Generating a CSR for an S/MIME Personal certificate using OpenSSL – Openprovider

Openprovider’s SSL panel currently does not support generating a CSR for S/MIME Personal Certificates, which requires an email address in the ‘Common Name’ field. OpenSSL is a versatile command-line tool widely used across UNIX, Linux, BSD, and Windows systems for managing cryptographic operations. This guide outlines the steps to create a private key and CSR, essential for obtaining an email signing certificate (also known as an S/MIME or client certificate).

Prerequisites

Ensure OpenSSL is installed on your system.
Create a secure directory to store your private key and CSR files.
Protect this directory to prevent unauthorized access.

Step-by-Step Instructions

Open the Terminal
Launch the terminal application on your computer.
Generate the Private Key and CSR
Execute the following command:
```
openssl req -nodes -newkey rsa:2048 -keyout certificate.key -out certificate.csr
```
This command creates a 2048-bit RSA private key (certificate.key) and a CSR (certificate.csr).
Provide Certificate Details
You'll be prompted to enter the following information:
- - Country Name (2-letter code): e.g., NL
  - State or Province Name: e.g., Gelderland
  - Locality Name: e.g., Nijmegen
  - Organization Name: e.g., Your Company Name
  - Organizational Unit Name: e.g., IT Department
  - Common Name: Your Email address for which the S/MIME Personal certificate to be generated
  - Email Address: Contact point of the certificate owner e.g., john.doe@example.com
  - Challenge Password (Optional): (Leave blank)
  - Optional Company Name: (Leave blank)

Review and Save the CSR
The certificate.csr file is now created in your current directory. Open this file with a text editor and copy its entire contents, including the -----BEGIN CERTIFICATE REQUEST----- and -----END CERTIFICATE REQUEST----- lines.
Submit the CSR
Paste the copied CSR into the appropriate field during the certificate ordering process on your Openprovider SSL panel.

After purchasing the certificate please refer https://support.openprovider.eu/hc/en-us/articles/360021411713-How-to-generate-Public-Key-PFX to generate a PFX certificate using OpenSSL to use with email client like outlook.

Note: Always keep your private key (certificate.key) secure and never share it.