Thesis

List of Figures
2.1 Illustration of a key-tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Illustration of single member compromise . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Illustration of several members compromise . . . . . . . . . . . . . . . . . . . . . . 20
2.4 Simulation results for branching factor vectors . . . . . . . . . . . . . . . . . . . . . 22
2.5 system comparison based on approximation . . . . . . . . . . . . . . . . . . . . . . 23
2.6 Operation of the group-based private authentication scheme . . . . . . . . . . . . . 24
2.7 Tree and group based authentication . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.8 Simulation results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.1 Mix and observed zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 Simplified map of Budapest generated for the simulation. . . . . . . . . . . . . . . 35
3.3 Success probabilities of the adversary . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.4 Results of the simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.5 Success rate of a tracking attacker . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.6 Example intersection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.7 Success rate of the simple attacker . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8 Success rate of the simple attacker . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.9 Number of signatures to be verified . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.1 Result of aggregator election protocol . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.2 Probability of being cluster aggregator . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.3 Probability of being cluster aggregator . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4 Result of balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.5 Entropy of the attacker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.6 Connected dominating set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.7 Aggregation example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.8 Query example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.9 Graphical representation of the suitable intervals . . . . . . . . . . . . . . . . . . . 69
4.10 Misbehavior detection algorithm for the query protocol. . . . . . . . . . . . . . . . 71
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