Estudio y análisis del criptoanálisis lineal y diferencial: técnicas y herramientas

Este objetivo principal de este Trabajo Fin de Grado es el estudio de dos herramientas comúnmente usadas a la hora de criptoanalizar y estudiar la robustez de algoritmos de cifrado por bloques, el criptoanálisis diferencial y el criptoanálisis lineal. Además, realizamos también una serie de experimentos en los que tratamos de estudiar la fortaleza de algunos algoritmos de cifrado entrenando diferentes modelos de aprendizaje automático para que traten de emular su funcionamiento o para detectar alguna característica de los textos cifrados con estos algoritmos. El estudio del criptoanálisis diferencial está basado en el artículo Differential cryptanalysis of DESlike cryptosystems de Eli Biham y Adi Shamir, mientras que el estudio del criptoanálisis lineal está basado en el artículo Linear Cryptanalysis Method for DES Cipher de Mitsuru Matsui. Profundizamos en los fundamentos matemáticos de estos ataques, realizando la implementación de ambos en Python y concluyendo con un estudio de la complejidad de la realización de estos ataques en términos de los textos planos y cifrados necesarios para poder obtener la clave de cifrado. Para los experimentos del trabajo hemos tenido como objeto de estudio tres algoritmos de cifrado. El primero es el antiguo estándar simétrico, el DES, ya que a pesar de ser un algoritmo que a día de hoy ya no es seguro (aunque una variante, el Triple DES, se sigue usando) sigue siendo interesante por haber sido el primer cifrado simétrico moderno. El segundo es el actual estándar simétrico, el AES. Es extremadamente robusto y es el algoritmo simétrico de cifrado por bloques establecido por el NIST. El último es el Speck, uno de los algoritmos de cifrado de tipo lightweight (pensado para ejecutarse en hardware de pocos recursos) diseñado por la NSA. Hemos usado diferentes modelos de redes neuronales artifciales para evaluar y comparar la seguridad que nos ofrecen estos tres algoritmos. En resumen, en este trabajo hemos estudiado el criptoanálisis de algunos algoritmos de cifrado simétricos por bloques modernos desde su origen con los artículos de Biham, Shamir y Matsui hasta llegar a los enfoques más recientes en el criptoanálisis, en los que se aplican técnicas de aprendizaje automático para evaluar la fortaleza de este tipo de algoritmos de cifrado de manera directa (intentando aprender características de los textos cifrados, emular el comportamiento del cifrado o del descifrado del algoritmo, etc.) o usadas en combinación con ataques tradicionales mejorando su efectividad

Communication-efficient and crash-quiescent Omega with unknown membership

The failure detector class Omega (Ω) provides an eventual leader election functionality, i.e., eventually all correct processes permanently trust the same correct process. An algorithm is communication-efficient if the number of links that carry messages forever is bounded by n, being n the number of processes in the system. It has been defined that an algorithm is crash-quiescent if it eventually stops sending messages to crashed processes. In this regard, it has been recently shown the impossibility of implementing Ω crash quiescently without a majority of correct processes. We say that the membership is unknown if each process pi only knows its own identity and the number of processes in the system (that is, i and n), but pi does not know the identity of the rest of processes of the system. There is a type of link (denoted by ADD link) in which a bounded (but unknown) number of consecutive messages can be delayed or lost. In this work we present the first implementation (to our knowledge) of Ω in partially synchronous systems with ADD links and with unknown membership. Furthermore, it is the first implementation of Ω that combines two very interesting properties: communication-efficiency and crash-quiescence when the majority of processes are correct. Finally, we also obtain with the same algorithm a failure detector () such that every correct process eventually and permanently outputs the set of all correct processes

Genetic recoding to dissect the roles of site-specific protein O-GlcNAcylation

ISSN:1559-744XISSN:1559-743

Cardioprotective effect of the short-acting beta-blocker esmolol in experimental ischemia/reperfusion.

This study was funded by a grant from the Spanish Society of Cardiology “Investigación Traslacional 2017”. J.N. is a recipient of a predoctoral grant “Jordi Soler Soler” from the CIBERCV. The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence.S

Toward Systematic Literature Reviews in Hydrological Sciences

[EN] Systematic literature reviews can provide an objective global overview of background research on hydrological questions. This study presents a methodology to ensure rigor, traceability, and replicability in evaluating state-of-the-art hydrological topics. The proposed methodology involved systematic, objective, and explicit steps. Strategies with defined selection criteria were used to search the relevant literature comprehensively and accurately on hydrological uncertainty as a case study. The most pertinent documents were filtered to build a critical state-of-the-art synthesis for evaluating their quality and relevance. This methodology allows systematic literature analysis to provide an objective summary of the evidence, with a structured procedure for state-of-the-art reviews, which promotes transparency in the search, unlike typical review papers that lack reproducible methodologies that may lead to obtaining a potentially subjective reference selection. Consequently, the proposed methodology improves reference reliability and study reproducibility while generalizing the methodology. This procedure has proven effective and practical for building state-of-the-art research in the study case (State-of-the-art Uncertainty in Hydrological forecasting from 2017 to 2023) and can be considered a relevant tool in hydrology and other STEM disciplines, providing a rigorous and transparent approach that enhances evidence quality and reliability.This study was funded by the Colombian Ministry of Science, Technology, and Innovation (MINCIENCIAS) through the Call for Doctorates Abroad 885-2; the Valencian Regional Government through the WATER4CAST research project (PROMETEO/2021/074); and the Spanish Ministry of Science and Innovation through the research project TETISPREDICT (PID2022-141631OB-I00).De León-Pérez, D.; Acosta Vega, R.; Salazar Galan, SA.; Aranda Domingo, JÁ.; Francés, F. (2024). Toward Systematic Literature Reviews in Hydrological Sciences. Water. 16(3). https://doi.org/10.3390/w1603043616

Optic Nerve Topography in Multiple Sclerosis Diagnosis

To assess the added value of the optic nerve region (by using visual evoked potentials [VEPs]) to the current diagnostic criteria. From the Barcelona clinically isolated syndrome (CIS) cohort, patients with complete information to assess dissemination in space (DIS), the optic nerve region, and dissemination in time at baseline (n = 388) were selected. Modified DIS (modDIS) criteria were constructed by adding the optic nerve to the current DIS regions. The DIS and modDIS criteria were evaluated with univariable Cox proportional hazard regression analyses with the time to the second attack as the outcome. A subset of these patients who had at least 10 years of follow-up or a second attack occurring within 10 years (n = 151) were selected to assess the diagnostic performance. The analyses were also performed according to CIS topography (optic neuritis vs non-optic neuritis). The addition of the optic nerve as a fifth region improved the diagnostic performance by slightly increasing the accuracy (2017 DIS 75.5%, modDIS 78.1%) and the sensitivity (2017 DIS 79.2%, modDIS 82.3%) without lowering the specificity (2017 DIS 52.4%, modDIS 52.4%). When the analysis was conducted according to CIS topography, the modDIS criteria performed similarly in both optic neuritis and non-optic neuritis CIS. The addition of the optic nerve, assessed by VEP, as a fifth region in the current DIS criteria slightly improves the diagnostic performance because it increases sensitivity without losing specificity

Acute Capsaicin Analog Supplementation Improves 400 M and 3000 M Running Time-Trial Performance

International Journal of Exercise Science 13(2): 755-765, 2020. Objectives: Performance in running-based sport depends on the ability to perform repetitive high intensity muscle contractions. Previous studies have shown that capsaicin analog (CAP) (i.e. Capsiate) supplementation may improve this performance. The purpose of this study was to investigate the acute effect of CAP supplementation on short (400 m) and middle distance (3000 m) running time-trial performance, maximum heart rate (HR), and rate of perceived exertion (RPE). Methods: Twelve physically active men completed four randomized, double-blind trials: CAP condition (12 mg) or a placebo condition. Forty-five minutes after supplementation, the participants performed a 400- or 3000-meter running time trial. Time (in seconds) was recorded. HR was analyzed at rest and immediately post-exercise, and RPE was collected immediately after exercise. Results: For both the 400 m time-trial (CAP = 66.4 + 4.2 sec vs Placebo = 67.1 + 4.8 sec, p = 0.046) and the 3000 m time-trial (CAP = 893.9 ± 46.8 sec vs Placebo = 915.2 ± 67.6 sec, p = 0.015), the time in seconds was significantly less in the CAP compared to placebo conditions. There were no statistically significant differences for HR and RPE in any condition. Conclusion: In summary, acute CAP supplementation improved 400 m and 3000 m running time-trial performance in a distance-dependent way but without modifying the HR and RPE

Assessment of platelet REACtivity after transcatheter aortic valve replacement

OBJECTIVES: The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI. BACKGROUND: Current recommendations support short-term use of aspirin + clopidogrel for patients with severe AS undergoing TAVR despite the lack of compelling evidence. METHODS: This was a prospective, randomized, multicenter investigation. Platelet reactivity was measured at 6 different time points with the VerifyNow assay (Accriva Diagnostics, San Diego, California). HPR was defined as (P2Y12 reaction units (PRU) ≥208. Patients with HPR before TAVR were randomized to either aspirin + ticagrelor or aspirin + clopidogrel for 3 months. Patients without HPR continued with aspirin + clopidogrel (registry cohort). The primary endpoint was non-HPR status (PRU <208) in ≥70% of patients treated with ticagrelor at 90 days post-TAVR. RESULTS: A total of 68 patients were included. Of these, 48 (71%) had HPR (PRU 273 ± 09) and were randomized to aspirin + ticagrelor (n = 24, PRU 277 ± 08) or continued with aspirin + clopidogrel (n = 24, PRU 269 ± 49). The remaining 20 patients (29%) without HPR (PRU 133 ± 12) were included in the registry. Overall, platelet reactivity across all the study time points after TAVR was lower in patients randomized to ticagrelor compared with those treated with clopidogrel, including those enrolled in the registry (p < 0.001). The primary endpoint was achieved in 100% of patients with ticagrelor compared with 21% with clopidogrel (p < 0.001). Interestingly, 33% of clopidogrel responder patients at baseline developed HPR status during the first month after TAVR. CONCLUSIONS: HPR to clopidogrel is present in a considerable number of patients with AS undergoing TAVR. Ticagrelor achieves a better and faster effect, providing sustained suppression of HPR to these patients. (Platelet Reactivity After TAVI: A Multicenter Pilot Study [REAC-TAVI]; NCT02224066)