*/
public void checkValidity(Calendar now) throws CertificateExpiredException,
CertificateNotYetValidException {
if (now.before(tbsCertificate_.getNotBefore()))
throw new CertificateNotYetValidException(
"Certificate is not valid yet");
if (now.after(tbsCertificate_.getNotAfter()))
throw new CertificateExpiredException("Certificate is expired");