A practical technique for delegation is described. It provides both cryptographic assurance that a delegation was authorized and authentication of the delegated systems, thereby allowing reliable access control as well as precise auditing of the systems involved in every access. It goes further than other approaches for delegation in that it also provides termination of a delegation on demand (as when the user logs out) with the assurance that the delegated systems, if subsequently compromised, cannot continue to act on the user's behalf. Delegation and revocation are provided by a simple mechanism that does not rely on online trusted servers.>

This paper presents a high-level design for a local area network (LAN) that will support subscribers (terminals or hosts) operating at various security levels. Subscribers may be "single-level", which means they are untrusted and can operate at only one security level, or they may be "multilevel" and trusted to operate at a range of security levels [Nibaldi79].