71 research outputs found
I2PA, U-prove, and Idemix: An Evaluation of Memory Usage and Computing Time Efficiency in an IoT Context
The Internet of Things (IoT), in spite of its innumerable advantages, brings
many challenges namely issues about users' privacy preservation and constraints
about lightweight cryptography. Lightweight cryptography is of capital
importance since IoT devices are qualified to be resource-constrained. To
address these challenges, several Attribute-Based Credentials (ABC) schemes
have been designed including I2PA, U-prove, and Idemix. Even though these
schemes have very strong cryptographic bases, their performance in
resource-constrained devices is a question that deserves special attention.
This paper aims to conduct a performance evaluation of these schemes on
issuance and verification protocols regarding memory usage and computing time.
Recorded results show that both I2PA and U-prove present very interesting
results regarding memory usage and computing time while Idemix presents very
low performance with regard to computing time
Universal Isgur-Wise form factors from QCD sum rules in HQET
We review the role of the universal Isgur-Wise functions parameterizing the
meson semileptonic matrix elements to charm states in the infinite heavy
quark mass limit. We also discuss the determination of one of such form factors
by QCD sum rules in the framework of the Heavy Quark Effective Theory.Comment: LaTex, 5 pages, 3 figures. Talk given at International Euroconference
on Quantum Chromodynamics (QCD98), Montpellier, France, 2 - 8 Jul 199
Assessment of attribute-based credentials for privacy-preserving road traffic services in smart cities
Smart cities involve the provision of advanced services for road traffic users. Vehicular ad hoc networks (VANETs) are a promising communication technology in this regard. Preservation of privacy is crucial in these services to foster their acceptance. Previous approaches have mainly focused on PKI-based or ID-based cryptography. However, these works have not fully addressed the minimum information disclosure principle. Thus, questions such as how to prove that a driver is a neighbour of a given zone, without actually disclosing his identity or real address, remain unaddressed. A set of techniques, referred to as Attribute-Based Credentials (ABCs), have been proposed to address this need in traditional computation scenarios. In this paper, we explore the use of ABCs in the vehicular context. For this purpose, we focus on a set of use cases from European Telecommunications Standards Institute (ETSI) Basic Set of Applications, specially appropriate for the early development of smart cities. We assess which ABC techniques are suitable for this scenario, focusing on three representative ones—Idemix, U-Prove and VANET-updated Persiano systems. Our experimental results show that they are feasible in VANETs considering state-of-the-art technologies, and that Idemix is the most promising technique for most of the considered use cases.This work was supported by the MINECO grant TIN2013-46469-R (SPINY: Security and Privacy in the Internet of You); the CAM grant S2013/ICE-3095 (CIBERDINE: Cybersecurity, Data, and Risks) and by the MINECO grant TIN2016-79095-C2-2-R (SMOG-DEV - Security mechanisms for fog computing: advanced security for devices). Jose Maria de Fuentes and Lorena Gonzalez were also supported by the Programa de Ayudas para la Movilidad of Carlos III University of Madrid
The anomalous threshold, confinement, and an essential singularity in the heavy-light form factor
The analytic behavior of the heavy-light meson form factor is investigated
using several relativistic examples including unconfined, weakly confined, and
strongly confined mesons. It is observed that confinement erases the anomalous
threshold singularity and also induces an essential singularity at the normal
annihilation threshold. In the weak confinement limit, the "would be" anomalous
threshold contribution is identical to that of the real singularity on its
space-like side.Comment: Latex 2.09 with epsf.sty. 24 pages of text and 8 postscript figures.
Postscript version of complete paper will also be available soon at
http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-983 or at
ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-98
On the validity of the reduced Salpeter equation
We adapt a general method to solve both the full and reduced Salpeter
equations and systematically explore the conditions under which these two
equations give equivalent results in meson dynamics. The effects of constituent
mass, angular momentum state, type of interaction, and the nature of
confinement are all considered in an effort to clearly delineate the range of
validity of the reduced Salpeter approximations. We find that for
the solutions are strikingly similar for all
constituent masses. For zero angular momentum states the full and reduced
Salpeter equations give different results for small quark mass especially with
a large additive constant coordinate space potential. We also show that
corrections to heavy-light energy levels can be accurately
computed with the reduced equation.Comment: Latex (uses epsf macro), 24 pages of text, 12 postscript figures
included. Slightly revised version, to appear in Phys. Rev.
Decay constants of P and D-wave heavy-light mesons
We investigate decay constants of P and D-wave heavy-light mesons within the
mock-meson approach. Numerical estimates are obtained using the relativistic
quark model. We also comment on recent calculations of heavy-light
pseudo-scalar and vector decay constants.Comment: REVTeX, 22 pages, uses epsf macro, 8 postscript figures include
Semileptonic B decays into excited charmed mesons from QCD sum rules
Exclusive semileptonic decays into excited charmed mesons are studied
with QCD sum rules in the leading order of heavy quark effective theory. Two
universal Isgur-Wise functions \tau and \zeta for semileptonic B decays into
four lowest lying excited mesons (, , , and ) are
determined. The decay rates and branching ratios for these processes are
calculated.Comment: RevTeX, 17 pages including 2 figure
Semi-leptonic B decays into higher charmed resonances
We apply HQET to semi-leptonic meson decays into a variety of excited
charm states. Using three realistic meson models with fermionic light degrees
of freedom, we examine the extent that the sum of exclusive single charmed
states account for the inclusive semi-leptonic decay rate. The consistency
of form factors with the Bjorken and Voloshin sum rules is also investigated.Comment: Latex, 27 pages. A few references and errors corrected, to appear in
Phys. Rev.
Potential Models for Radiative Rare B Decays
We compute the branching ratios for the radiative rare decays of B into
K-Meson states and compare them to the experimentally determined branching
ratio for inclusive decay b -> s gamma using non relativistic quark model, and
form factor definitions consistent with HQET covariant trace formalism. Such
calculations necessarily involve a potential model. In order to test the
sensitivity of calculations to potential models we have used three different
potentials, namely linear potential, screening confining potential and heavy
quark potential as it stands in QCD.We find the branching ratios relative to
the inclusive b ->s gamma decay to be (16.07\pm 5.2)% for B -> K^* (892)gamma
and (7.25\pm 3.2)% for B -> K_2^* (1430)gamma for linear potential. In the case
of the screening confining potential these values are (19.75\pm 5.3)% and
(4.74\pm 1.2)% while those for the heavy quark potential are (11.18\pm 4.6)%
and (5.09\pm 2.7)% respectively. All these values are consistent with the
corresponding present CLEO experimental values: (16.25\pm 1.21)% and (5.93\pm
0.46)%.Comment: RevTeX, 6 pages, 1 eps figur
Semileptonic B decays to excited charmed mesons
Exclusive semileptonic B decays into excited charmed mesons are investigated
at order in the heavy quark effective theory. Differential
decay rates for each helicity state of the four lightest excited mesons
(, , , and ) are examined. At zero recoil,
corrections to the matrix elements of the weak currents can
be written in terms of the leading Isgur-Wise functions for the corresponding
transition and meson mass splittings. A model independent prediction is found
for the slope parameter of the decay rate into helicity zero at zero
recoil. The differential decay rates are predicted, including
corrections with some model dependence away from zero
recoil and including order corrections. Ratios of various exclusive
branching ratios are computed. Matrix elements of the weak currents between
mesons and other excited charmed mesons are discussed at zero recoil to order
. These amplitudes vanish at leading order, and can be
written at order in terms of local matrix elements.
Applications to decay sum rules and factorization are presented.Comment: 39 pages revtex including 10 figures, uses epsf. Substantial
improvements throughout the pape
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