Key propagation in wireless sensor networks

With reference to a network consisting of sensor nodes connected by wireless links, we approach the problem of the distribution of the cryptographic keys. We present a solution based on communication channels connecting sequences of adjacent nodes. All the nodes in a channel share the same key. This result is obtained by propagating the key connecting the first two nodes to all the other nodes in the channel. The key propagation mechanism is also used for key replacement, as is required, for instance, in group communication to support forms of forward and backward secrecy, when a node leaves a group or a new node is added to an existing group

Protected pointers in wireless sensor networks

With reference to a distributed architecture consisting of sensor nodes connected by wireless links in an arbitrary network topology, we consider a segment-oriented implementation of the single address space paradigm of memory reference. In our approach, applications consist of active entities called components, which are distributed in the network nodes. A component accesses a given segment by presenting a handle for this segment. A handle is a form of pointer protected cryptographically. Handles allow an effective implementation of communications between components, and key replacement. The number of messages generated by the execution of the communication primitives is independent of the network size. The key replacement mechanism is well suited to reliable application rekeying over an unreliable network

Key management in wireless sensor networks

We refer to a distributed architecture consisting of sensor nodes connected by wireless links and organized in a tree shaped hierarchy. We present a paradigm for the management of the cryptographic keys used by nodes to communicate, and we consider the problems connected with key generation, distribution, and replacement. In our paradigm, names are assigned to nodes by using a uniform scheme, which is based on the position of the given node in the node hierarchy. Each node holds a hierarchical key to communicate with its ancestors, and a level key to communicate with its siblings. A single, publicly-known parametric one-way function is used to assign hierarchical keys to nodes, in an iterative procedure that starts from the key of the root of the node hierarchy, and proceeds downwards to the lowest hierarchical levels. A similar procedure is used to generate the level keys. The total memory requirements for key storage are extremely low. The number of keys exchanged in a key replacement process is kept to a minimum. Dynamic access control is fully supported, whereby new nodes can be added to the node hierarchy, and existing nodes can be evicted from the hierarchy

Why do users trust the wrong messages? A behavioural model of phishing

Given the rise of phishing over the past 5 years, a recurring question is why users continue to fall for these scams? Various technical countermeasures have been proposed to try and counter phishing, and none have yet comprehensively succeeded in preventing users from becoming victims. This paper argues that an explicit model of user psychology is required to understand user behaviour in (a) processing phishing e-mails, (b) clicking on links to phishing websites, and (c) interacting with these websites. Many users engage in e-mail and web activity with an inappropriately high level of trust: users are constantly rewarded by their online interactions, even where there is a low level of formalised trust between the sending and receiving parties, eg, if an e-mail claims to be sent from a bank, then it must be so, even if there has been no a priori exchange of credentials mediated by a trusted third party. Previously, mathematical models have been developed to predict trust established and maintenance based on reputation scores (e.g., Tran et al [1, 2]). This paper considers two inter-related questions: (a) can we model the behaviour of users learning to trust, based on non-associative models of learning (habituation and sensitisation), and (b) can we then locate this behavioural activity in a broader psychological model with a view to identifying potential countermeasures which might circumvent learned behaviour? © 2009 Crown

Distributed storage protection in wireless sensor networks

With reference to a distributed architecture consisting of sensor nodes connected in a wireless network, we present a model of a protection system based on segments and applications. An application is the result of the joint activities of a set of cooperating nodes. A given node can access a segment stored in the primary memory of a different node only by presenting a gate for that segment. A gate is a form of pointer protected cryptographically, which references a segment and specifies a set of access rights for this segment. Gates can be freely transmitted between nodes, thereby granting the corresponding access permissions. Two special node functionalities are considered, segment servers and application servers. Segment servers are used for inter-application communication and information gathering. An application server is used in each application to support key management and rekeying. The rekey mechanism takes advantage of key naming to cope with losses of rekey messages. The total memory requirements for key and gate storage result to be a negligible fraction of the overall memory resources of the generic network node