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We present a simple risk-analysis based method for studying the security of institutions against rational (gain-oriented) attacks. Our method uses a certain refined form of attack-trees that are used to estimate the cost and the success probability of attacks. We use elementary game theory to decide whether the system under protection is a realistic target(More)
It is almost a folklore-knowledge that hash-based time-stamping schemes are secure if the underlying hash function is collision-resistant but still no rigorous proofs have been published. We try to establish such proof and conclude that the existing security conditions are improper because they ignore precomputations by adversaries. After analyzing a(More)
We discuss the availability questions that arise when digital time stamps are used for preserving the evidentiary value of electronic documents. We analyze the time-stamping protocols known to date and point out some weaknesses that have not been addressed so far in scientific literature. Without addressing and solving them, any advantage of the(More)
We present a Universally Composable (UC) time-stamping scheme based on universal one-way hash functions. The model we use contains an ideal auditing functionality, the task of which is to check that the rounds' digests are correctly computed. Our scheme uses hash-trees and is just a slight modification of the known schemes of Haber-Stornetta and Benaloh-de(More)
In this paper, we demonstrate the formal verification of a parameterized asynchronous circuit which has request and acknowledgment controls through data paths. We propose a new encoding technique of the data path and construct a finite abstracted model. The properties expressed by ACTL formulas are model-checked in the abstracted model, and then the(More)
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