Finding and Resolving Security Misusability with Misusability Cases

Although widely used for both security and usability concerns, scenarios used in security design may not necessarily inform the design of usability, and vice- versa. One way of using scenarios to bridge security and usability involves explicitly describing how design deci- sions can lead to users inadvertently exploiting vulnera- bilities to carry out their production tasks. This paper describes how misusability cases, scenarios that describe how design decisions may lead to usability problems sub- sequently leading to system misuse, address this problem. We describe the related work upon which misusability cases are based before presenting the approach, and illus- trating its application using a case study example. Finally, we describe some findings from this approach that further inform the design of usable and secure systems

High-rate quantum cryptography in untrusted networks

We extend the field of continuous-variable quantum cryptography to a network formulation where two honest parties connect to an untrusted relay by insecure quantum links. To generate secret correlations, they transmit coherent states to the relay where a continuous-variable Bell detection is performed and the outcome broadcast. Even though the detection could be fully corrupted and the links subject to optimal coherent attacks, the honest parties can still extract a secret key, achieving high rates when the relay is proximal to one party, as typical in public networks with access points or proxy servers. Our theory is confirmed by an experiment generating key-rates which are orders of magnitude higher than those achievable with discrete-variable protocols. Thus, using the cheapest possible quantum resources, we experimentally show the possibility of high-rate quantum key distribution in network topologies where direct links are missing between end-users and intermediate relays cannot be trusted.Comment: Theory and Experiment. Main article (6 pages) plus Supplementary Information (additional 13 pages

A Flexible and Dynamic Access Control Policy Framework for an Active Networking Environment

To provide security for active networking nodes with respect to availability and controlled access the introduction of an access control mechanism and consequently a policy framework are mandatory. We follow the approach of a scenario-tailored runtime supervision of the service. During the development of the access control mechanism we strongly focused on keeping the mechanism as efficient as possible and to realize a modular design which allows to dynamically upgrade and configure the mechanism making use of the active networking technology itself while at the same time ensuring that mandatory security checks cannot be circumvented. Each service has to pass initial checks before it could be executed on an active node. Furthermore, also service-specific adaptive criterions could be included into the initial check

Type capabilities for object-oriented programming languages

Capabilities are used to control access to system resources. In modern programming languages that execute code with different levels of trust in the same process, the propagation of such capabilities must be controlled so that they cannot unintentionally be obtained by unauthorised code. In this paper, we present a statically-checked type system for object-oriented programming languages which guarantees that capabilities are restricted to authorised code. Capabilities are regarded as types that are granted to code based on a user-defined policy file (similar to that used by Java). In order to provide a finer-grained access control, the type system supports parameterised capabilities to more precisely identify system resources. The approach is illustrated using file-access examples