title: Can I modify a private key validity?
body: <p>I'm a newbie in computer security and I have a basic question whose answer I've not been able to find out.</p>
  
  <p>I have a private key whose validity period has expired. Using that key I'd previously generated a .csr and sent it to a CA and they'd given me a certificate that's still valid.</p>
  
  <p>My question is, can I (using keytool or whatever...) modify the private key's expiration date in order to use it with my certificate (.cer). Could I regenerate a private key to be used with this certificate?</p>
  
  <p>Thank you,</p>