Tip: Add Password Into Existing Private Keys

Add Password:

openssl rsa -aes256 -in your-private-key.pem -out your-private-key-encrypted.pem
writing RSA key
Enter PEM pass phrase:   ****
Verifying - Enter PEM pass phrase: ****

Remove Password:

openssl rsa -in  your-private-key-encrypted.pem -out your-private-key.pem
Private key passphrase:  ****