OpenSSL Certificate Generation Script

This guide explains how to generate a Certificate Authority (CA), server certificates, and sign them using OpenSSL. The process is automated with a bash script.

Script Overview

The script performs the following tasks:

1. Removes any existing .pem, .csr, and .srl files.
2. Generates a private key and self-signed certificate for the Certificate Authority (CA).
3. Creates a private key and Certificate Signing Request (CSR) for the server.
4. Defines a configuration file for server certificate extensions.
5. Signs the server's CSR with the CA's private key and certificate.
6. Verifies the generated server certificate.

Usage Instructions

1. Download the Script

Save the above script as gen.sh or download the pre-created script: Download gen.sh

2. Make the Script Executable

Run the following command to give the script execute permissions:

chmod +x gen.sh

3. Execute the Script

Run the script to generate the certificates:

./gen.sh

4. Verify Generated Files

The following files will be created:

• ca-key.pem: The CA's private key.
• ca-cert.pem: The CA's self-signed certificate.
• server-key.pem: The server's private key.
• server-cert.csr: The server's Certificate Signing Request (CSR).
• server-cert.pem: The server's signed certificate.

5. Inspect the Certificates

You can inspect the generated certificates and CSR using these commands:

• Inspect the CA certificate:

  openssl x509 -in ca-cert.pem -noout -text

• Inspect the server certificate:

  openssl x509 -in server-cert.pem -noout -text

• Inspect the CSR:

  openssl req -in server-cert.csr -noout -text

Notes

• The script uses a 4096-bit RSA key for enhanced security.
• Ensure the openssl tool is installed and available in your PATH before running the script.
• Update the CASUBJ and SERVERSUBJ variables to match your organization's details.

Troubleshooting

If you encounter errors, ensure:

• You have write permissions in the directory.
• The openssl command is properly installed and configured.

Feel free to modify the script to fit your specific needs.