81,327 research outputs found
That’s not my signature! Fail-stop signatures for a post-quantum world
The Snowden\u27s revelations kick-started a community-wide effort to develop cryptographic tools against mass surveillance.
In this work, we propose to add another primitive to that toolbox: Fail-Stop Signatures (FSS) [EC\u2789].
FSS are digital signatures enhanced with a forgery-detection mechanism that can protect a PPT signer from more powerful attackers.
Despite the fascinating concept, research in this area stalled after the \u2790s. However, the ongoing transition to post-quantum cryptography, with its hiccups due to the novelty of underlying assumptions, has become the perfect use case for FSS.
This paper aims to reboot research on FSS with practical use in mind: Our framework for FSS includes ``fine-grained\u27\u27 security definitions (that assume a powerful, but bounded adversary e.g: can break -bit of security, but not -bit).
As an application, we show new FSS constructions for the post-quantum setting.
We show that FSS are equivalent to standard, provably secure digital signatures that do not require rewinding or programming random oracles, and that this implies lattice-based FSS.
Our main construction is an FSS version of SPHINCS, which required building FSS versions of all its building blocks: WOTS, XMSS, and FORS.
In the process, we identify and provide generic solutions for two fundamental issues arising when deriving a large number of private keys from a single seed, and when building FSS for Hash-and-Sign-based signatures
Short One-Time Signatures
We present a new one-time signature scheme having short signatures. Our new scheme supports aggregation, batch verification, and admits efficient proofs of knowledge. It has a fast signing algorithm, requiring only modular additions, and its verification cost is comparable to ECDSA verification. These properties make our scheme suitable for applications on resource-constrained devices such as smart cards and sensor nodes. Along the way, we give a unified description of five previous one-time signature schemes and improve parameter selection for these schemes, and as a corollary we give a fail-stop signature scheme with short signatures
Supersymmetry Without Prejudice at the LHC
The discovery and exploration of Supersymmetry in a model-independent fashion
will be a daunting task due to the large number of soft-breaking parameters in
the MSSM. In this paper, we explore the capability of the ATLAS detector at the
LHC ( TeV, 1 fb) to find SUSY within the 19-dimensional
pMSSM subspace of the MSSM using their standard transverse missing energy and
long-lived particle searches that were essentially designed for mSUGRA. To this
end, we employ a set of k previously generated model points in the
19-dimensional parameter space that satisfy all of the existing experimental
and theoretical constraints. Employing ATLAS-generated SM backgrounds and
following their approach in each of 11 missing energy analyses as closely as
possible, we explore all of these k model points for a possible SUSY
signal. To test our analysis procedure, we first verify that we faithfully
reproduce the published ATLAS results for the signal distributions for their
benchmark mSUGRA model points. We then show that, requiring all sparticle
masses to lie below 1(3) TeV, almost all(two-thirds) of the pMSSM model points
are discovered with a significance in at least one of these 11 analyses
assuming a 50\% systematic error on the SM background. If this systematic error
can be reduced to only 20\% then this parameter space coverage is increased.
These results are indicative that the ATLAS SUSY search strategy is robust
under a broad class of Supersymmetric models. We then explore in detail the
properties of the kinematically accessible model points which remain
unobservable by these search analyses in order to ascertain problematic cases
which may arise in general SUSY searches.Comment: 69 pages, 40 figures, Discussion adde
Toward Full LHC Coverage of Natural Supersymmetry
We argue that combining just a handful of searches for new physics at Run I
of the LHC is sufficient to exclude most supersymmetric extensions of the
Standard Model in which the gluino is kinematically accessible and the spectrum
is natural. Such models typically give rise to significant MET, top quarks
and/or high object multiplicity, and we show that having even one of these
signatures generally results in stringent limits. We also identify, among
models that lack these signatures, the few gaps in coverage remaining, and
propose search strategies to close these gaps. Our results are general and
independent of the details of the spectrum, assumptions about minimality,
R-parity, etc. Our analysis strategy should remain applicable when the LHC
moves to higher energy. Central to our argument are ATLAS and CMS searches for
many jets and low MET, a proposed lepton + many jets search, an ATLAS search
for 6-7 high-pT jets, and a reexamination of the control and signal regions of
the CMS black hole search.Comment: 53 pages, 16 figures, journal versio
Beam Loss Monitors at LHC
One of the main functions of the LHC beam loss measurement system is the
protection of equipment against damage caused by impacting particles creating
secondary showers and their energy dissipation in the matter. Reliability
requirements are scaled according to the acceptable consequences and the
frequency of particle impact events on equipment. Increasing reliability often
leads to more complex systems. The downside of complexity is a reduction of
availability; therefore, an optimum has to be found for these conflicting
requirements. A detailed review of selected concepts and solutions for the LHC
system will be given to show approaches used in various parts of the system
from the sensors, signal processing, and software implementations to the
requirements for operation and documentation.Comment: 16 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
Search for Pair Production of Supersymmetric Top Quarks Mimicking Standard Model Top Event Signatures at CDF
We present results of the search for the super-symmetric partner of the top
quark, the stop quark, decaying to a b-quark and chargino with the subsequent
chargino decay into a neutralino, lepton and neutrino. Using the data sample
corresponding to 2.7 inv fb of integrated luminosity, collected with the CDF
Detector of the Tevatron collider, we reconstruct the stop mass of candidate
events and set 95% C. L. upper limits on masses of the stop quark, chargino and
neutralino and the branching ratio of chargino to neutralino+lepton+neutrino.Comment: ICHEP08 poster, Philadelphia, USA, July 2008. 3 pages, LaTeX, 3
figure
Simplified Supersymmetry with Sneutrino LSP at 8 TeV LHC
The current searches of supersymmetry (SUSY) are based on the neutralino
lightest sparticle (LSP). In this article we instead focus on SUSY with
sneutrino LSP. It is well motivated in many contexts, especially in which
sneutrino services as a dark matter candidate. We first develop a simplified
model, which contains the stop, chagino/neutralino and sneutrino, to describe
the LHC phenomenologies of a large class of models with sneutrino LSP. Then we
investigate bounds on the model using the SUSY searches at the 8 TeV LHC.
Strong exclusion limits are derived, e.g., masses of stop and chargino can be
excluded up to about 900 GeV and 550 GeV, respectively. We also propose
optimizations for some searches without turning to higher energy and
luminosity.Comment: 26 pages, 8 figures,Minor corrections,References adde
An Improved Algorithm for Generating Database Transactions from Relational Algebra Specifications
Alloy is a lightweight modeling formalism based on relational algebra. In
prior work with Fisler, Giannakopoulos, Krishnamurthi, and Yoo, we have
presented a tool, Alchemy, that compiles Alloy specifications into
implementations that execute against persistent databases. The foundation of
Alchemy is an algorithm for rewriting relational algebra formulas into code for
database transactions. In this paper we report on recent progress in improving
the robustness and efficiency of this transformation
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