formatted block of text that contains key information about your website or organization. It plays a crucial role in obtaining an SSL/TLS certificate, which is essential for encrypting communications between a web server and a client (like a browser).

When you need to secure your website with SSL/TLS, the first step is generating 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 details about your domain and organization.

By submitting a CSR, you’re essentially asking the CA to verify your identity and issue the necessary digital certificate to secure your website. Without this process, your website wouldn’t be able to establish secure HTTPS connections, which are vital for protecting user data and boosting SEO rankings.

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Why Do You Need a Certificate Signing Request?

A CSR is necessary whenever you need an SSL/TLS certificate, whether for your website or internal network systems. The reason it’s so important is simple: an SSL/TLS certificate provides encryption, which protects sensitive data transmitted between users and your site. This is especially important for eCommerce websites, financial institutions, or any platform that handles personal information.

Moreover, search engines like Google now prioritize sites with HTTPS in their rankings, meaning an SSL certificate can directly improve your SEO performance. A valid SSL certificate also boosts customer trust, as it assures users that their data is safe from eavesdropping or interception. The CSR is the first step in obtaining that certificate.

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How Does a Certificate Signing Request Work?

The process of a Certificate Signing Request revolves around public key infrastructure (PKI). To explain it simply, here’s how it works:

1. Generate a CSR: This step happens on the server where your website is hosted. You’ll use a tool (like OpenSSL) to generate a CSR file.
2. Public and Private Key Pair: When creating a CSR, a public key and private key are generated simultaneously. The public key goes into the CSR, while the private key stays secure on your server.
3. Submit the CSR: The CSR is then submitted to a Certificate Authority (CA), such as Let’s Encrypt or DigiCert, to validate your identity.
4. Verification: The CA verifies the information in your CSR. For Domain-Validated (DV) certificates, this might be a simple check of domain ownership, while Organization-Validated (OV) and Extended Validation (EV) certificates require more thorough validation.
5. Certificate Issuance: Once verified, the CA issues an SSL/TLS certificate, which is installed on your server. This allows your website to securely transmit data over HTTPS.

This workflow ensures that the public key in your CSR matches the private key on your server, making it impossible for unauthorized parties to decrypt sensitive data.

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What Information is Included in a CSR?

A Certificate Signing Request contains several pieces of important information, which are vital for creating an SSL certificate:

• Common Name (CN): The fully qualified domain name (FQDN) of your website, such as www.example.com.
• Organization (O): The legal name of your company or organization.
• Organizational Unit (OU): The department within the organization responsible for managing the certificate (this field is optional).
• Country (C): The two-letter code for your country, such as “US” for the United States.
• State/Province (S): The full name of the state or province.
• Locality (L): The city or town where your business is located.
• Email Address (optional): Some CSRs may include an email address for communication purposes.
• Public Key: This is the most crucial part of the CSR. The public key is embedded into the certificate for encryption and secure communication with clients.

All of this information is encoded in the CSR, which is then digitally signed using the private key to ensure its authenticity.

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The Role of Public and Private Keys in a CSR

When creating a CSR, the relationship between public and private keys is essential for security. Here’s how it works:

• Public Key: The public key is included in the CSR and will be part of your SSL/TLS certificate. It’s used to encrypt data that is sent to your server. Anyone can access the public key, but only the corresponding private key can decrypt the information.
• Private Key: This stays on your server and should never be shared. It’s used to decrypt the data encrypted by the public key. If anyone else gains access to your private key, they could potentially decrypt sensitive information, which is why securing the private key is paramount.

In essence, the public key encrypts information, while the private key decrypts it. The CSR ensures that your public key is valid and verifiable by the Certificate Authority, which then issues your SSL certificate.

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How to Generate a Certificate Signing Request

Generating a Certificate Signing Request (CSR) depends on the server environment you are using. Below are some common methods for creating a CSR:

OpenSSL (Linux/Unix-based servers)

OpenSSL is one of the most popular tools for generating CSRs and private keys. Here’s a step-by-step example:

1. Run the following command to generate the CSR:
   
   openssl req -new -newkey rsa:2048 -nodes -keyout yourdomain.key -out yourdomain.csr
2. This command will generate two files:
   
   yourdomain.key: The private key.
   yourdomain.csr: The Certificate Signing Request.
3. You’ll be prompted to fill in details like your domain name (CN), organization, and country.

cPanel (Web hosting environments)

Many shared hosting platforms, like those using cPanel, provide a built-in CSR generation tool:

1. Log into cPanel and go to the SSL/TLS section.
2. Click on Generate a New CSR.
3. Fill out the form with your domain name and organization information.
4. After generating the CSR, download it, along with the private key.

Windows Server

If you’re using Windows Server with IIS (Internet Information Services), the IIS Manager offers a straightforward way to create a CSR:

1. Open IIS Manager and navigate to your server.
2. In the Server Certificates section, select Create Certificate Request.
3. Fill in the required fields like domain name, organization, and public key size.
4. Save the CSR file for submission to a Certificate Authority.

These are just a few methods for generating a CSR, but the basic process is similar across platforms: you input your domain and organization details, generate a CSR, and then submit it to a Certificate Authority.

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Understanding Different Types of Certificate Signing Requests

There are several types of SSL certificates, each with different levels of validation. These differences affect the CSR requirements, but the basic structure remains the same:

Domain-Validated (DV) Certificates:

• Requires minimal verification—just proof that you control the domain name.
• Typically uses a CSR with only the Common Name (CN) (the domain name).
• Best for small websites or blogs that don’t handle sensitive information.

Organization-Validated (OV) Certificates:

• In addition to proving domain ownership, the Certificate Authority (CA) will validate your organization’s legal existence.
• The CSR includes organization details, such as company name and address.
• Ideal for businesses that handle user data but don’t require the highest level of validation.

Extended Validation (EV) Certificates:

• The highest level of SSL validation.
• Requires extensive verification of both the domain name and the organization.
• Your CSR must include detailed organization information.
• Typically used by financial institutions, large corporations, and eCommerce websites.

Each of these certificate types serves different purposes, but they all start with generating a CSR and submitting it for validation.

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How Long is a Certificate Signing Request Valid?

A Certificate Signing Request does not have a specific expiration date, but its relevance is tied to the validity of the SSL certificate. Typically, an SSL certificate is valid for one or two years, after which it must be renewed.

When renewing an SSL certificate, it’s often best to generate a new CSR to ensure the most secure encryption practices. Some hosting platforms or CAs might encourage the use of new CSRs upon renewal for added security.

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What Happens After Your CSR is Approved?

Once your Certificate Signing Request is approved and the SSL certificate is issued by the Certificate Authority (CA), the next step is installation. Here’s what happens after approval:

1. Install the SSL Certificate: After receiving the certificate, install it on your web server. The exact process depends on your server type, but this typically involves uploading the certificate files through cPanel or manually via SSH for Linux-based servers.
2. Configure HTTPS: Ensure that your website is configured to use HTTPS. This may require updating your website’s internal links and setting up automatic redirects from HTTP to HTTPS.
3. Test the SSL Certificate: After installation, verify that the SSL certificate is working properly by visiting your site using HTTPS and using tools like SSL Labs’ SSL Test to check for configuration errors.

Maintaining your SSL certificate is important for the ongoing security and trustworthiness of your website.

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Bottom Line

A Certificate Signing Request (CSR) is the first and crucial step in securing your website with an SSL/TLS certificate. By properly generating a CSR, you ensure that your SSL certificate is issued correctly, helping to protect your visitors’ sensitive information and build trust.

At SSL Dragon, we offer a wide range of affordable SSL certificates from trusted Certificate Authorities, and our step-by-step guides make it easy to generate, submit, and install your SSL certificate hassle-free. Secure your website today with SSL Dragon and keep your data safe with the right SSL solution for your needs.