European Context-awareness and Trust (eurocat09) 3 Rd Workshop on Combining Context with Trust, Security, and Privacy Program Commitee Trust Management in Context-aware and Service-oriented Architectures (invited Talk) Context-aware Identity Delegation

In emerging ubiquitous computing, related nomadic users often perform similar tasks and share the same computing infrastructure. This means that security of the shared resources is of prime importance. Frequent delegation of tasks among users must be anticipated as most nomadic environments are hectic and very dynamic. A delegation mechanism with a slightly complicated user interface will not only reduce the productivity but also provide nomadic users with a strong motivation to circumvent the mechanism itself. Delegation in access control domain is not practical for the most of nomadic users due to its complicated and complex structure. Identity delegation at authentication level provides improved usability, which reduces the risk of circumventing the delegation mechanism; at the same time, however, identity delegation violates the principle of least privileges. We use contextual information of a delegatee to mitigate this violation, which helps to achieve a higher level of practical security in nomadic environments.