A computationally efficient and secure time scheme for wireless applications

Wireless mobile computing devices are used extensively to access the Internet for critical applications and services, which must be secured by computationally efficient algorithms and schemes. Computationally efficient security schemes, however, require accurate time synchronization between client and application servers, which is very challenging due to its susceptibility to stochastic noise on the transmission path and to message delay attacks where an adversary can intentionally delay measurement messages in order to compromise the scheme. In statistically noisy networks, accurate time synchronization requires filtering of a large number of measurements to reduce stochastic noise. Each measurement must be secured and, therefore, computationally efficient schemes are required to facilitate mobile computing. Efficient security schemes are also required to detect message delay attacks and to authenticate synchronization message sources (e.g. multicast host server and clients). We propose a computationally efficient time synchronization scheme, which achieves accurate and reliable time clock-offset estimates from a single measurement. This approach is based on a per node quality of service scheme, which can be easily incorporated into existing and emerging quality of service scheduling disciplines. It is designed to reduce stochastic noise by providing per node delay guarantee for synchronization. We also propose an efficient and reliable scheme to detect message delay attack. The proposed scheme compares synchronization messages round trip delay with predefined thresholds to ensure that they fall within expected limits, otherwise they are discarded.