14,942 research outputs found
X.509 certificate error testing
X.509 Certificates are used by a wide range of technologies to verify identities, while the SSL protocol is used to provide a secure encrypted tunnel through which data can be sent over a public network. Combined both of these technologies provides the basis of the public key infrastructure (PKI). While the concept of PKI is a good idea, the different implementation of the technologies in different operating system and clients often lead to weaknesses. This paper proposes a methodology to automate the testing of SSL clients by generating both bogus and malformed certificates in order to evaluate the client’s response and identify potential threats to network infrastructures
Encoding algebraic power series
Algebraic power series are formal power series which satisfy a univariate
polynomial equation over the polynomial ring in n variables. This relation
determines the series only up to conjugacy. Via the Artin-Mazur theorem and the
implicit function theorem it is possible to describe algebraic series
completely by a vector of polynomials in n+p variables. This vector will be the
code of the series. In the paper, it is then shown how to manipulate algebraic
series through their code. In particular, the Weierstrass division and the
Grauert-Hironaka-Galligo division will be performed on the level of codes, thus
providing a finite algorithm to compute the quotients and the remainder of the
division.Comment: 35 page
Viability of vector-tensor theories of gravity
We present a detailed study of the viability of general vector-tensor
theories of gravity in the presence of an arbitrary temporal background vector
field. We find that there are six different classes of theories which are
indistinguishable from General Relativity by means of local gravity
experiments. We study the propagation speeds of scalar, vector and tensor
perturbations and obtain the conditions for classical stability of those
models. We compute the energy density of the different modes and find the
conditions for the absence of ghosts in the quantum theory. We conclude that
the only theories which can pass all the viability conditions for arbitrary
values of the background vector field are not only those of the pure Maxwell
type, but also Maxwell theories supplemented with a (Lorentz type) gauge fixing
term.Comment: 13 pages, 2 figures, 1 table. Final version to appear in JCA
Photo-desorption of H2O:CO:NH3 circumstellar ice analogs: Gas-phase enrichment
We study the photo-desorption occurring in HO:CO:NH ice mixtures
irradiated with monochromatic (550 and 900 eV) and broad band (250--1250 eV)
soft X-rays generated at the National Synchrotron Radiation Research Center
(Hsinchu, Taiwan). We detect many masses photo-desorbing, from atomic hydrogen
(m/z = 1) to complex species with m/z = 69 (e.g., CHNO, CHO,
CHN), supporting the enrichment of the gas phase.
At low number of absorbed photons, substrate-mediated exciton-promoted
desorption dominates the photo-desorption yield inducing the release of weakly
bound (to the surface of the ice) species; as the number of weakly bound
species declines, the photo-desorption yield decrease about one order of
magnitude, until porosity effects, reducing the surface/volume ratio, produce a
further drop of the yield.
We derive an upper limit to the CO photo-desorption yield, that in our
experiments varies from 1.4 to 0.007 molecule photon in the range ~absorbed photons cm. We apply these findings to a
protoplanetary disk model irradiated by a central T~Tauri star
Charmed nuclei within a microscopic many-body approach
Single-particle energies of the chamed baryon are obtained in
several nuclei from the relevant self-energy constructed within the framework
of a perturbative many-body approach. Results are presented for a charmed
baryon-nucleon () potential based on a SU(4) extension of the
meson-exchange hyperon-nucleon potential of the J\"{u}lich group.
Three different models (A, B and C) of this interaction, that differ only on
the values of the couplings of the scalar meson with the charmed
baryons, are considered. Phase shifts, scattering lengths and effective ranges
are computed for the three models and compared with those predicted by the
interaction derived in Eur. Phys. A {\bf 54}, 199 (2018) from the
extrapolation to the physical pion mass of recent results of the HAL QCD
Collaboration. Qualitative agreement is found for two of the models (B and C)
considered. Our results for -nuclei are compatible with those
obtained by other authors based on different models and methods. We find a
small spin-orbit splitting of the and wave states as in the case
of single -hypernuclei. The level spacing of
single-particle energies is found to be smaller than that of the corresponding
one for hypernuclei. The role of the Coulomb potential and the effect of the
coupling of the and channels on the single-particle
properties of nuclei are also analyzed. Our results show that,
despite the Coulomb repulsion between the and the protons, even the
less attractive one of our models (model C) is able to bind the
in all the nuclei considered. The effect of the
coupling is found to be almost negligible due to the
large mass difference of the and baryons.Comment: 10 pages, 6 figures, 4 table
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