Operating systems security is relatively new area. Most Operating Systems were designed without adequate attention to security since the primary concerns were economic. In this paper we present a new architecture that facilitates the design of secure time-shared Operating Systems. This approach differs from others that rely on verification to achieve security. In the proposed architecture, encryption is used to enforce the security policies.

This paper presents some of the lessons that we have learned from programming in a message-switched environment, and from the Mininet project in particular. We consider the issues of task programming versus monolithic programs, task invocation versus function call/return, and blocking and non-blocking message-passing primitives.