"Ensuring system availability, data integrity and privacy, user authentication and transaction non-repudiation for communications and computer systems that comprise the National Information Infrastructure creates a host of Information Assurance (IA) challenges. One of the foremost of these challenges is the need to connect enterprise systems to external systems while protecting against the threat of external penetration with an adversarial goal of obtaining, manipulating or destroying critical information. The purpose of this Advisory Memorandum is to look at two available tools which are a part of the solution to this challenge."
NSTISSAM COMPUSEC 1-98
Committee on National Security Systems: http://www.cnss.gov