Security in a distributed message handling system

Considers the message handling system (MHS) as described in the CCITT X.400 Recommendations and looks at security services for such a system. The author gives a brief overview of the MHS architecture and the need for directory services to support these services. He considers a security profile for such a system. In particular, he considers the security threats faced by the system, and the types of security services required to counteract these threats. He also describes the security mechanisms to provide these security services. The security services provided are a subset of the security features outlined in the CCITT 1988 X.400 Recommendations. The use of a formal description technique LOTOS (ISO Standard) for modelling these security aspects is also described