Permissions are highly sensitive in Internet-of-Things (IoT) applications, as IoT devices collect our personal data and control the safety of our environment. Rather than simply granting permissions, further constraints shall be imposed on permission usage so as to realize the Principle of Least Privilege. Since IoT devices are physically embedded, they are often accessed in a particular sequence based on their relative physical positions. Monitoring if such sequencing constraints are honoured when IoT devices are accessed provides a means to fence off malicious accesses. This paper proposes a history-based capability system, HCAP, for enforcing permission sequencing constraints in a distributed authorization environment. We formally establish the security guarantees of HCAP, and empirically evaluate its performance.
The author presents the design of an identity-based capability protection system called ICAP, which is aimed at a distributed system in a network environment. The semantics of traditional capabilities are modified to incorporate subject identities. This enables the monitoring, mediating, and recording of capability propagations to enforce security policies. It also supports administrative activities such as traceability. The author has developed an exception-list approach to achieve rapid revocation and the idea of capability propagation trees for complete revocation. Compared with existing capability system designs, ICAP requires much less storage and has the potential of lower cost and better real-time performance. The author proposes to expand R.Y. Kain and C.E. Landwehr's (1987) design taxonomy of capability-based systems to cover a wider range of designs. >