Browsing by Author "Arbaugh, William"
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Item Bootstrapping Security Associations for Routing in Mobile Ad-Hoc Networks(2002) Bobba, Rakesh B.; Eschenauer, Laurent; Gligor, Virgil D.; Arbaugh, William; ISRAbstractTo date, most solutions proposed for secure routing in mobile, ad-hoc networks (MANETs) assume that secure associations between pairs of nodes can be established on-line; e.g., by a trusted third party, by distributed trust establishment. However, establishing such security associations, with or without trusted third parties, requires reliance on routing layer security. In this paper, we eliminate this apparent cyclic dependency between security services and secure routing in MANETs and show how to bootstrap security for the routing layer. We use the notion of statistically unique and cryptographically verifiable (SUCV) identifiers to implement a secure binding between IP addresses and keys that is independent of any trusted security service. We illustrate our solution with the Dynamic Source Routing (DSR) protocol and argue that the solution is applicable to other protocols such as SEAD and Ariadne. We evaluate the cost of the DSR solution with simulations over ns-2 and present some preliminary results.Index Termsobile ad-hoc networks, routing, security, DSR
Item An Empirical Analysis of the IEEE 802.11 MAC Layer Handoff Process(2002-09-18) Mishra, Arunesh; Shin, Minho; Arbaugh, WilliamIEEE 802.11 based wireless networks have seen rapid growth and deployment in the recent years. Critical to the 802.11 MAC operation, is the handoff function which occurs when a mobile node moves its association from one access point to another. In this paper, we present an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components. In particular, we show that a MAC layer function - probe is the primary contributor to the overall handoff latency. In our study, we observe that the latency is significant enough to affect the quality of service for many applications (or network connections). Further we find a large variation in the latency with from one handoff to another and also among APs and STAs used from different vendors. In this study, we account for this variation and also draw the guidelines for future handoff schemes. (Also UMIACS-TR-2002-75)Item Improving the Latency of 802.11 hand-offs using Neighbor Graphs(2004-01-29) Shin, Minho; Mishra, Arunesh; Arbaugh, WilliamThe 802.11 IEEE Standard has enabled low cost and effective wireless LAN services (WLAN). With the sales and deployment of WLAN based networks exploding, many people believe that they will become the fourth generation cellular system (4G) or a major portion of it. However, the small cell size of WLAN networks creates frequent hand-offs for mobile users. If the latency of these hand-offs is high, as previous studies have shown, then the users of synchronous multimedia applications such as voice over IP (VoIP) will experience excessive jitter. The dominating factor in WLAN hand-offs has been shown to be the discovery of the candidate set of next access points. In this paper, we describe the use of a novel and efficient discovery method using neighbor graphs and overlap graphs. Our method reduces the total number probed channels as well as the total time spent waiting on each channel. Our implementation results show that this approach reduces the overall probe time significantly when compared to other approaches. Furthermore, simulation results show that the effectiveness of our method improves as the number of non-overlapping channels increases, such as in the 5 GHz band used by the IEEE 802.11a standard. (UMIACS-TR-2003-118)