33,020 research outputs found
Distributed anonymous discrete function computation
We propose a model for deterministic distributed function computation by a
network of identical and anonymous nodes. In this model, each node has bounded
computation and storage capabilities that do not grow with the network size.
Furthermore, each node only knows its neighbors, not the entire graph. Our goal
is to characterize the class of functions that can be computed within this
model. In our main result, we provide a necessary condition for computability
which we show to be nearly sufficient, in the sense that every function that
satisfies this condition can at least be approximated. The problem of computing
suitably rounded averages in a distributed manner plays a central role in our
development; we provide an algorithm that solves it in time that grows
quadratically with the size of the network
Impossibility of Gathering, a Certification
Recent advances in Distributed Computing highlight models and algorithms for
autonomous swarms of mobile robots that self-organise and cooperate to solve
global objectives. The overwhelming majority of works so far considers handmade
algorithms and proofs of correctness. This paper builds upon a previously
proposed formal framework to certify the correctness of impossibility results
regarding distributed algorithms that are dedicated to autonomous mobile robots
evolving in a continuous space. As a case study, we consider the problem of
gathering all robots at a particular location, not known beforehand. A
fundamental (but not yet formally certified) result, due to Suzuki and
Yamashita, states that this simple task is impossible for two robots executing
deterministic code and initially located at distinct positions. Not only do we
obtain a certified proof of the original impossibility result, we also get the
more general impossibility of gathering with an even number of robots, when any
two robots are possibly initially at the same exact location.Comment: 10
Still Wrong Use of Pairings in Cryptography
Several pairing-based cryptographic protocols are recently proposed with a
wide variety of new novel applications including the ones in emerging
technologies like cloud computing, internet of things (IoT), e-health systems
and wearable technologies. There have been however a wide range of incorrect
use of these primitives. The paper of Galbraith, Paterson, and Smart (2006)
pointed out most of the issues related to the incorrect use of pairing-based
cryptography. However, we noticed that some recently proposed applications
still do not use these primitives correctly. This leads to unrealizable,
insecure or too inefficient designs of pairing-based protocols. We observed
that one reason is not being aware of the recent advancements on solving the
discrete logarithm problems in some groups. The main purpose of this article is
to give an understandable, informative, and the most up-to-date criteria for
the correct use of pairing-based cryptography. We thereby deliberately avoid
most of the technical details and rather give special emphasis on the
importance of the correct use of bilinear maps by realizing secure
cryptographic protocols. We list a collection of some recent papers having
wrong security assumptions or realizability/efficiency issues. Finally, we give
a compact and an up-to-date recipe of the correct use of pairings.Comment: 25 page
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SAnoVs: Secure Anonymous Voting Scheme for clustered ad hoc networks
In this paper we propose a secure anonymous voting scheme (SAnoVS) for re-clustering in the ad-hoc network. SAnoVS extends our previous work of degree-based clustering algorithms by achieving anonymity and confidentiality of the voting procedure applied to select new cluster heads. The security of SAnoVS is based on the difficulty of computing discrete logarithms over elliptic curves, the intractability of inverting a one-way hash function and the fact that only neighboring nodes contribute to the generation of a shared secret. Furthermore, we achieve anonymity since our scheme does not require any identification information as we make use of a polynomial equation system combined with pseudo-random coordinates. The security analysis of our scheme is demonstrated with several attacks scenarios.examined with several attack scenarios and experimental results
CryptoMaze: Atomic Off-Chain Payments in Payment Channel Network
Payment protocols developed to realize off-chain transactions in Payment
channel network (PCN) assumes the underlying routing algorithm transfers the
payment via a single path. However, a path may not have sufficient capacity to
route a transaction. It is inevitable to split the payment across multiple
paths. If we run independent instances of the protocol on each path, the
execution may fail in some of the paths, leading to partial transfer of funds.
A payer has to reattempt the entire process for the residual amount. We propose
a secure and privacy-preserving payment protocol, CryptoMaze. Instead of
independent paths, the funds are transferred from sender to receiver across
several payment channels responsible for routing, in a breadth-first fashion.
Payments are resolved faster at reduced setup cost, compared to existing
state-of-the-art. Correlation among the partial payments is captured,
guaranteeing atomicity. Further, two party ECDSA signature is used for
establishing scriptless locks among parties involved in the payment. It reduces
space overhead by leveraging on core Bitcoin scripts. We provide a formal model
in the Universal Composability framework and state the privacy goals achieved
by CryptoMaze. We compare the performance of our protocol with the existing
single path based payment protocol, Multi-hop HTLC, applied iteratively on one
path at a time on several instances. It is observed that CryptoMaze requires
less communication overhead and low execution time, demonstrating efficiency
and scalability.Comment: 30 pages, 9 figures, 1 tabl
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