code: public static String getUniqueKey(X509Certificate cert) {
          // TBD - Would like to use public key instead of subject name, but
          // cert.getPublicKey().getEncoded() appears to return different
          // values for each call, using the same certificate??
          StringBuffer key = new StringBuffer("subjectDN:");
          key.append(cert.getSubjectX500Principal().getName()).append("issuerDN:").append(cert.getIssuerX500Principal().getName());
          // TODO::
          // return Base64Coder.base64Encode(getDigest(key.toString()));
          return null;
      }
docs: Get a unique key for a certificate.