Piotr Zielinski

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Existing low-latency anonymity networks are vulnerable to traffic analysis, so location diversity of nodes is essential to defend against attacks. Previous work has shown that simply ensuring geographical diversity of nodes does not resist, and in some cases exacerbates, the risk of traffic analysis by ISPs. Ensuring high autonomous-system (AS) diversity(More)
We present an attack on hardware security modules used by retail banks for the secure storage and verification of customer PINs in ATM (cash machine) infrastructures. By using adaptive decimalisation tables and guesses, the maximum amount of information is learnt about the true PIN upon each guess. It takes an average of 15 guesses to determine a four digit(More)
In this paper, we propose a fast search algorithm for a large fuzzy database that stores iris codes or data with a similar binary structure. The fuzzy nature of iris codes and their high dimensionality render many modern search algorithms, mainly relying on sorting and hashing, inadequate. The algorithm that is used in all current public deployments of iris(More)
In the set agreement problem, n processes have to decide on at most n − 1 of the proposed values. This paper considers asynchronous shared-memory systems equipped with an anti-Ω failure detector. Each query to the anti-Ω returns a process id; the specification ensures that there is a correct process whose id is returned only finitely many times. The main(More)
Our understanding of the evolutionary mechanisms generating variation within the highly polymorphic major histocompatibility complex (MHC) genes remains incomplete. Assessing MHC variation across multiple populations, of recent and ancient divergence, may facilitate understanding of geographical and temporal aspects of variation. Here, we applied 454(More)
The optimistic latency of Byzantine Paxos can be reduced from three communication steps to two, without using public-key cryptography. This is done by making a decision when more than (n + 3f)/2 acceptors report to have received the same proposal from the leader, with n being the total number of acceptors and f the number of the faulty ones. No further(More)
The Dining Cryptographers problem studies how to securely compute the boolean-OR function while preserving the privacy of each input bit. Since its first introduction by Chaum in 1988, it has attracted a number of solutions over the past twenty years. In this paper, we propose a new solution: Anonymous Veto Network (or AV-net). Our protocol is provably(More)
The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and(More)
The dining cryptographers network (or DC-net) is a seminal technique devised by Chaum to solve the dining cryptographers problem — namely, how to send a boolean-OR bit anonymously from a group of participants. In this paper, we investigate the weaknesses of DC-nets, study alternative methods and propose a new way to tackle this problem. Our protocol,(More)