Security in distributed computing systems is a very important area of research, especially as malicious behavior is a growing cause of concern for businesses and organizations. This paper addresses an emerging method of maintaining security in untrustworthy environments. Until recently, the operating system was the only means of protecting data; the authors discuss a more elaborate technique of using middleware as a second level of security. "When integrated effectively, this multi-level approach makes it harder for intruders to corrupt or disable distributed systems and applications." The paper is scheduled to appear in 2003; several other papers on related topics can be found on the site's home page.