title: Trying to refresh 'expired' keystore
body: <p>I am trying to re-sign some jars using the ant task 'signjar' however it's telling me "The signer certificate has expired."</p>
  
  <p>So I tried to re-generate the keystore hoping this would 'un-expire' it...</p>
  
  <p><code>keytool -genkey -keystore mykeystore -alias myalias</code></p>
  
  <p>but after entering the keystore password i get: "keytool error: java.lang.Exception: Key pair not generated, alias  already exists"</p>
  
  <p>what am i doing wrong? do i need to delete the keystore to re-generate it or is there a simple way to refresh it so it's not expired?</p>
  
  <p>thanks.</p>