71,074 research outputs found
On formal verification of arithmetic-based cryptographic primitives
Cryptographic primitives are fundamental for information security: they are
used as basic components for cryptographic protocols or public-key
cryptosystems. In many cases, their security proofs consist in showing that
they are reducible to computationally hard problems. Those reductions can be
subtle and tedious, and thus not easily checkable. On top of the proof
assistant Coq, we had implemented in previous work a toolbox for writing and
checking game-based security proofs of cryptographic primitives. In this paper
we describe its extension with number-theoretic capabilities so that it is now
possible to write and check arithmetic-based cryptographic primitives in our
toolbox. We illustrate our work by machine checking the game-based proofs of
unpredictability of the pseudo-random bit generator of Blum, Blum and Shub, and
semantic security of the public-key cryptographic scheme of Goldwasser and
Micali.Comment: 13 page
Recovering Grammar Relationships for the Java Language Specification
Grammar convergence is a method that helps discovering relationships between
different grammars of the same language or different language versions. The key
element of the method is the operational, transformation-based representation
of those relationships. Given input grammars for convergence, they are
transformed until they are structurally equal. The transformations are composed
from primitive operators; properties of these operators and the composed chains
provide quantitative and qualitative insight into the relationships between the
grammars at hand. We describe a refined method for grammar convergence, and we
use it in a major study, where we recover the relationships between all the
grammars that occur in the different versions of the Java Language
Specification (JLS). The relationships are represented as grammar
transformation chains that capture all accidental or intended differences
between the JLS grammars. This method is mechanized and driven by nominal and
structural differences between pairs of grammars that are subject to
asymmetric, binary convergence steps. We present the underlying operator suite
for grammar transformation in detail, and we illustrate the suite with many
examples of transformations on the JLS grammars. We also describe the
extraction effort, which was needed to make the JLS grammars amenable to
automated processing. We include substantial metadata about the convergence
process for the JLS so that the effort becomes reproducible and transparent
On the Simulatability Condition in Key Generation Over a Non-authenticated Public Channel
Simulatability condition is a fundamental concept in studying key generation
over a non-authenticated public channel, in which Eve is active and can
intercept, modify and falsify messages exchanged over the non-authenticated
public channel. Using this condition, Maurer and Wolf showed a remarkable "all
or nothing" result: if the simulatability condition does not hold, the key
capacity over the non-authenticated public channel will be the same as that of
the case with a passive Eve, while the key capacity over the non-authenticated
channel will be zero if the simulatability condition holds. However, two
questions remain open so far: 1) For a given joint probability mass function
(PMF), are there efficient algorithms (polynomial complexity algorithms) for
checking whether the simulatability condition holds or not?; and 2) If the
simulatability condition holds, are there efficient algorithms for finding the
corresponding attack strategy? In this paper, we answer these two open
questions affirmatively. In particular, for a given joint PMF, we construct a
linear programming (LP) problem and show that the simulatability condition
holds \textit{if and only if} the optimal value obtained from the constructed
LP is zero. Furthermore, we construct another LP and show that the minimizer of
the newly constructed LP is a valid attack strategy. Both LPs can be solved
with a polynomial complexity
Catalyst-assisted Probabilistic Entanglement Transformation
We are concerned with catalyst-assisted probabilistic entanglement
transformations. A necessary and sufficient condition is presented under which
there exist partial catalysts that can increase the maximal transforming
probability of a given entanglement transformation. We also design an algorithm
which leads to an efficient method for finding the most economical partial
catalysts with minimal dimension. The mathematical structure of
catalyst-assisted probabilistic transformation is carefully investigated.Comment: 12 page
Systematization of a 256-bit lightweight block cipher Marvin
In a world heavily loaded by information, there is a great need for keeping
specific information secure from adversaries. The rapid growth in the research
field of lightweight cryptography can be seen from the list of the number of
lightweight stream as well as block ciphers that has been proposed in the
recent years. This paper focuses only on the subject of lightweight block
ciphers. In this paper, we have proposed a new 256 bit lightweight block cipher
named as Marvin, that belongs to the family of Extended LS designs.Comment: 12 pages,6 figure
Privacy-Preserving Outsourcing of Large-Scale Nonlinear Programming to the Cloud
The increasing massive data generated by various sources has given birth to
big data analytics. Solving large-scale nonlinear programming problems (NLPs)
is one important big data analytics task that has applications in many domains
such as transport and logistics. However, NLPs are usually too computationally
expensive for resource-constrained users. Fortunately, cloud computing provides
an alternative and economical service for resource-constrained users to
outsource their computation tasks to the cloud. However, one major concern with
outsourcing NLPs is the leakage of user's private information contained in NLP
formulations and results. Although much work has been done on
privacy-preserving outsourcing of computation tasks, little attention has been
paid to NLPs. In this paper, we for the first time investigate secure
outsourcing of general large-scale NLPs with nonlinear constraints. A secure
and efficient transformation scheme at the user side is proposed to protect
user's private information; at the cloud side, generalized reduced gradient
method is applied to effectively solve the transformed large-scale NLPs. The
proposed protocol is implemented on a cloud computing testbed. Experimental
evaluations demonstrate that significant time can be saved for users and the
proposed mechanism has the potential for practical use.Comment: Ang Li and Wei Du equally contributed to this work. This work was
done when Wei Du was at the University of Arkansas. 2018 EAI International
Conference on Security and Privacy in Communication Networks (SecureComm
Folding Alternant and Goppa Codes with Non-Trivial Automorphism Groups
The main practical limitation of the McEliece public-key encryption scheme is
probably the size of its key. A famous trend to overcome this issue is to focus
on subclasses of alternant/Goppa codes with a non trivial automorphism group.
Such codes display then symmetries allowing compact parity-check or generator
matrices. For instance, a key-reduction is obtained by taking quasi-cyclic (QC)
or quasi-dyadic (QD) alternant/Goppa codes. We show that the use of such
symmetric alternant/Goppa codes in cryptography introduces a fundamental
weakness. It is indeed possible to reduce the key-recovery on the original
symmetric public-code to the key-recovery on a (much) smaller code that has not
anymore symmetries. This result is obtained thanks to a new operation on codes
called folding that exploits the knowledge of the automorphism group. This
operation consists in adding the coordinates of codewords which belong to the
same orbit under the action of the automorphism group. The advantage is
twofold: the reduction factor can be as large as the size of the orbits, and it
preserves a fundamental property: folding the dual of an alternant (resp.
Goppa) code provides the dual of an alternant (resp. Goppa) code. A key point
is to show that all the existing constructions of alternant/Goppa codes with
symmetries follow a common principal of taking codes whose support is globally
invariant under the action of affine transformations (by building upon prior
works of T. Berger and A. D{\"{u}}r). This enables not only to present a
unified view but also to generalize the construction of QC, QD and even
quasi-monoidic (QM) Goppa codes. All in all, our results can be harnessed to
boost up any key-recovery attack on McEliece systems based on symmetric
alternant or Goppa codes, and in particular algebraic attacks.Comment: 19 page
Gaussian Operations and Privacy
We consider the possibilities offered by Gaussian states and operations for
two honest parties, Alice and Bob, to obtain privacy against a third
eavesdropping party, Eve. We first extend the security analysis of the protocol
proposed in M. Navascues et al., Phys. Rev. Lett. 94, 010502 (2005). Then, we
prove that a generalized version of this protocol does not allow to distill a
secret key out of bound entangled Gaussian states
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