Robustness of Cucker-Smale flocking model

Consider a system of autonomous interacting agents moving in space, adjusting each own velocity as a weighted mean of the relative velocities of the other agents. In order to test the robustness of the model, we assume that each pair of agents, at each time step, can fail to connect with certain probability, the failure rate. This is a modification of the (deterministic) Flocking model introduced by Cucker and Smale in Emergent behavior in flocks, IEEE Trans. on Autom. Control, 2007, 52 (May) pp. 852-862. We prove that, if this random failures are independent in time and space, and have linear or sub-linear distance dependent rate of decay, the characteristic behavior of flocking exhibited by the original deterministic model, also holds true under random failures, for all failure rates.Comment: 9 pages, 3 figure

Guessing Less and Better: Improved Attacks on GIFT-64

GIFT-64 is a block cipher that has received a lot of attention from the community since its proposal in 2017. The attack on the highest number of rounds is a differential related-key attack on 26 rounds~\cite{DBLP:journals/tosc/SunWW21}. We studied this attack, in particular with respect to the generic framework for improving key recovery from~\cite{DBLP:conf/asiacrypt/BrollCFLN21}, and we realised that this framework, combined with an efficient parallel key guessing of interesting subsets of the key and a consequent list merging applied to the partial solutions, can improve the complexity of the attack. We propose two different trade-offs, as a result of the improved key-recovery. We believe that the techniques are quite generic and that it is possible to apply them to improve other differential attacks

Simon’s Algorithm and Symmetric Crypto: Generalizations and Automatized Applications

In this paper we deepen our understanding of how to apply Simon’s algorithm to break symmetric cryptographic primitives. On the one hand, we automate the search for new attacks. Using this approach we automatically find the first efficient key-recovery attacks against constructions like 5-round MISTY L-FK or 5-round Feistel-FK (with internal permutation) using Simon’s algorithm. On the other hand, we study generalizations of Simon’s algorithm using non-standard Hadamard matrices, with the aim to expand the quantum symmetric cryptanalysis toolkit with properties other than the periods. Our main conclusion here is that none of these generalizations can ac- complish that, and we conclude that exploiting non-standard Hadamard matrices with quantum computers to break symmetric primitives will require fundamentally new attacks

Ossicular Chain Lesions in Tympanic Perforations and Chronic Otitis Media without Cholesteatoma

The first aim was to determine the prevalence, kind, and functional effects on hearing of ossicular chain suffering (OCS) in chronic otitis without cholesteatoma (NCOM) and tympanic perforations (TP). The second aim was to correlate the findings with clinical parameters and hearing level.The study group comprised 250 consecutive patients affected by NCOM and who were subjected to tympanoplasty and never operated on before. Each patient underwent preoperative pure tone audiometry. Ossicles were evaluated during surgery. The incidence of OCS in NCOM was reported in 15-62% of the patients.Ossicular chain suffering was found in 26 out of the 250 patients included in the overall sample (10%). It was found in 7% of the patients affected by TP without otorrhea and in 19% of the patients affected by chronic ear discharge with drum perforation. OCS was found most frequently in posterior eardrum perforations and in patients with bilateral disease. The incus was the ossicle most frequently interested by resorption (92% of the patients). The air conduction threshold and air bone gap were more impaired in NCOM than in TP.Ossicular chain damages in patients with non-cholesteatomatous middle ear pathologies are not frequent and are present in no more than 10% of the patients, but lesions found were similar to those reported in patients with cholesteatoma. Otorrhea, posterior perforation, and bilateral disease can be considered as good predictors of OCS

Generic Framework for Key-Guessing Improvements

International audienceWe propose a general technique to improve the key-guessing step of several attacks on block ciphers. This is achieved by defining and studying some new properties of the associated S-boxes and by representing them as a special type of decision trees that are crucial for finding fine-grained guessing strategies for various attack vectors. We have proposed and implemented the algorithm that efficiently finds such trees, and use it for providing several applications of this approach, which include the best known attacks on Noekeon, GIFT, and RECTANGLE

SCARF: A Low-Latency Block Cipher for Secure Cache-Randomization

Randomized cache architectures have proven to significantly increase the complexity of contention-based cache side channel attacks and therefore pre\-sent an important building block for side channel secure microarchitectures. By randomizing the address-to-cache-index mapping, attackers can no longer trivially construct minimal eviction sets which are fundamental for contention-based cache attacks. At the same time, randomized caches maintain the flexibility of traditional caches, making them broadly applicable across various CPU-types. This is a major advantage over cache partitioning approaches. A large variety of randomized cache architectures has been proposed. However, the actual randomization function received little attention and is often neglected in these proposals. Since the randomization operates directly on the critical path of the cache lookup, the function needs to have extremely low latency. At the same time, attackers must not be able to bypass the randomization which would nullify the security benefit of the randomized mapping. In this paper we propose \cipher (\underline{S}ecure \underline{CA}che \underline{R}andomization \underline{F}unction), the first dedicated cache randomization cipher which achieves low latency and is cryptographically secure in the cache attacker model. The design methodology for this dedicated cache cipher enters new territory in the field of block ciphers with a small 10-bit block length and heavy key-dependency in few rounds

New Attacks from Old Distinguishers Improved Attacks on Serpent

International audienceSerpent was originally proposed in 1998 and is one of the most studied block ciphers. In this paper we improve knowledge of its security by providing the current best attack on this cipher, which is a 12-round differential-linear attack with lower data, time and memory complexities than the best previous attacks. Our improvements are based on an improved conditional key guessing technique that exploits the properties of the Sboxes

Further Improving Differential-Linear Attacks: Applications to Chaskey and Serpent

Differential-linear attacks are a cryptanalysis family that has recently benefited from various technical improvements, mainly in the context of ARX constructions. In this paper we push further this refinement, proposing several new improvements. In particular, we develop a better understanding of the related correlations, improve upon the statistics by using the LLR, and finally use ideas from conditional differentials for finding many right pairs. We illustrate the usefulness of these ideas by presenting the first 7.5-round attack on Chaskey. Finally, we present a new competitive attack on 12 rounds of Serpent, and as such the first cryptanalytic progress on Serpent in 10 years

Experiencias educativas: aplicación de diferentes plataformas virtuales como método evaluativo : Herramientas digitales que nos conectan

Introducción: Desde el inicio de la pandemia y el aislamiento preventivo debido a la presencia del COVID-19, los docentes se vieron en la necesidad de seguir formándose académicamente desde sus hogares a través de cursos y talleres online o virtuales, siempre en pro de la continuidad educativa universitaria, obteniendo futuros resultados positivos para los alumnos. El propósito de esta presentación fue explicar la experiencia transformadora en la formación continua del alumno a través de plataformas virtuales educativas como Google Forms. Objetivos: aumentar la flexibilidad del aprendizaje en términos de espacio, tiempo, recursos didácticos, y mejorar el acceso a los sistemas educativos desde la distancia.Facultad de Odontologí