D11.1: Collection of Topics and Clusters of Mobility and Identity – Towards a Taxonomy of Mobility and Identity

Title: NETWORKS

Mobile ad hoc networks are described in deliverable DD3.3 “Study on Mobile Identity Management” as “mobile platforms or nodes that can move freely and establish ephemera wireless networks without central entities to control it”. By definition (Corson, Macker, 1999), mobile ad hoc networks may operate in isolation – that is, in the absence of any fixed infrastructure. Therefore, the concept of autonomous systems does not exist in mobile ad hoc environments, implying that there is no entity controlling the network and providing services such as routing, security or even addressing.

The aforementioned lack of standardised addressing allows mobile network nodes to easily change their IP and MAC addresses, or even have multiple network interfaces (either real or virtual) with multiple identifiers. Thus, traditional identification in such environments, using network and data link information simply does not work. This might give the impression that nodes in mobile ad hoc network environments are naturally anonymous. However, senders and receivers can still be pinpointed and linked by observers in the network. In addition, having no persistent identities (that is, no mobile idem identities) is harmful for the network sanity in the long run, since it is not possible to identify malicious users in the network. In other words, in the absence of any form of persistent identities, mobile ad hoc networks are highly susceptible to Sybil attacks (Douceur, 2002), in which malicious users assume multiple identities in the network, preventing the usage of security mechanisms based on filters or trust assumptions.

Therefore, in order to provide reliable anonymous communication for network nodes in a mobile ad hoc network, persistent identifiers (i.e. mobile idem identities) are needed in the first place. Although anonymity and identities can be understood as opposites to each other, without identities, reliable anonymity is not achievable in mobile ad hoc environments. We call this situation the identity vs. anonymity paradox. For this reason, as will be described in the next section, most security models for mobile ad hoc networks, in one way or other, are based on the usage of some kinds of digital certificates.