963 research outputs found
Lightweight Asynchronous Verifiable Secret Sharing with Optimal Resilience
We present new protocols for *Asynchronous Verifiable Secret Sharing* for Shamir (i.e., threshold ) sharing of secrets.
Our protocols:
* Use only lightweight cryptographic primitives, such as hash functions;
* Can share secrets over rings such as as well as finite fields ;
* Provide *optimal resilience*, in the sense that they tolerate up to corruptions, where is the total number of parties;
* Are *complete*, in the sense that they guarantee that if any honest party receives their share then all honest parties receive their shares;
* Employ *batching* techniques, whereby a dealer shares many secrets in parallel, and achieves an amortized communication complexity that is linear in , at least on the happy path , where no party *provably* misbehaves
Changes in Physiology before, during, and after Yawning
The ultimate function of yawning continues to be debated. Here, we examine physiological measurements taken before, during, and after yawns in humans, in an attempt to identify key proximate mechanisms associated with this behavior. In two separate studies we measured changes in heart rate, lung volume, eye closure, skin conductance, ear pulse, respiratory sinus arrhythmia, and respiratory rate. Data were depicted from 75âs before and after yawns, and analyzed at baseline, during, and immediately following yawns. Increases in heart rate, lung volume, and eye muscle tension were observed during or immediately following yawning. Patterns of physiological changes during yawning were then compared to data from non-yawning deep inhalations. In one study, respiration period increased following the execution of a yawn. Much of the variance in physiology surrounding yawning was specific to the yawning event. This was not the case for deep inhalation. We consider our findings in light of various hypotheses about the function of yawning and conclude that they are most consistent with the brain cooling hypothesis
An efficient quantum algorithm for the hidden subgroup problem in extraspecial groups
Extraspecial groups form a remarkable subclass of p-groups. They are also
present in quantum information theory, in particular in quantum error
correction. We give here a polynomial time quantum algorithm for finding hidden
subgroups in extraspecial groups. Our approach is quite different from the
recent algorithms presented in [17] and [2] for the Heisenberg group, the
extraspecial p-group of size p3 and exponent p. Exploiting certain nice
automorphisms of the extraspecial groups we define specific group actions which
are used to reduce the problem to hidden subgroup instances in abelian groups
that can be dealt with directly.Comment: 10 page
Self-consistent theory of reversible ligand binding to a spherical cell
In this article, we study the kinetics of reversible ligand binding to
receptors on a spherical cell surface using a self-consistent stochastic
theory. Binding, dissociation, diffusion and rebinding of ligands are
incorporated into the theory in a systematic manner. We derive explicitly the
time evolution of the ligand-bound receptor fraction p(t) in various regimes .
Contrary to the commonly accepted view, we find that the well-known
Berg-Purcell scaling for the association rate is modified as a function of
time. Specifically, the effective on-rate changes non-monotonically as a
function of time and equals the intrinsic rate at very early as well as late
times, while being approximately equal to the Berg-Purcell value at
intermediate times. The effective dissociation rate, as it appears in the
binding curve or measured in a dissociation experiment, is strongly modified by
rebinding events and assumes the Berg-Purcell value except at very late times,
where the decay is algebraic and not exponential. In equilibrium, the ligand
concentration everywhere in the solution is the same and equals its spatial
mean, thus ensuring that there is no depletion in the vicinity of the cell.
Implications of our results for binding experiments and numerical simulations
of ligand-receptor systems are also discussed.Comment: 23 pages with 4 figure
Algorithms for zero-dimensional ideals using linear recurrent sequences
Inspired by Faug\`ere and Mou's sparse FGLM algorithm, we show how using
linear recurrent multi-dimensional sequences can allow one to perform
operations such as the primary decomposition of an ideal, by computing the
annihilator of one or several such sequences.Comment: LNCS, Computer Algebra in Scientific Computing CASC 201
Perceptions of Rural Superintendents on Factors Influencing Employment Decisions
School districts struggle to attract and maintain a sufficient supply of highly capable superintendents. High-needs within rural districts, in particular, often are not able to attract and retain effective leaders. The issue of short superintendent tenure has drawn speculation and concern that revolving leadership may have negative consequences for schools and student achievement. A variety of factors contribute to superintendent turnover including: school board relations, job satisfaction, school district characteristics, and the personal characteristics of superintendents (Grissom & Anderson, 2012; Kamrath & Brunner, 2014; Wood, Finch & Mirecki, 2013). This study provides insight into perceptions of rural superintendents (n=10) and why they stay or leave their roles in rural Idaho school districts. As we look for ways to build capacity for leadership and social change in rural settings, it is important to understand factors influencing the stability of leadership from the superintendent role. Findings suggest that school boards remain the most influential factor
A Machine-Checked Formalization of the Generic Model and the Random Oracle Model
Most approaches to the formal analyses of cryptographic protocols make the perfect cryptography assumption, i.e. the hypothese that there is no way to obtain knowledge about the plaintext pertaining to a ciphertext without knowing the key. Ideally, one would prefer to rely on a weaker hypothesis on the computational cost of gaining information about the plaintext pertaining to a ciphertext without knowing the key. Such a view is permitted by the Generic Model and the Random Oracle Model which provide non-standard computational models in which one may reason about the computational cost of breaking a cryptographic scheme. Using the proof assistant Coq, we provide a machine-checked account of the Generic Model and the Random Oracle Mode
Hard Instances of the Constrained Discrete Logarithm Problem
The discrete logarithm problem (DLP) generalizes to the constrained DLP,
where the secret exponent belongs to a set known to the attacker. The
complexity of generic algorithms for solving the constrained DLP depends on the
choice of the set. Motivated by cryptographic applications, we study sets with
succinct representation for which the constrained DLP is hard. We draw on
earlier results due to Erd\"os et al. and Schnorr, develop geometric tools such
as generalized Menelaus' theorem for proving lower bounds on the complexity of
the constrained DLP, and construct sets with succinct representation with
provable non-trivial lower bounds
Group Diffie-Hellman Key Exchange Secure against Dictionary Attacks
Group Diffie-Hellman schemes for password-based key exchange are designed to provide a pool of players communicating over a public network, and sharing just a human-memorable password, with a session key (e.g, the key is used for multicast data integrity and confidentiality) . The fundamental security goal to achieve in this scenario is security against dictionary attacks. While solutions have been proposed to solve this problem no formal treatment has ever been suggested. In this paper, we define a security model and then present a protocol with its security proof in both the random oracle model and the ideal-cipher model
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