3,385 research outputs found
Cross Chain Atomic Swaps in the Absence of Time via Attribute Verifiable Timed Commitments
A Hash Time Lock Contract (HTLC) is a protocol that is commonly used to exchange payments across different blockchains. Using HTLC as a building block for cross blockchain atomic swaps has its drawbacks: The notion of time is handled differently in each blockchain, be it private or public. Additionally, if the swap ends up aborted, the funds are locked in escrow until the safety timeout expires.
In this work we formulate a new cryptographic primitive: Attribute Verifiable Timed Commitment which enables to prove that a timed commitment commits to a value which possesses certain attributes. Using our cryptographic primitive, we describe a new cross chain atomic swap protocol that operates without blockchain derived time and unlike the state of the art, all parties can instantly abort the swap without waiting for the safety timeouts to expire.
In order to prove in zero knowledge that a secret committed to using a timed commitment has a claimed hash value, we employ the MPC in the head technique by Ishai et al. and implement our zero-knowledge proof protocol and evaluate its performance. As part of our techniques, we develop a novel and efficient procedure for integer Lower-Than validation in arithmetic circuits which may be of independent interest
Automatic analysis of distance bounding protocols
Distance bounding protocols are used by nodes in wireless networks to
calculate upper bounds on their distances to other nodes. However, dishonest
nodes in the network can turn the calculations both illegitimate and inaccurate
when they participate in protocol executions. It is important to analyze
protocols for the possibility of such violations. Past efforts to analyze
distance bounding protocols have only been manual. However, automated
approaches are important since they are quite likely to find flaws that manual
approaches cannot, as witnessed in literature for analysis pertaining to key
establishment protocols. In this paper, we use the constraint solver tool to
automatically analyze distance bounding protocols. We first formulate a new
trace property called Secure Distance Bounding (SDB) that protocol executions
must satisfy. We then classify the scenarios in which these protocols can
operate considering the (dis)honesty of nodes and location of the attacker in
the network. Finally, we extend the constraint solver so that it can be used to
test protocols for violations of SDB in these scenarios and illustrate our
technique on some published protocols.Comment: 22 pages, Appeared in Foundations of Computer Security, (Affiliated
workshop of LICS 2009, Los Angeles, CA)
Timed Atomic Commitment
In a large class of hard-real-time control applications, components execute concurrently on distributed nodes and must coordinate, under timing constraints, to perform the control task. As such, they perform a type of atomic commitment. Traditional atomic commitment differs, however, because there are no timing constraints; agreement is eventual. We therefore define timed atomic commitment (TAC) which requires the processes to be functionally consistent, but allows the outcome to include an exceptional state, indicating that timing constraints have been violated. We then present centralized and decentralized protocols to implement TAC and a high-level language construct that facilitates its use in distributed real-time programming
Timed Atomic Commitment
In a large class of hard-real-time control applications, components execute concurrently on distributed nodes and must coordinate, under timing constraints, to perform the control task. As such, they perform a type of atomic commitment. Traditional atomic commitment differs, however, because there are no timing constraints; agreement is eventual. We therefore define timed atomic commitment (TAC) which requires the processes to be functionally consistent, but allows the outcome to include an exceptional state, indicating that timing constraints have been violated. We then present centralized and decentralized protocols to implement TAC and a high-level language construct that facilitates its use in distributed real-time programming
A Byzantine Fault Tolerant Distributed Commit Protocol
In this paper, we present a Byzantine fault tolerant distributed commit
protocol for transactions running over untrusted networks. The traditional
two-phase commit protocol is enhanced by replicating the coordinator and by
running a Byzantine agreement algorithm among the coordinator replicas. Our
protocol can tolerate Byzantine faults at the coordinator replicas and a subset
of malicious faults at the participants. A decision certificate, which includes
a set of registration records and a set of votes from participants, is used to
facilitate the coordinator replicas to reach a Byzantine agreement on the
outcome of each transaction. The certificate also limits the ways a faulty
replica can use towards non-atomic termination of transactions, or semantically
incorrect transaction outcomes.Comment: To appear in the proceedings of the 3rd IEEE International Symposium
on Dependable, Autonomic and Secure Computing, 200
Learning Linear Temporal Properties
We present two novel algorithms for learning formulas in Linear Temporal
Logic (LTL) from examples. The first learning algorithm reduces the learning
task to a series of satisfiability problems in propositional Boolean logic and
produces a smallest LTL formula (in terms of the number of subformulas) that is
consistent with the given data. Our second learning algorithm, on the other
hand, combines the SAT-based learning algorithm with classical algorithms for
learning decision trees. The result is a learning algorithm that scales to
real-world scenarios with hundreds of examples, but can no longer guarantee to
produce minimal consistent LTL formulas. We compare both learning algorithms
and demonstrate their performance on a wide range of synthetic benchmarks.
Additionally, we illustrate their usefulness on the task of understanding
executions of a leader election protocol
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