code: static String getDNSubField(String varName, String DN) throws CertificateMapperException {
          if (varName.equals("DN")) {
              return DN; // return the whole DN
          }
          // Parse the DN looking for 'varName'
          StringTokenizer st = new StringTokenizer(DN);
          for (;;) {
              String name, value;
              try {
                  name = st.nextToken(",= ");
                  value = st.nextToken(",");
                  if (value != null) {
                      value = value.substring(1);
                  }
              } catch (NoSuchElementException e) {
                  e.getMessage();
                  break;
              }
              if (name.equals(varName)) {
                  return value;
              }
          }
  
          throw new CertificateMapperException(WIMMessageKey.UNKNOWN_DN_FIELD, Tr.formatMessage(
                                                                                                tc,
                                                                                                WIMMessageKey.UNKNOWN_DN_FIELD,
                                                                                                WIMMessageHelper.generateMsgParms(varName)));
      }
docs: Given 'input', return the digest version.