How to Extract a Private Key from a Certificate Using OpenSSL?

You cannot directly extract a private key from a certificate using OpenSSL. Certificates only contain the public key, which is used to verify the authenticity of the corresponding private key.

Here's why:

• Security: Private keys are kept secret and are never stored within certificates. Exposing a private key would compromise the security of the certificate and the associated system.
• Purpose: Certificates are designed to share public keys, allowing others to verify the authenticity of the certificate holder. The private key remains with the certificate owner for signing and decryption purposes.

To access the private key:

• Locate the private key file: The private key is usually stored in a separate file.
• Check file extension: Look for files with extensions like .pem, .key, or .p12.
• Use OpenSSL to extract the private key from the file:

openssl rsa -in private_key.pem -outform PEM -out extracted_key.pem

Important Note: Always handle private keys with extreme care. They should be stored securely and only accessed by authorized individuals.