720 research outputs found
Multi-hop Byzantine reliable broadcast with honest dealer made practical
We revisit Byzantine tolerant reliable broadcast with honest dealer algorithms in multi-hop networks. To tolerate Byzantine faulty nodes arbitrarily spread over the network, previous solutions require a factorial number of messages to be sent over the network if the messages are not authenticated (e.g., digital signatures are not available). We propose modifications that preserve the safety and liveness properties of the original unauthenticated protocols, while highly decreasing their observed message complexity when simulated on several classes of graph topologies, potentially opening to their employment
B-CoC: A Blockchain-Based Chain of Custody for Evidences Management in Digital Forensics
One of the main issues in digital forensics is the management of evidences. From the time of evidence collection until the time of their exploitation in a legal court, evidences may be accessed by multiple parties involved in the investigation that take temporary their ownership. This process, called Chain of Custody (CoC), must ensure that evidences are not altered during the investigation, despite multiple entities owned them, in order to be admissible in a legal court. Currently digital evidences CoC is managed entirely manually with entities involved in the chain required to fill in documents accompanying the evidence. In this paper, we propose a Blockchain-based Chain of Custody (B-CoC) to dematerialize the CoC process guaranteeing auditable integrity of the collected evidences and traceability of owners. We developed a prototype of B-CoC based on Ethereum and we evaluated its performance
Tight Mobile Byzantine Tolerant Atomic Storage
This paper proposes the first implementation of an atomic storage tolerant to
mobile Byzantine agents. Our implementation is designed for the round-based
synchronous model where the set of Byzantine nodes changes from round to round.
In this model we explore the feasibility of multi-writer multi-reader atomic
register prone to various mobile Byzantine behaviors. We prove upper and lower
bounds for solving the atomic storage in all the explored models. Our results,
significantly different from the static case, advocate for a deeper study of
the main building blocks of distributed computing while the system is prone to
mobile Byzantine failures
Stabilizing Server-Based Storage in Byzantine Asynchronous Message-Passing Systems
A stabilizing Byzantine single-writer single-reader (SWSR) regular register,
which stabilizes after the first invoked write operation, is first presented.
Then, new/old ordering inversions are eliminated by the use of a (bounded)
sequence number for writes, obtaining a practically stabilizing SWSR atomic
register. A practically stabilizing Byzantine single-writer multi-reader (SWMR)
atomic register is then obtained by using several copies of SWSR atomic
registers. Finally, bounded time-stamps, with a time-stamp per writer, together
with SWMR atomic registers, are used to construct a practically stabilizing
Byzantine multi-writer multi-reader (MWMR) atomic register. In a system of
servers implementing an atomic register, and in addition to transient failures,
the constructions tolerate t<n/8 Byzantine servers if communication is
asynchronous, and t<n/3 Byzantine servers if it is synchronous. The noteworthy
feature of the proposed algorithms is that (to our knowledge) these are the
first that build an atomic read/write storage on top of asynchronous servers
prone to transient failures, and where up to t of them can be Byzantine
Building Regular Registers with Rational Malicious Servers and Anonymous Clients
The paper addresses the problem of emulating a regular register in a synchronous distributed system where clients invoking and operations are anonymous while server processes maintaining the state of the register may be compromised by rational adversaries (i.e., a server might behave as rational malicious Byzantine process). We first model our problem as a Bayesian game between a client and a rational malicious server where the equilibrium depends on the decisions of the malicious server (behave correctly and not be detected by clients vs returning a wrong register value to clients with the risk of being detected and then excluded by the computation). We prove such equilibrium exists and finally we design a protocol implementing the regular register that forces the rational malicious server to behave correctly
Building an Emulation Environment for Cyber Security Analyses of Complex Networked Systems
Computer networks are undergoing a phenomenal growth, driven by the rapidly
increasing number of nodes constituting the networks. At the same time, the
number of security threats on Internet and intranet networks is constantly
growing, and the testing and experimentation of cyber defense solutions
requires the availability of separate, test environments that best emulate the
complexity of a real system. Such environments support the deployment and
monitoring of complex mission-driven network scenarios, thus enabling the study
of cyber defense strategies under real and controllable traffic and attack
scenarios. In this paper, we propose a methodology that makes use of a
combination of techniques of network and security assessment, and the use of
cloud technologies to build an emulation environment with adjustable degree of
affinity with respect to actual reference networks or planned systems. As a
byproduct, starting from a specific study case, we collected a dataset
consisting of complete network traces comprising benign and malicious traffic,
which is feature-rich and publicly available
Multi-hop Byzantine Reliable Broadcast with Honest Dealer Made Practical
We revisit Byzantine tolerant reliable broadcast with honest dealer algorithms in multi-hop networks. To tolerate Byzantine faulty nodes arbitrarily spread over the network, previous solutions require a factorial number of messages to be sent over the network if the messages are not authenticated (e.g. digital signatures are not available). We propose modifications that preserve the safety and liveness properties of the original unauthenticated protocols, while highly decreasing their observed message complexity when simulated on several classes of graph topologies, potentially opening to their employment
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