262 research outputs found
Lesbian and bisexual women's experiences of sexuality-based discrimination and their appearance concerns
Lesbian and bisexual women frequently experience sexuality-based discrimination, which is often based on others' judgements about their appearance. This short article aims to explore whether there is a relationship between lesbian and bisexual women's experiences of sexuality-based discrimination and their satisfaction with the way that they look. Findings from an online survey suggest that discrimination is negatively related to appearance satisfaction for lesbian women, but not for bisexual women. It is argued that this difference exists because lesbian appearance norms are more recognisable and distinctive than bisexual women's appearance norms
Public-Coin Zero-Knowledge Arguments with (almost) Minimal Time and Space Overheads
Zero-knowledge protocols enable the truth of a mathematical statement to be certified by a verifier without revealing any other information. Such protocols are a cornerstone of modern cryptography and recently are becoming more and more practical. However, a major bottleneck in deployment is the efficiency of the prover and, in particular, the space-efficiency of the protocol.
For every relation that can be verified in time and space , we construct a public-coin zero-knowledge argument in which the prover runs in time and space . Our proofs have length and the verifier runs in time (and space ). Our scheme is in the random oracle model and relies on the hardness of discrete log in prime-order groups.
Our main technical contribution is a new space efficient polynomial commitment scheme for multi-linear polynomials. Recall that in such a scheme, a sender commits to a given multi-linear polynomial so that later on it can prove to a receiver statements of the form . In our scheme, which builds on the commitment schemes of Bootle et al. (Eurocrypt 2016) and Bünz et al. (S&P 2018), we assume that the sender is given multi-pass streaming access to the evaluations of on the Boolean hypercube and w show how to implement both the sender and receiver in roughly time and space and with communication complexity roughly
Quantum homomorphic encryption for circuits of low -gate complexity
Fully homomorphic encryption is an encryption method with the property that
any computation on the plaintext can be performed by a party having access to
the ciphertext only. Here, we formally define and give schemes for quantum
homomorphic encryption, which is the encryption of quantum information such
that quantum computations can be performed given the ciphertext only. Our
schemes allows for arbitrary Clifford group gates, but become inefficient for
circuits with large complexity, measured in terms of the non-Clifford portion
of the circuit (we use the "" non-Clifford group gate, which is also
known as the -gate).
More specifically, two schemes are proposed: the first scheme has a
decryption procedure whose complexity scales with the square of the number of
-gates (compared with a trivial scheme in which the complexity scales with
the total number of gates); the second scheme uses a quantum evaluation key of
length given by a polynomial of degree exponential in the circuit's -gate
depth, yielding a homomorphic scheme for quantum circuits with constant
-depth. Both schemes build on a classical fully homomorphic encryption
scheme.
A further contribution of ours is to formally define the security of
encryption schemes for quantum messages: we define quantum indistinguishability
under chosen plaintext attacks in both the public and private-key settings. In
this context, we show the equivalence of several definitions.
Our schemes are the first of their kind that are secure under modern
cryptographic definitions, and can be seen as a quantum analogue of classical
results establishing homomorphic encryption for circuits with a limited number
of multiplication gates. Historically, such results appeared as precursors to
the breakthrough result establishing classical fully homomorphic encryption
Simple Schemes in the Bounded Storage Model
The bounded storage model promises unconditional security
proofs against computationally unbounded adversaries, so long as the
adversary’s space is bounded. In this work, we develop simple new constructions
of two-party key agreement, bit commitment, and oblivious
transfer in this model. In addition to simplicity, our constructions have
several advantages over prior work, including an improved number of
rounds and enhanced correctness. Our schemes are based on Raz’s lower
bound for learning parities
Asexuality: Classification and characterization
This is a post-print version of the article. The official published version can be obtaineed at the link below.The term “asexual” has been defined in many different ways and asexuality has received very little research attention. In a small qualitative study (N = 4), individuals who self-identified as asexual were interviewed to help formulate hypotheses for a larger study. The second larger study was an online survey drawn from a convenience sample designed to better characterize asexuality and to test predictors of asexual identity. A convenience sample of 1,146 individuals (N = 41 self-identified asexual) completed online questionnaires assessing sexual history, sexual inhibition and excitation, sexual desire, and an open-response questionnaire concerning asexual identity. Asexuals reported significantly less desire for sex with a partner, lower sexual arousability, and lower sexual excitation but did not differ consistently from non-asexuals in their sexual inhibition scores or their desire to masturbate. Content analyses supported the idea that low sexual desire is the primary feature predicting asexual identity
Bounded-Collusion IBE from Key Homomorphism
In this work, we show how to construct IBE schemes that are secure against a bounded number of collusions, starting with underlying PKE schemes which possess linear homomorphisms over their keys. In particular, this enables us to exhibit a new (bounded-collusion) IBE construction based on the quadratic residuosity assumption, without any need to assume the existence of random oracles. The new IBE’s public parameters are of size O(tλlogI) where I is the total number of identities which can be supported by the system, t is the number of collusions which the system is secure against, and λ is a security parameter. While the number of collusions is bounded, we note that an exponential number of total identities can be supported.
More generally, we give a transformation that takes any PKE satisfying Linear Key Homomorphism, Identity Map Compatibility, and the Linear Hash Proof Property and translates it into an IBE secure against bounded collusions. We demonstrate that these properties are more general than our quadratic residuosity-based scheme by showing how a simple PKE based on the DDH assumption also satisfies these properties.National Science Foundation (U.S.) (NSF CCF-0729011)National Science Foundation (U.S.) (NSF CCF-1018064)United States. Defense Advanced Research Projects Agency (DARPA FA8750-11-2-0225
Greatest Fixed Points of Probabilistic Min/Max Polynomial Equations, and Reachability for Branching Markov Decision Processes?
We give polynomial time algorithms for quantitative (and qualitative)
reachability analysis for Branching Markov Decision Processes (BMDPs).
Specifically, given a BMDP, and given an initial population, where the
objective of the controller is to maximize (or minimize) the probability of
eventually reaching a population that contains an object of a desired (or
undesired) type, we give algorithms for approximating the supremum (infimum)
reachability probability, within desired precision epsilon > 0, in time
polynomial in the encoding size of the BMDP and in log(1/epsilon). We
furthermore give P-time algorithms for computing epsilon-optimal strategies for
both maximization and minimization of reachability probabilities. We also give
P-time algorithms for all associated qualitative analysis problems, namely:
deciding whether the optimal (supremum or infimum) reachability probabilities
are 0 or 1. Prior to this paper, approximation of optimal reachability
probabilities for BMDPs was not even known to be decidable.
Our algorithms exploit the following basic fact: we show that for any BMDP,
its maximum (minimum) non-reachability probabilities are given by the greatest
fixed point (GFP) solution g* in [0,1]^n of a corresponding monotone max (min)
Probabilistic Polynomial System of equations (max/min-PPS), x=P(x), which are
the Bellman optimality equations for a BMDP with non-reachability objectives.
We show how to compute the GFP of max/min PPSs to desired precision in P-time.
We also study more general Branching Simple Stochastic Games (BSSGs) with
(non-)reachability objectives. We show that: (1) the value of these games is
captured by the GFP of a corresponding max-minPPS; (2) the quantitative problem
of approximating the value is in TFNP; and (3) the qualitative problems
associated with the value are all solvable in P-time
Coordination in multiagent systems and Laplacian spectra of digraphs
Constructing and studying distributed control systems requires the analysis
of the Laplacian spectra and the forest structure of directed graphs. In this
paper, we present some basic results of this analysis partially obtained by the
present authors. We also discuss the application of these results to
decentralized control and touch upon some problems of spectral graph theory.Comment: 15 pages, 2 figures, 40 references. To appear in Automation and
Remote Control, Vol.70, No.3, 200
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