10,943 research outputs found
Towards Stabilization of Distributed Systems under Denial-of-Service
In this paper, we consider networked distributed systems in the presence of
Denial-of-Service (DoS) attacks, namely attacks that prevent transmissions over
the communication network. First, we consider a simple and typical scenario
where communication sequence is purely Round-robin and we explicitly calculate
a bound of attack frequency and duration, under which the interconnected
large-scale system is asymptotically stable. Second, trading-off system
resilience and communication load, we design a hybrid transmission strategy
consisting of Zeno-free distributed event-triggered control and Round-robin. We
show that with lower communication loads, the hybrid communication strategy
enables the systems to have the same resilience as in pure Round-robin
Octopus: A Secure and Anonymous DHT Lookup
Distributed Hash Table (DHT) lookup is a core technique in structured
peer-to-peer (P2P) networks. Its decentralized nature introduces security and
privacy vulnerabilities for applications built on top of them; we thus set out
to design a lookup mechanism achieving both security and anonymity, heretofore
an open problem. We present Octopus, a novel DHT lookup which provides strong
guarantees for both security and anonymity. Octopus uses attacker
identification mechanisms to discover and remove malicious nodes, severely
limiting an adversary's ability to carry out active attacks, and splits lookup
queries over separate anonymous paths and introduces dummy queries to achieve
high levels of anonymity. We analyze the security of Octopus by developing an
event-based simulator to show that the attacker discovery mechanisms can
rapidly identify malicious nodes with low error rate. We calculate the
anonymity of Octopus using probabilistic modeling and show that Octopus can
achieve near-optimal anonymity. We evaluate Octopus's efficiency on Planetlab
with 207 nodes and show that Octopus has reasonable lookup latency and
manageable communication overhead
Control over adversarial packet-dropping communication networks revisited
We revisit a one-step control problem over an adversarial packet-dropping
link. The link is modeled as a set of binary channels controlled by a strategic
jammer whose intention is to wage a `denial of service' attack on the plant by
choosing a most damaging channel-switching strategy. The paper introduces a
class of zero-sum games between the jammer and controller as a scenario for
such attack, and derives necessary and sufficient conditions for these games to
have a nontrivial saddle-point equilibrium. At this equilibrium, the jammer's
optimal policy is to randomize in a region of the plant's state space, thus
requiring the controller to undertake a nontrivial response which is different
from what one would expect in a standard stochastic control problem over a
packet dropping channel.Comment: This paper has been accepted for presentation at the 2014 American
Control Conference, Portland, Orego
Questions related to Bitcoin and other Informational Money
A collection of questions about Bitcoin and its hypothetical relatives
Bitguilder and Bitpenny is formulated. These questions concern technical issues
about protocols, security issues, issues about the formalizations of
informational monies in various contexts, and issues about forms of use and
misuse. Some questions are formulated in the more general setting of
informational monies and near-monies.
We also formulate questions about legal, psychological, and ethical aspects
of informational money. Finally we formulate a number of questions concerning
the economical merits of and outlooks for Bitcoin.Comment: 31 pages. In v2 the section on patterns for use and misuse has been
improved and expanded with so-called contaminations. Other small improvements
were made and 13 additional references have been include
Resilient Control Under Denial-of-Service:Results and Research Directions
The question of security is becoming central for the current generation of engineering systems which more and more rely on networks to support monitoring and control tasks. This chapter addresses the question of designing network control systems that are resilient to Denial-of-Service, that is to phenomena which render a communication network unavailable to use. We review recent results in this area and discuss some of the research challenges.</p
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