17,739 research outputs found
Distributed Relay Protocol for Probabilistic Information-Theoretic Security in a Randomly-Compromised Network
We introduce a simple, practical approach with probabilistic
information-theoretic security to mitigate one of quantum key distribution's
major limitations: the short maximum transmission distance (~200 km) possible
with present day technology. Our scheme uses classical secret sharing
techniques to allow secure transmission over long distances through a network
containing randomly-distributed compromised nodes. The protocol provides
arbitrarily high confidence in the security of the protocol, with modest
scaling of resource costs with improvement of the security parameter. Although
some types of failure are undetectable, users can take preemptive measures to
make the probability of such failures arbitrarily small.Comment: 12 pages, 2 figures; added proof of verification sub-protocol, minor
correction
Resilient Network Coding in the Presence of Byzantine Adversaries
Network coding substantially increases network throughput. But since it involves mixing of information inside the network, a single corrupted packet generated by a malicious node can end up contaminating all the information reaching a
destination, preventing decoding.
This paper introduces distributed polynomial-time rate-optimal network codes that work in the presence of Byzantine nodes. We present algorithms that target adversaries with different attacking capabilities. When the adversary can eavesdrop on all links and jam zO links, our first algorithm achieves a rate of C - 2zO, where C is the network capacity. In contrast, when the adversary has limited eavesdropping capabilities, we provide algorithms that achieve the higher rate of C - zO.
Our algorithms attain the optimal rate given the strength of the adversary. They are information-theoretically secure. They operate in a distributed manner, assume no knowledge of the topology, and can be designed and implemented in polynomial time. Furthermore, only the source and destination need to be modified; nonmalicious nodes inside the network are oblivious to the presence of adversaries and implement a classical distributed network code. Finally, our algorithms work over wired and wireless networks
LightChain: A DHT-based Blockchain for Resource Constrained Environments
As an append-only distributed database, blockchain is utilized in a vast
variety of applications including the cryptocurrency and Internet-of-Things
(IoT). The existing blockchain solutions have downsides in communication and
storage efficiency, convergence to centralization, and consistency problems. In
this paper, we propose LightChain, which is the first blockchain architecture
that operates over a Distributed Hash Table (DHT) of participating peers.
LightChain is a permissionless blockchain that provides addressable blocks and
transactions within the network, which makes them efficiently accessible by all
the peers. Each block and transaction is replicated within the DHT of peers and
is retrieved in an on-demand manner. Hence, peers in LightChain are not
required to retrieve or keep the entire blockchain. LightChain is fair as all
of the participating peers have a uniform chance of being involved in the
consensus regardless of their influence such as hashing power or stake.
LightChain provides a deterministic fork-resolving strategy as well as a
blacklisting mechanism, and it is secure against colluding adversarial peers
attacking the availability and integrity of the system. We provide mathematical
analysis and experimental results on scenarios involving 10K nodes to
demonstrate the security and fairness of LightChain. As we experimentally show
in this paper, compared to the mainstream blockchains like Bitcoin and
Ethereum, LightChain requires around 66 times less per node storage, and is
around 380 times faster on bootstrapping a new node to the system, while each
LightChain node is rewarded equally likely for participating in the protocol
Maximizing Algebraic Connectivity of Constrained Graphs in Adversarial Environments
This paper aims to maximize algebraic connectivity of networks via topology
design under the presence of constraints and an adversary. We are concerned
with three problems. First, we formulate the concave maximization topology
design problem of adding edges to an initial graph, which introduces a
nonconvex binary decision variable, in addition to subjugation to general
convex constraints on the feasible edge set. Unlike previous methods, our
method is justifiably not greedy and capable of accommodating these additional
constraints. We also study a scenario in which a coordinator must selectively
protect edges of the network from a chance of failure due to a physical
disturbance or adversarial attack. The coordinator needs to strategically
respond to the adversary's action without presupposed knowledge of the
adversary's feasible attack actions. We propose three heuristic algorithms for
the coordinator to accomplish the objective and identify worst-case preventive
solutions. Each algorithm is shown to be effective in simulation and we provide
some discussion on their compared performance.Comment: 8 pages, submitted to European Control Conference 201
Deconstructing the Blockchain to Approach Physical Limits
Transaction throughput, confirmation latency and confirmation reliability are
fundamental performance measures of any blockchain system in addition to its
security. In a decentralized setting, these measures are limited by two
underlying physical network attributes: communication capacity and
speed-of-light propagation delay. Existing systems operate far away from these
physical limits. In this work we introduce Prism, a new proof-of-work
blockchain protocol, which can achieve 1) security against up to 50%
adversarial hashing power; 2) optimal throughput up to the capacity C of the
network; 3) confirmation latency for honest transactions proportional to the
propagation delay D, with confirmation error probability exponentially small in
CD ; 4) eventual total ordering of all transactions. Our approach to the design
of this protocol is based on deconstructing the blockchain into its basic
functionalities and systematically scaling up these functionalities to approach
their physical limits.Comment: Computer and Communications Security, 201
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