public static CertificateID createCertId(X509Certificate subject,X509Certificate issuer) throws Exception {
  return createCertId(subject.getSerialNumber(),issuer);
}

public static CertificateID createCertId ( X509Certificate subject , X509Certificate issuer ) throws Exception { return createCertId ( subject . getSerialNumber ( ) , issuer ) ; }
creates a new certificate id instance ( using sha - 1 digest calculator ) for the specified subject and issuer certificates .
