In-network aggregation is an efficient and scalable distributed approach to global state approximation. However, security remains an open problem in such systems, especially when we consider dynamic network effects, such as mobility, packet loss and churn. In this paper, we consider the reseilience of the top-k aggregate to manipulation by active insider adversaries. Unfortunately, this versatile aggregation function is inherently insecure. We propose a simple, low-overhead solution to the problem of preserving aggregate integrity which leverages the principles of trusted systems. The solution we propose is generally applicable, even to the challenging problem of securing distributed aggregation in a dynamic network.

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Ad-hoc wireless peer-to-peer methods are an important and viable alternative to the more traditional infrastructure based ones for distributing contents among a population of users. The PodNet project is a ongoing effort to create a broadcasting system for delay-tolerant content, in which peer nodes exchange contents opportunistically when within range, and their mobility acts as a complementary mechanism for the dissemination. This paper introduces the design of a Pod-Net node. In particular, the special case of a gateway, which bridges the infrastructure world of the Internet and the ad-hoc domain, is considered.