The miniaturization of computing devices and the need for ubiquitous communication has augmented the demand for pervasive computing. Security demands that all devices in a pervasive system must be able to authenticate each other and communicate in a secure manner. This is usually achieved through a Trusted Third Party like a Public Key Infrastructure (PKI) or a Key Distribution Centre (KDC). The establishment of such an entity in such a dynamic environment is neither feasible nor pragmatic. In this paper we present a novel mechanism for authentication and key exchange that can operate seamlessly in pervasive computing environments without the presence of a Trusted Third Party. The proposed scheme has minimal computational requirements, which makes it most suitable for devices with limited resources. 1. Security Scheme for Pervasive Systems ID-based systems [1] were introduced in order to avoid the explicit authentication of public keys through digital certificates. These systems aim at using the identity of a user to represent the public key. The advantage of such systems is that the public key certificates are no longer required to be maintained at a central or distributed trusted third party [2] providing elevated security and efficiency. Such schemes can be configured to perform authentication as well as key exchange without a trusted third party. We propose using the scheme by Sheih et al. [3] for pervasive computing environments because of its simplicity, lower computational overhead and minimal reliance on a central trust authority. The scheme, when configured for a pervasive system, works in three

The paper reviews the most popular peer-to-peer key management protocols used for mobile ad hoc networks (MANETs) with respect to their suitability for military type applications. The protocols are subdivided into groups based on there design strategy. It discusses and provides comments on the strategy of each group separately. The discussions give insight into open research problems in the field of pairwise key management. The conclusion drawn from the review is that the currently available protocols cannot provide the level of security needed in military type MANETs. We propose a fundamental change in the current design strategy: new schemes should make use of an off-line trusted third party (TTP) as the root of the system security, while eliminating the need for any form of on-line TTP. I.