An ad hoc network is a collection of wireless computers (nodes), communicating among themselves over possibly multihop paths, without the help of any infrastructure such as base stations or access points. Although many previous ad hoc network routing protocols have been based in part on distance vector approaches, they have generally assumed a trusted environment. This thesis presents a secure destination-sequenced distance-vector routing protocol (SDSDV) for mobile wireless ad hoc networks. The proposed protocol is based on the regular DSDV protocol. Within SDSDV, each node maintains two one-way hash chains about each node in the network. Two additional fields, which we call alteration field and accumulation field, are added to each entry in an update. With proper use of the elements of the hash chains in AL and AC fields, the sequence number and the metric values on a route can be protected from being arbitrarily tampered. In comparison with the secure efficient distance vector (SEAD) protocol previously proposed in literature provides only lower bound protection on the metric, SDSDV can provide more robust protection. Although SDSDV is more robust than SEAD, it produce higher routing load in updates, especially in a large ad hoc network. According to our simulation, the data packet delivery ratio of SDSDV is smaller than DSDV. So we also consider using public-key encryption instead of symmetric encryption. Our proposed SDSDV using public-key encryption (SDSDV-PK) is based on the characteristics of authentication and integrity inherent in public-key cryptography. The SDSDV-PK also requires one additional field for each entry. The additional field is used for authentication the metric value, sequence number and the authentication value of the other node. We have compared the system performance of SDSDV and SDSDV-PK to the original DSDV by computer simulation. Results show that due to the additional hash fields, the SDSDV exhibits slight worse performance in the Average end-to-end delay of routing packets and routing load. However, we think this worthwhile because by paying the cost we can secure the routing protocol.
