Modeling Context-Adaptive Energy-Aware Security in Mobile Devices

Energy Management is of primary importance in mobile devices due to increasing functionality coupled with rapid battery drain. Our analysis reveals that users differ in context and resource usage patterns which can be leveraged for power savings. A key challenge lies in providing context-adaptive security in an energy aware manner due to increasing sensitivity of user data and analyzing energy-security trade-offs. Towards this challenge, we model the problem of context-adaptive energy-aware security as a knapsack problem and develop a pseudo-polynomial dynamic programming (DP) based framework to maximize user utility corresponding to a power budget. Further, we prove the decision version of the problem to be NP-hard via a reduction from Knapsack and design a greedy heuristic for optimal assignment of security levels towards meeting a given power budget. Finally, we design a Fully Polynomial Time Approximation Scheme (FPTAS) for the problem which improves upon the DP based approach. The proposed mechanisms are optimal in that, they can be used to facilitate efficient allocation of resources pertaining to user needs.