538 research outputs found
Optimal Active Social Network De-anonymization Using Information Thresholds
In this paper, de-anonymizing internet users by actively querying their group
memberships in social networks is considered. In this problem, an anonymous
victim visits the attacker's website, and the attacker uses the victim's
browser history to query her social media activity for the purpose of
de-anonymization using the minimum number of queries. A stochastic model of the
problem is considered where the attacker has partial prior knowledge of the
group membership graph and receives noisy responses to its real-time queries.
The victim's identity is assumed to be chosen randomly based on a given
distribution which models the users' risk of visiting the malicious website. A
de-anonymization algorithm is proposed which operates based on information
thresholds and its performance both in the finite and asymptotically large
social network regimes is analyzed. Furthermore, a converse result is provided
which proves the optimality of the proposed attack strategy
Seeded Graph Matching: Efficient Algorithms and Theoretical Guarantees
In this paper, a new information theoretic framework for graph matching is
introduced. Using this framework, the graph isomorphism and seeded graph
matching problems are studied. The maximum degree algorithm for graph
isomorphism is analyzed and sufficient conditions for successful matching are
rederived using type analysis. Furthermore, a new seeded matching algorithm
with polynomial time complexity is introduced. The algorithm uses `typicality
matching' and techniques from point-to-point communications for reliable
matching. Assuming an Erdos-Renyi model on the correlated graph pair, it is
shown that successful matching is guaranteed when the number of seeds grows
logarithmically with the number of vertices in the graphs. The logarithmic
coefficient is shown to be inversely proportional to the mutual information
between the edge variables in the two graphs
A New Achievable Rate Region for Multiple-Access Channel with States
The problem of reliable communication over the multiple-access channel (MAC)
with states is investigated. We propose a new coding scheme for this problem
which uses quasi-group codes (QGC). We derive a new computable single-letter
characterization of the achievable rate region. As an example, we investigate
the problem of doubly-dirty MAC with modulo- addition. It is shown that the
sum-rate bits per channel use is achievable using the new scheme.
Whereas, the natural extension of the Gel'fand-Pinsker scheme, sum-rates
greater than are not achievable.Comment: 13 pages, ISIT 201
- β¦