67 research outputs found
Lyapunov exponent evaluation of a digital watermarking scheme proven to be secure
In our previous researches, a new digital watermarking scheme based on
chaotic iterations has been introduced. This scheme was both stego-secure and
topologically secure. The stego-security is to face an attacker in the
"watermark only attack" category, whereas the topological security concerns
other categories of attacks. Its Lyapunov exponent is evaluated here, to
quantify the chaos generated by this scheme.
Keywords : Lyapunov exponent; Information hiding; Security; Chaotic
iterations; Digital Watermarking.Comment: 10 page
Chaotic iterations versus Spread-spectrum: chaos and stego security
A new framework for information hiding security, called chaos-security, has
been proposed in a previous study. It is based on the evaluation of
unpredictability of the scheme, whereas existing notions of security, as
stego-security, are more linked to information leaks. It has been proven that
spread-spectrum techniques, a well-known stego-secure scheme, are chaos-secure
too. In this paper, the links between the two notions of security is deepened
and the usability of chaos-security is clarified, by presenting a novel data
hiding scheme that is twice stego and chaos-secure. This last scheme has better
scores than spread-spectrum when evaluating qualitative and quantitative
chaos-security properties. Incidentally, this result shows that the new
framework for security tends to improve the ability to compare data hiding
scheme
Application of Steganography for Anonymity through the Internet
In this paper, a novel steganographic scheme based on chaotic iterations is
proposed. This research work takes place into the information hiding security
framework. The applications for anonymity and privacy through the Internet are
regarded too. To guarantee such an anonymity, it should be possible to set up a
secret communication channel into a web page, being both secure and robust. To
achieve this goal, we propose an information hiding scheme being stego-secure,
which is the highest level of security in a well defined and studied category
of attacks called "watermark-only attack". This category of attacks is the best
context to study steganography-based anonymity through the Internet. The
steganalysis of our steganographic process is also studied in order to show it
security in a real test framework.Comment: 14 page
Probing photon structure in DVCS on a photon target
The factorization of the amplitude for the deeply virtual Compton scattering
(DVCS) process gamma*(Q) gamma -> gamma gamma at high Q2 is demonstrated in two
distinct kinematical domains, allowing to define the photon generalized parton
distributions and the diphoton generalized distribution amplitudes. Both these
quantities exhibit an anomalous scaling behaviour and obey new inhomogeneous
QCD evolution equations.Comment: 3 pages, 1 figure, to be published in the proceedings of the PANIC
2008 conference, Eilat (Israel), November 200
Photon Generalized Parton Distributions
We present a calculation of the generalized parton distributions of the
photon using overlaps of photon light-front wave functions.Comment: Talk given at LightCone 2011, 4 pages, 3 figure
Duality violations and spectral sum rules
We study the issue of duality violations in the VV-AA vacuum polarization
function in the chiral limit. This is done with the help of a model with an
expansion in inverse powers of the number of colors, Nc, allowing us to
consider resonances with a finite width. Due to these duality violations, the
Operator Product Expansion (OPE) and the moments of the spectral function (e.g.
the Weinberg sum rules) do not match at finite momentum, and we analyze this
difference in detail. We also perform a comparative study of many of the
different methods proposed in the literature for the extraction of the OPE
parameters and find that, when applied to our model, they all fare quite
similarly. In fact, the model strongly suggests that a significant improvement
in precision can only be expected after duality violations are included. To
this end, we propose a method to parameterize these duality violations. The
method works quite well for the model, and we hope that it may also be useful
in future determinations of OPE parameters in QCD.Comment: 29 pages, 9 figures, LateX file. Small changes to match journal
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