Providing Real-time Security Support for Multi-level Ad-hoc Networks Jiejun Kong, Mario Gerla Computer Science Department University of California, Los Angeles {jkong,gerla}@cs.ucla.edu

Real-time Security Support: Characteristics Capable of processing vast amount of data in short period Raises performance concerns on mobile devices This work studies performance aspects of security solutions in mobile ad hoc networks Delay sensitive Packets that incur an extra end-to-end delay are essentially useless Loss-tolerant (nearly solved) Occasional data loss/corruption only causes insignificant glitches Solutions: TESLA, IPsec/ESP What does “adaptive” mean here? ……

Mobile Real-time Applications Mobile real-time data collector Useful in tactical environments, paramedic emergency, news report, personal communications On-device encoding and encryption Motivation 1. Mobile client of multimedia streaming Pocket TV broadcasting On-device decryption and decoding

Application Domain: Digital Battlefields Level 1: Regular Ground Nodes < > Level 3: Aerial Mobile Backbone Level 2: Ground Mobile Backbone

Multi-level Heterogeneous Ad-hoc Networks Problem of homogeneous mobile ad-hoc networks Network capacity approaches 0 when network scale increases Multi-level heterogeneous ad-hoc network provides scalability and throughput guarantees Regular ground nodes Ground mobile backbone (MBN nodes) Aerial mobile backbone structure (UAV nodes) Network capacity approaches the bottleneck link capacity E.g., 11Mbps in 802.11b, 54Mbps in 802.11a

Communication Bandwidth  vs. Computation Bit-rate  Communication bandwidth t Max: W Min: 0 Capacity of a MANET with N nodes: (N) Computation processing bit-rate t Must catch up with t t = t Otherwise packet drop-off or buffer overflow

Communication Bandwidth  vs. Computation Bit-rate  (detail) Major processing overheads come from Operation A: compression (of encoding) Operation B: encryption (of security protection) A is limited due to heavy workload 352x240 resolution image, 24-bit color, 30frame/sec  60Mbps On-device compression 60Mbps  1.5Mbps MPEG stream B is limited due to inflexible encryption schemes designed for large servers When t is at the scale of Mbps speed, can t catch up with t ?

Experiments on Mobile Device iPAQ3670, Intel StrongARM 206MHz CPU, 16M ROM, 64M RAM

Case Study: t <t ok failed Encoding A = 2Mbps. Encryption B = measured previously. Will the overall data rate t reach the line t =1.5Mbps (MPEG I)?

Proposals Call for rate-adaptive security protection Notion of adaptive “real-time” protection Actual protection varies with network condition Yet, a guaranteed lower-bound on protection Data (adaptable rate/content) secured data secret Adaptable strength Adaptable bitrate Security Module (adaptable) (bandwidth estimation etc.) network feedback