code: public static String changePassword(BrokerSession session, String oldPassword, String newPassword) {
          String cipherKey = session.getServerCaps().getCipherKey();
          String result = session.callRPC("RGNETBRP CVC", encrypt(oldPassword, cipherKey), encrypt(newPassword, cipherKey));
          return result.startsWith("0") ? null : StrUtil.piece(result, StrUtil.U, 2);
      }
docs: Change a password.
  
  @param session Broker session.
  @param oldPassword Old password.
  @param newPassword New password.
  @return Status message from server.