Network Performance Centric Security Design in MANET

Security is a basic requirement for mobile ad hoc networks. Several recent papers [4, 1, 2] have started to address security issues in such networks. While these early proposals each have their own merit, they mainly focus on the security vigor of the design and leave the network performance aspect largely unaddressed. As a result, these solutions may be extremely secure from the cryptographic standpoint, but their real performance when deployed in the network is unclear. This concern is further aggravated by the unique characteristics of ad hoc networks, such as highly dynamic network topology, frequent node arrival/departure, and bandwidth-constrained wireless links. In this work, we shift our main attention from the cryptography-centric design approach to a more networkcentric design scheme, and focus on the practical network performance aspect of the security design. Our goal is to developnetwork performance-centric security solutions that effectively balance security strength and network performance in practice. We focus on node authentication, the basic component in a security solution. At the first stage, we investigate several design choices – centralized, peer-to-peer, and localized authentication schemes, and examine their network performance by extensive simulations. The centralized scheme [4] is similar to the TTP (Trusted Third Party) authentication widely used in the wired networks, in which authentication is done via the third-party certificate authority (CA). The peer-to-peer authentication scheme [1] bears the same philosophy as PGP, where authentication is done through a chain of trust relationship that forms the “web of trust”. The localized scheme [2] is specially designed for ad hoc networks, in which each node is authenticated and monitored by its multiple local neighboring nodes. The simulation results are summarized in Table 1. Scalability: We examine whether the design scales to the number of nodes. The average node speed is 10m/s, and there is no channel error and other ongoing traffic (benchmark setting). When the number of nodes increases from 40 to 100, the success ratio of the authentication request in centralized scheme drops from to ; the success ratio in peer-to-peer scheme remains stable around ; while the success ratio in localized scheme remains stable around . Availability: We increase the network traffic load and examine whether the design provides “anytime, anywhere” security service to the mobile hosts. For a 60-node setting with average speed of 10m/s, when the network traffic load increases from 0 to 100 pkt/s (packet size 512B), the success ratio in centralized schemes drops from to ; the success ratio in peer-to-peer scheme almost remains stable around ; while the success ratio in localized scheme remains stable around . Robustness: We examine the robustness feature for different channel conditions. For the same 60-node setting, when the channel error rate increases from 0 to , the success ratio in centralized scheme drops from to ; the success ratio in peer-to-peer scheme drops from to ; while the success ratio in localized scheme drops from to .