Research Trends in MANETs at CIIT, Islamabad Mohammad Mahboob Yasin, PhD COMSATS Institute of Information Technology

Securing End-to-End Communication Establishing a key between source & destination nodes Find number of disjoint paths ‘n’ Generate ‘n’ shares of a symmetric key Send a share on each disjoint path Assemble at destination ‘n’-1 nodes are compromised?

Securing Group Communication Establishing pair-wise key Diffie-Hellman is too expensive! Give a master key when deploying –If a node is compromised? Delete master key soon after deployment –Adding new nodes later on? –Pre-compute challenge response pairs Node Migration

Group Membership Testing List of members Accumulators –Hash of list --- but quasi-commutative f (f (x, y1), y2) = f (f (x, y2), y1) = A –x is secret, f (x, y1) is witness of y2 –Members can verify each other –Based on modular exponentiation –Computationally expensive –Witness updates are frequent

Subscription Management List of subscribers & expiry dates Can we use an accumulator? –Only moderator needs to Add / Delete Members Verify Membership Verify Validity Period Extend to Sensors? –Nodes maintain list of friends –Authenticate then Add

Message Authentication (broadcast / multicast) Sign each message –Expensive Sign a group of messages –Chain messages –Delay in assembling a group Wireless medium is lossy –Star –Merkle Tree –Multiple Chaining –Distillation Codes –Accumulators?

Malicious Activity in MANETs Malicious nodes may –Drop packets –Reorder packets –Insert bogus packets –Announce false routes Conservation of flow --- reliable networks Model ‘normal’ losses of a MANET Excessive loss --- malicious activity

Delay Tolerant Networks End-to-end connection may never be present Intermediate nodes take custody of messages Links & nodes are inherently unreliable Routing?

Monitoring Quality of Service of Cellular Service Providers

QoS (Technical) Network Accessibility Service Accessibility (CBR) Call Setup Time Service Retainability (CDR) Speech Quality (MOS)

Measuring QoS Practice in vogue –Try to call some destination & observe Can not do too often Loads the network & distorts the results –View Call Data Record (CDR) Very brief calls --- assume failed Network availability not visible Proposed –Monitor RA channel –Follow a call and monitor signal strength –Monitor call set-up time