Sosa-Gómez, Guillermo
Main Affiliation
Preferred name
Sosa-Gómez, Guillermo
Official Name
Sosa Gómez, Guillermo
ORCID
0000-0001-7793-896X 
Researcher ID
ABA-2857-2020
Scopus Author ID
57202400202
46 results
Now showing 1 - 10 of 46
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, New Weak Keys with Parity Patterns in the RC4 Stream Cipher(2024); <jats:p>The RC4 cryptographic algorithm is the most extensively studied stream cipher of the past two decades. This extensive research has resulted in numerous publications, many of which identify various vulnerabilities. Although these vulnerabilities do not preclude the correct use of the algorithm, they complicate its practical implementation. In this paper, we present a novel weakness in the RC4 cipher. Our findings indicate that, for input keys exhibiting certain patterns, the parity of the values in the output permutation of the KSA can be determined with high probability from the parity of its position in the output permutation. Furthermore, the use of keys with these specific patterns leads to noticeable distortions in several bytes of the RC4 output.</jats:p>14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Explainable Glaucoma Screening via Optic Disc Localization and Comparative Class Activation Map-Based Analysis(MDPI AG, 2026-06-24) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Combined and General Methodologies of Key Space Partition for the Cryptanalysis of Block Ciphers(2024); <jats:p>This paper proposes two new methods of key space partitioning for the cryptanalysis of block ciphers. The first one is called combined methodology of key space partition (CoMeKSPar), which allows us to simultaneously set some of the first and last consecutive bits of the key. In this way, the search is performed using the remaining middle bits. CoMeKSPar is a combination of two methods already proposed in the scientific literature, the Borges, Borges, Monier (BBM) and the Tito, Borges, Borges (TBB). The second method is called the general algorithm of key space reduction (GAKSRed), which makes it possible to perform a genetic algorithm search in the space formed by the unknown bits of the key, regardless of their distribution in the binary block. Furthermore, a method of attacking block ciphers is presented for the case where some key bits are known; the basic idea is to deduce some of the remaining bits of the block. An advantage of these methods is that they allow parallel computing, which allows simultaneous searches in different sub-blocks of key bits, thereby increasing the probability of success. The experiments are performed with the KLEIN (Small) lightweight block cipher using the genetic algorithm.</jats:p>15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bit Independence Criterion Extended to Stream Ciphers(2020); ; Raisa Socorro-Llanes<jats:p>The bit independence criterion was proposed to evaluate the security of the S-boxes used in block ciphers. This paper proposes an algorithm that extends this criterion to evaluate the degree of independence between the bits of inputs and outputs of the stream ciphers. The effectiveness of the algorithm is experimentally confirmed in two scenarios: random outputs independent of the input, in which it does not detect dependence, and in the RC4 ciphers, where it detects significant dependencies related to some known weaknesses. The complexity of the algorithm is estimated based on the number of inputs l, and the dimensions, n and m, of the inputs and outputs, respectively.</jats:p>1 6Scopus© Citations 12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Selecting an Effective Entropy Estimator for Short Sequences of Bits and Bytes with Maximum Entropy(2021); <jats:p>Entropy makes it possible to measure the uncertainty about an information source from the distribution of its output symbols. It is known that the maximum Shannon’s entropy of a discrete source of information is reached when its symbols follow a Uniform distribution. In cryptography, these sources have great applications since they allow for the highest security standards to be reached. In this work, the most effective estimator is selected to estimate entropy in short samples of bytes and bits with maximum entropy. For this, 18 estimators were compared. Results concerning the comparisons published in the literature between these estimators are discussed. The most suitable estimator is determined experimentally, based on its bias, the mean square error short samples of bytes and bits.</jats:p>1Scopus© Citations 16 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A modified Multifractal Detrended Fluctuation Analysis (MFDFA) approach for multifractal analysis of precipitation(2021)Scopus© Citations 34 1 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A New Family of Boolean Functions with Good Cryptographic Properties(2021); ; Evaristo José Madarro-Capó<jats:p>In 2005, Philippe Guillot presented a new construction of Boolean functions using linear codes as an extension of the Maiorana–McFarland’s (MM) construction of bent functions. In this paper, we study a new family of Boolean functions with cryptographically strong properties, such as non-linearity, propagation criterion, resiliency, and balance. The construction of cryptographically strong Boolean functions is a daunting task, and there is currently a wide range of algebraic techniques and heuristics for constructing such functions; however, these methods can be complex, computationally difficult to implement, and not always produce a sufficient variety of functions. We present in this paper a construction of Boolean functions using algebraic codes following Guillot’s work.</jats:p>5 11Scopus© Citations 4 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Information Theory Based Evaluation of the RC4 Stream Cipher Outputs(2021); <jats:p>This paper presents a criterion, based on information theory, to measure the amount of average information provided by the sequences of outputs of the RC4 on the internal state. The test statistic used is the sum of the maximum plausible estimates of the entropies H(jt|zt), corresponding to the probability distributions P(jt|zt) of the sequences of random variables (jt)t∈T and (zt)t∈T, independent, but not identically distributed, where zt are the known values of the outputs, while jt is one of the unknown elements of the internal state of the RC4. It is experimentally demonstrated that the test statistic allows for determining the most vulnerable RC4 outputs, and it is proposed to be used as a vulnerability metric for each RC4 output sequence concerning the iterative probabilistic attack.</jats:p>Scopus© Citations 4 1 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Sustainable development and human potential: Advanced tools for practical actions(Elsevier BV, 2025-10)8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, New Test to Detect Clustered Graphical Passwords in Passpoints Based on the Perimeter of the Convex Hull(2024); <jats:p>This research paper presents a new test based on a novel approach for identifying clustered graphical passwords within the Passpoints scenario. Clustered graphical passwords are considered a weakness of graphical authentication systems, introduced by users during the registration phase, and thus it is necessary to have methods for the detection and prevention of such weaknesses. Graphical authentication methods serve as a viable alternative to the conventional alphanumeric password-based authentication method, which is susceptible to known weaknesses arising from user-generated passwords of this nature. The test proposed in this study is based on estimating the distributions of the perimeter of the convex hull, based on the hypothesis that the perimeter of the convex hull of a set of five clustered points is smaller than the one formed by random points. This convex hull is computed based on the points that users select as passwords within an image measuring 1920 × 1080 pixels, using the built-in function convhull in Matlab R2018a relying on the Qhull algorithm. The test was formulated by choosing the optimal distribution that fits the data from a total of 54 distributions, evaluated using the Kolmogorov–Smirnov, Anderson–Darling, and Chi-squared tests, thus achieving the highest reliability. Evaluating the effectiveness of the proposed test involves estimating type I and II errors, for five levels of significance α∈{0.01,0.02,0.05,0.1,0.2}, by simulating datasets of random and clustered graphical passwords with different levels of clustering. In this study, we compare the effectiveness and efficiency of the proposed test with existing tests from the literature that can detect this type of pattern in Passpoints graphical passwords. Our findings indicate that the new test demonstrates a significant improvement in effectiveness compared to previously published tests. Furthermore, the joint application of the two tests also shows improvement. Depending on the significance level determined by the user or system, the enhancement results in a higher detection rate of clustered passwords, ranging from 0.1% to 8% compared to the most effective previous methods. This improvement leads to a decrease in the estimated probability of committing a type II error. In terms of efficiency, the proposed test outperforms several previous tests; however, it falls short of being the most efficient, using computation time measured in seconds as a metric. It can be concluded that the newly developed test demonstrates the highest effectiveness and the second-highest efficiency level compared to the other tests available in the existing literature for the same purpose. The test was designed to be implemented in graphical authentication systems to prevent users from selecting weak graphical passwords, enhance password strength, and improve system security.</jats:p>11