arXiv
(422,153 recursos)
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Mostrando recursos 181 - 200 de 9,277
181.
An Improved Remote User Authentication Scheme Using Smart Cards - Kumar, Manoj
In 2000, Hwang and Li proposed a new remote user authentication scheme using
smart cards. In the same year, Chan and Cheng pointed out that Hwang and
Li’s scheme is not secure against the masquerade attack. Further, in
2003, Shen, Lin and Hwang pointed out a different type of attack on Hwang and
Li’s scheme and presented a modified scheme to remove its security
pitfalls. This paper presents an improved scheme which is secure against
Chan-Cheng and all the extended attacks.
182.
The Modified Scheme is still vulnerable to the parallel Session Attack - Kumar, Manoj
In 2002, Chien–Jan–Tseng introduced an efficient remote user
authentication scheme using smart cards. Further, in 2004, W. C. Ku and S. M.
Chen proposed an efficient remote user authentication scheme using smart cards
to solve the security problems of Chien et al.’s scheme. Recently, Hsu
and Yoon et al. pointed out the security weakness of the Ku and Chen’s
scheme Furthermore, Yoon et al. modified the password change phase of Ku and
Chen’s scheme and they also proposed a new efficient remote user
authentication scheme using smart cards. This paper analyzes that the modified
scheme of Yoon et al. still vulnerable to parallel session attack.
183.
Adaptive Online Prediction by Following the Perturbed Leader - Hutter, Marcus; Poland, Jan
When applying aggregating strategies to Prediction with Expert Advice, the
learning rate must be adaptively tuned. The natural choice of
sqrt(complexity/current loss) renders the analysis of Weighted Majority
derivatives quite complicated. In particular, for arbitrary weights there have
been no results proven so far. The analysis of the alternative "Follow the
Perturbed Leader" (FPL) algorithm from Kalai & Vempala (2003) (based on
Hannan's algorithm) is easier. We derive loss bounds for adaptive learning rate
and both finite expert classes with uniform weights and countable expert
classes with arbitrary weights. For the former setup, our loss bounds match the
best known results so far, while for the latter our results...
184.
On the Unicity Distance of Stego Key - Weiming, Zhang; Shiqu, Li
Steganography is about how to send secret message covertly. And the purpose
of steganalysis is to not only detect the existence of the hidden message but
also extract it. So far there have been many reliable detecting methods on
various steganographic algorithms, while there are few approaches that can
extract the hidden information. In this paper, the difficulty of extracting
hidden information, which is essentially a kind of privacy, is analyzed with
information-theoretic method in the terms of unicity distance of steganographic
key (abbreviated stego key). A lower bound for the unicity distance is
obtained, which shows the relations between key rate, message rate, hiding
capacity and difficulty of...
186.
A Probabilistic Upper Bound on Differential Entropy - DeStefano, Joseph; Learned-Miller, Erik
A novel, non-trivial, probabilistic upper bound on the entropy of an unknown
one-dimensional distribution, given the support of the distribution and a
sample from that distribution, is presented. No knowledge beyond the support of
the unknown distribution is required, nor is the distribution required to have
a density. Previous distribution-free bounds on the cumulative distribution
function of a random variable given a sample of that variable are used to
construct the bound. A simple, fast, and intuitive algorithm for computing the
entropy bound from a sample is provided.
187.
A Multi-proxy Signature Scheme for Partial delegation with Warrant - Awasthi, Amit K; Lal, Sunder
In some cases, the original signer may delegate its signing power to a
specified proxy group while ensuring individual accountability of each
participantsigner. The proxy signature scheme that achieves such purpose is
called the multi-proxy signature scheme and the signature generated by the
specified proxy group is called multi-proxy signature for the original signer.
Recently such scheme has been discussed by Lin et al. Lins scheme is based on
partial delegation by Mambo et al. In present chapter we introduce a new
multi-proxy signature scheme, which requires less computational overhead in
comparison to Lin et al, and also fulfill the requirement of partial delegation
with warrant simultaneously.
188.
A DNA Sequence Compression Algorithm Based on LUT and LZ77 - Bao, Sheng; Chen, Shi; Jing, Zhiqiang; Ren, Ran
This article introduces a new DNA sequence compression algorithm which is
based on LUT and LZ77 algorithm. Combined a LUT-based pre-coding routine and
LZ77 compression routine,this algorithm can approach a compression ratio of
1.9bits \slash base and even lower.The biggest advantage of this algorithm is
fast execution, small memory occupation and easy implementation.
189.
Wikis in Tuple Spaces - Worley III, G Gordon
We consider storing the pages of a wiki in a tuple space and the effects this
might have on the wiki experience. In particular, wiki pages are stored in
tuples with a few identifying values such as title, author, revision date,
content, etc. and pages are retrieved by sending the tuple space templates,
such as one that gives the title but nothing else, leaving the tuple space to
resolve to a single tuple. We use a tuple space wiki to avoid deadlocks,
infinite loops, and wasted efforts when page edit contention arises and examine
how a tuple space wiki changes the wiki experience.
190.
Efficient and Robust Geocasting Protocols for Sensor Networks - Seada, Karim; Helmy, Ahmed
Geocasting is the delivery of packets to nodes within a certain geographic
area. For many applications in wireless ad hoc and sensor networks, geocasting
is an important and frequent communication service. The challenging problem in
geocasting is distributing the packets to all the nodes within the geocast
region with high probability but with low overhead. According to our study we
notice a clear tradeoff between the proportion of nodes in the geocast region
that receive the packet and the overhead incurred by the geocast packet
especially at low densities and irregular distributions. We present two novel
protocols for geocasting that achieve high delivery rate and low overhead by
utilizing...
191.
Adaptive Codes: A New Class of Non-standard Variable-length Codes - Trinca, Dragos
We introduce a new class of non-standard variable-length codes, called
adaptive codes. This class of codes associates a variable-length codeword to
the symbol being encoded depending on the previous symbols in the input data
string. An efficient algorithm for constructing adaptive codes of order one is
presented. Then, we introduce a natural generalization of adaptive codes,
called GA codes.
192.
SWiM: A Simple Window Mover - Chang, Tony; Cook, Damon; Su, Ramona
As computers become more ubiquitous, traditional two-dimensional interfaces
must be replaced with interfaces based on a three-dimensional metaphor.
However, these interfaces must still be as simple and functional as their
two-dimensional predecessors. This paper introduces SWiM, a new interface for
moving application windows between various screens, such as wall displays,
laptop monitors, and desktop displays, in a three-dimensional physical
environment. SWiM was designed based on the results of initial "paper and
pencil" user tests of three possible interfaces. The results of these tests led
to a map-like interface where users select the destination display for their
application from various icons. If the destination is a mobile display it is
not...
193.
Visual Character Recognition using Artificial Neural Networks - Araokar, Shashank
The recognition of optical characters is known to be one of the earliest
applications of Artificial Neural Networks, which partially emulate human
thinking in the domain of artificial intelligence. In this paper, a simplified
neural approach to recognition of optical or visual characters is portrayed and
discussed. The document is expected to serve as a resource for learners and
amateur investigators in pattern recognition, neural networking and related
disciplines.
194.
Point set stratification and Delaunay depth - Abellanas, Manuel; Claverol, Mercè; Hurtado, Ferran
In the study of depth functions it is important to decide whether we want
such a function to be sensitive to multimodality or not. In this paper we
analyze the Delaunay depth function, which is sensitive to multimodality and
compare this depth with others, as convex depth and location depth. We study
the stratification that Delaunay depth induces in the point set (layers) and in
the whole plane (levels), and we develop an algorithm for computing the
Delaunay depth contours, associated to a point set in the plane, with running
time O(n log^2 n). The depth of a query point p with respect to a data set...
195.
Temporal and Spatial Data Mining with Second-Order Hidden Models - Mari, Jean-Francois; Ber, Florence Le
In the frame of designing a knowledge discovery system, we have developed
stochastic models based on high-order hidden Markov models. These models are
capable to map sequences of data into a Markov chain in which the transitions
between the states depend on the \texttt{n} previous states according to the
order of the model. We study the process of achieving information extraction
fromspatial and temporal data by means of an unsupervised classification. We
use therefore a French national database related to the land use of a region,
named Teruti, which describes the land use both in the spatial and temporal
domain. Land-use categories (wheat, corn, forest, ...) are logged...
196.
Artificial Neural Networks and their Applications - Malik, Nitin
The Artificial Neural network is a functional imitation of simplified model
of the biological neurons and their goal is to construct useful computers for
real world problems. The ANN applications have increased dramatically in the
last few years fired by both theoretical and practical applications in a wide
variety of applications. A brief theory of ANN is presented and potential areas
are identified and future trends are discussed.
197.
State Space Computation and Analysis of Time Petri Nets - Gardey, Guillaume; Roux, Olivier H.; Roux, Olivier F.
The theory of Petri Nets provides a general framework to specify the
behaviors of real-time reactive systems and Time Petri Nets were introduced to
take also temporal specifications into account. We present in this paper a
forward zone-based algorithm to compute the state space of a bounded Time Petri
Net: the method is different and more efficient than the classical State Class
Graph. We prove the algorithm to be exact with respect to the reachability
problem. Furthermore, we propose a translation of the computed state space into
a Timed Automaton, proved to be timed bisimilar to the original Time Petri Net.
As the method produce a single Timed...
198.
Logic Column 12: Logical Verification and Equational Verification - Pucella, Riccardo
This article examines two approaches to verification, one based on using a
logic for expressing properties of a system, and one based on showing the
system equivalent to a simpler system that obviously has whatever property is
of interest. Using examples such as process calculi and regular programs, the
relationship between these two approaches is explored.
199.
Equivalence-Checking on Infinite-State Systems: Techniques and Results - Kucera, Antonin; Jancar, Petr
The paper presents a selection of recently developed and/or used techniques
for equivalence-checking on infinite-state systems, and an up-to-date overview
of existing results (as of September 2004).
200.
Automatic Verification of Timed Concurrent Constraint Programs - Falaschi, Moreno; Villanueva, Alicia
The language Timed Concurrent Constraint (tccp) is the extension over time of
the Concurrent Constraint Programming (cc) paradigm that allows us to specify
concurrent systems where timing is critical, for example reactive systems.
Systems which may have an infinite number of states can be specified in tccp.
Model checking is a technique which is able to verify finite-state systems with
a huge number of states in an automatic way. In the last years several studies
have investigated how to extend model checking techniques to systems with an
infinite number of states. In this paper we propose an approach which exploits
the computation model of tccp. Constraint based computations...
181.
