903 research outputs found
Design Professional Liability for Construction Worksite Accidents - How Arkansas Led the way to a National Consensus
Three major developments underlie the law of architect or engineer (a/e) liability to construction workers, beginning in the second half of the twentieth century: (1) a change from a no-duty regime to a duty of care under a foreseeability test, (2) reactions to that expanded liability by changes to standard form documents by industry associations (in particular the American Institute of Architects (AIA)), (3) currently culminating in a broad national consensus. The Arkansas Supreme Court was instrumental in framing the issues of this jurisprudence early in its development and later contributed to its continued evolution
To mesh or not to mesh: flexible wireless indoor communication among mobile robots in industrial environments
Mobile robots such as automated guided vehicles become increasingly important in industry as they can greatly increase efficiency. For their operation such robots must rely on wireless communication, typically realized by connecting them to an existing enterprise network. In this paper we motivate that such an approach is not always economically viable or might result in performance issues. Therefore we propose a flexible and configurable mixed architecture that leverages on mesh capabilities whenever appropriate. Through experiments on a wireless testbed for a variety of scenarios, we analyse the impact of roaming, mobility and traffic separation and demonstrate the potential of our approach
The ping-pong protocol can be attacked without eavesdropping
Attack the ping-pong protocol without eavesdropping.Comment: PACS: 03.67.H
Teleportation: from probability distributions to quantum states
The role of the off-diagonal density matrix elements of the entangled pair is
investigated in quantum teleportation of a qbit. The dependence between them
and the off-diagonal elements of the teleported density matrix is shown to be
linear. In this way the ideal quantum teleportation is related to an entirely
classical communication protocol: the one-time pad cypher. The latter can be
regarded as the classical counterpart of Bennett's quantum teleportation
scheme. The quantum-to-classical transition is demonstrated on the statistics
of a gedankenexperiment.Comment: 11 pages, 1 figure, accepted for publication in J. Phys. A (Math.
Gen.
Breaking a chaos-noise-based secure communication scheme
This paper studies the security of a secure communication scheme based on two
discrete-time intermittently-chaotic systems synchronized via a common random
driving signal. Some security defects of the scheme are revealed: 1) the key
space can be remarkably reduced; 2) the decryption is insensitive to the
mismatch of the secret key; 3) the key-generation process is insecure against
known/chosen-plaintext attacks. The first two defects mean that the scheme is
not secure enough against brute-force attacks, and the third one means that an
attacker can easily break the cryptosystem by approximately estimating the
secret key once he has a chance to access a fragment of the generated
keystream. Yet it remains to be clarified if intermittent chaos could be used
for designing secure chaotic cryptosystems.Comment: RevTeX4, 11 pages, 15 figure
Single Qubit Quantum Secret Sharing
We present a simple and practical protocol for the solution of a secure
multiparty communication task, the secret sharing, and its experimental
realization. In this protocol, a secret message is split among several parties
in a way that its reconstruction require the collaboration of the participating
parties. In the proposed scheme the parties solve the problem by a sequential
communication of a single qubit. Moreover we show that our scheme is equivalent
to the use of a multiparty entangled GHZ state but easier to realize and better
scalable in practical applications.Comment: 5 pages, 2 figures, submitted December 29, 200
Quantum secret sharing with qudit graph states
We present a unified formalism for threshold quantum secret sharing using
graph states of systems with prime dimension. We construct protocols for three
varieties of secret sharing: with classical and quantum secrets shared between
parties over both classical and quantum channels.Comment: 13 pages, 12 figures. v2: Corrected to reflect imperfections of (n,n)
QQ protocol. Also changed notation from to , corrected typos,
updated references, shortened introduction. v3: Updated acknowledgement
Detecting brute-force attacks on cryptocurrency wallets
Blockchain is a distributed ledger, which is protected against malicious
modifications by means of cryptographic tools, e.g. digital signatures and hash
functions. One of the most prominent applications of blockchains is
cryptocurrencies, such as Bitcoin. In this work, we consider a particular
attack on wallets for collecting assets in a cryptocurrency network based on
brute-force search attacks. Using Bitcoin as an example, we demonstrate that if
the attack is implemented successfully, a legitimate user is able to prove that
fact of this attack with a high probability. We also consider two options for
modification of existing cryptocurrency protocols for dealing with this type of
attacks. First, we discuss a modification that requires introducing changes in
the Bitcoin protocol and allows diminishing the motivation to attack wallets.
Second, an alternative option is the construction of special smart-contracts,
which reward the users for providing evidence of the brute-force attack. The
execution of this smart-contract can work as an automatic alarm that the
employed cryptographic mechanisms, and (particularly) hash functions, have an
evident vulnerability.Comment: 10 pages, 2 figures; published versio
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