24,255 research outputs found
Verifying privacy by little interaction and no process equivalence
While machine-assisted verification of classical security goals such as confidentiality and authentication is
well-established, it is less mature for recent ones. Electronic voting protocols claim properties such as voter
privacy. The most common modelling involves indistinguishability, and is specified via trace equivalence in cryptographic extensions of process calculi. However, it has shown restrictions. We describe a novel model, based on unlinkability between two pieces of information. Specifying it as an extension to the Inductive Method allows us to establish voter privacy without the need for approximation or session bounding. The two
models and their latest specifications are contrasted
Unitarity of black hole evaporation in final-state projection models
Almheiri et al. have emphasized that otherwise reasonable beliefs about black
hole evaporation are incompatible with the monogamy of quantum entanglement, a
general property of quantum mechanics. We investigate the final-state
projection model of black hole evaporation proposed by Horowitz and Maldacena,
pointing out that this model admits cloning of quantum states and polygamous
entanglement, allowing unitarity of the evaporation process to be reconciled
with smoothness of the black hole event horizon. Though the model seems to
require carefully tuned dynamics to ensure exact unitarity of the black hole
S-matrix, for a generic final-state boundary condition the deviations from
unitarity are exponentially small in the black hole entropy; furthermore
observers inside black holes need not detect any deviations from standard
quantum mechanics. Though measurements performed inside old black holes could
potentially produce causality-violating phenomena, the computational complexity
of decoding the Hawking radiation may render the causality violation
unobservable. Final-state projection models illustrate how inviolable
principles of standard quantum mechanics might be circumvented in a theory of
quantum gravity.Comment: (v3) 27 pages, 16 figures. Expanded discussion of measurements inside
black hole
Fraud cycles
Fraud is an ancient crime and one that annually causes hundreds of billions of dollars in losses. We examine the behavioral patterns over time of different types of frauds, which illustrate cyclical frequencies. We develop an evolutionary theory that suggests cyclic behavior in frauds should be common.fraud, cycle, steady state
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