201 research outputs found
Anthropisation et dynamique des paysages en zone soudanienne au nord du Bénin
Peer reviewe
What drives consumer participation to loyalty programs? A conjoint analytical approach
Little is known about the way in which different loyalty program attributes underlie consumers' intentions to participate in such a program. Based upon equity theory, the current study distinguished between consumer inputs (personal data release, participation cost, purchase frequency, participation exclusivity, and participation efforts) and outputs (program) benefits, number of program providers, and program duration) as underlying attributes potentially affecting participation in a loyalty program. Using conjoint analysis, we explored how different levels within each of these eight attributes affect consumers' intentions to participate. The study holds major implications for the design of successful customer loyalty programs. Keywords: Relationship Marketing, Customer Loyalty Program, Equity Theory, Conjoint Analysis
Effets de lisière et sex-ratio de rongeurs forestiers dans un écosystème fragmenté en République Démocratique du Congo (Réserve de Masako, Kisangani)
Peer reviewe
Practical free-start collision attacks on 76-step SHA-1
In this paper we analyze the security of the compression function
of SHA-1 against collision attacks, or equivalently free-start collisions
on the hash function. While a lot of work has been dedicated to the analysis
of SHA-1 in the past decade, this is the first time that free-start collisions
have been considered for this function. We exploit the additional
freedom provided by this model by using a new start-from-the-middle
approach in combination with improvements on the cryptanalysis tools
that have been developed for SHA-1 in the recent years. This results in
particular in better differential paths than the ones used for hash function
collisions so far. Overall, our attack requires about evaluations
of the compression function in order to compute a one-block free-start
collision for a 76-step reduced version, which is so far the highest number
of steps reached for a collision on the SHA-1 compression function.
We have developed an efficient GPU framework for the highly branching
code typical of a cryptanalytic collision attack and used it in an optimized
implementation of our attack on recent GTX 970 GPUs. We report
that a single cheap US\$ 350 GTX 970 is sufficient to find the collision in
less than 5 days. This showcases how recent mainstream GPUs seem to
be a good platform for expensive and even highly-branching cryptanalysis
computations. Finally, our work should be taken as a reminder that
cryptanalysis on SHA-1 continues to improve. This is yet another proof
that the industry should quickly move away from using this function
Détermination des zones potentielles de conservation de la biodiversité : un aperçu sur l’approche méthodologique basée sur la diversité spécifique et les espèces endémiques
peer reviewe
KLEIN: A New Family of Lightweight Block Ciphers
Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact
Cryptanalysis of FlexAEAD
This paper analyzes the internal keyed permutation of FlexAEAD which is a round-1 candidate of the NIST LightWeight Cryptography Competition. In our analysis, we report an iterated truncated differential leveraging on a particular property of the AES S-box that becomes useful due to the particular nature of the diffusion layer of the round function. The differential holds with a low probability of 2^-7 for one round which allows it to penetrate the same number of rounds as claimed by the designers, but with a much lower complexity. Moreover, it can be easily extended to a key-recovery attack at a little extra cost. We further report a Super-Sbox construction in the internal permutation, which is exploited using the Yoyo game to devise a 6-round deterministic distinguisher and a 7-round key recovery attack for the 128-bit internal permutation. Similar attacks can be mounted for the 64-bit and 256-bit variants. All these attacks outperform the existing results of the designers as well as other third-party results. The iterated truncated differentials can be tweaked to mount forgery attacks similar to the ones given by Eichlseder et al Success probabilities of all the reported distinguishing attacks are shown to be high. All practical attacks have been experimentally verified. To the best of our knowledge, this work reports the first key-recovery attack on the internal keyed permutation of FlexAEAD
Effets de lisière et sex-ratio de rongeurs forestiers dans un écosystème fragmenté en République Démocratique du Congo (Réserve de Masako, Kisangani)
Edge Effects and Sex Ratio of Forest Rodents in a Fragmented Ecosystem in the Democratic Republic of the Congo (Masako Reserve, Kisangani). A study of edge effects on the sex ratios of six species of rodents was undertaken in the Masako reserve located at 15 km from Kisangani in the DRC. 1789 individuals collected during two years were used to analyze the sex ratio in a fallow land, a secondary forest and in the edge zone between the fallow land and the secondary forest. The results were compared with a uniform distribution using a χ² test. Males were more captured for all species except for Lophuromys dudui. An overall sex ratio significantly in favor of males is observed from one year to another. Overall, the sex ratio is not statistically different from 1/1 for Deomys, Hybomys and Lophuromys but significantly greater than 1/1 for Hylomyscus and Stochomys. For Praomys, it is significantly greater than 1/1 in 2010 but not in 2011. The males of Hylomyscus, Praomys and Stochomys and the females of Lophuromys were more frequent in the three habitats. The edge habitat was characterized by a predominance of females of Deomys and sex ratios not different from 1/1 for Hylomyscus but significantly different from 1/1 for Praomys and Stochomys. The differences in sex ratio recorded between the edge zone and its adjacent habitats for Hylomyscus, Stochomys and Praomys prove an edge effect
Polytopic Cryptanalysis
Standard differential cryptanalysis uses statistical dependencies between the difference of two plaintexts and the difference of the respective two ciphertexts to attack a cipher. Here we introduce polytopic cryptanalysis which considers interdependencies between larger sets of texts as they traverse through the cipher. We prove that the methodology of standard differential cryptanalysis can unambiguously be extended and transferred to the polytopic case including impossible differentials. We show that impossible polytopic transitions have generic advantages over impossible differentials. To demonstrate the practical relevance of the generalization, we present new low-data attacks on round-reduced DES and AES using impossible polytopic transitions that are able to compete with existing attacks, partially outperforming these
Cube Testers and Key Recovery Attacks On Reduced-Round MD6 and Trivium
CRYPTO 2008 saw the introduction of the hash function
MD6 and of cube attacks, a type of algebraic attack applicable to cryptographic
functions having a low-degree algebraic normal form over GF(2).
This paper applies cube attacks to reduced round MD6, finding the full
128-bit key of a 14-round MD6 with complexity 2^22 (which takes less
than a minute on a single PC). This is the best key recovery attack announced
so far for MD6. We then introduce a new class of attacks called
cube testers, based on efficient property-testing algorithms, and apply
them to MD6 and to the stream cipher Trivium. Unlike the standard
cube attacks, cube testers detect nonrandom behavior rather than performing
key extraction, but they can also attack cryptographic schemes
described by nonrandom polynomials of relatively high degree. Applied
to MD6, cube testers detect nonrandomness over 18 rounds in 2^17 complexity;
applied to a slightly modified version of the MD6 compression
function, they can distinguish 66 rounds from random in 2^24 complexity.
Cube testers give distinguishers on Trivium reduced to 790 rounds from
random with 2^30 complexity and detect nonrandomness over 885 rounds
in 2^27, improving on the original 767-round cube attack
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