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X-WR-CALNAME:GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen
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X-WR-CALDESC:évènements pour GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen
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TZID:Europe/Paris
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DTSTART:20250330T010000
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DTSTART;TZID=Europe/Paris:20250604T140000
DTEND;TZID=Europe/Paris:20250604T150000
DTSTAMP:20260504T190531
CREATED:20250520T084501Z
LAST-MODIFIED:20250520T084501Z
UID:11867-1749045600-1749049200@www.greyc.fr
SUMMARY:Neily Sanon - L’identification et la mesure des biais dans les systèmes de reconnaissance facial
DESCRIPTION:Facial recognition systems exhibit varying levels of performance depending on demographic characteristics such as gender\, age\, or ethnic origin. These biases\, extensively documented in empirical studies\, raise critical concerns regarding reliability\, fairness\, and ethical compliance. \nThis presentation will examine the underlying sources of these biases\, whether they stem from dataset composition\, algorithmic choices\, or intersectional factors. It will also explore the different evaluation methods used to quantify performance disparities across groups\, along with mitigation strategies that can be applied at various stages of the processing pipeline Particular attention will be given to emerging certification mechanisms\, as regulatory authorities begin to incorporate bias evaluation into their assessment and approval processes.
URL:https://www.greyc.fr/event/neily-sanon-lidentification-et-la-mesure-des-biais-dans-les-systemes-de-reconnaissance-facial/
LOCATION:Sciences 3- S3 351
CATEGORIES:General,News,Safe,Séminaire Cryptologie et sécurité
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20250611T140000
DTEND;TZID=Europe/Paris:20250611T150000
DTSTAMP:20260504T190531
CREATED:20250527T091248Z
LAST-MODIFIED:20250527T190334Z
UID:11874-1749650400-1749654000@www.greyc.fr
SUMMARY:Henry Bambury - Polytopes in the Fiat-Shamir with Aborts Paradigm
DESCRIPTION:Post-quantum digital signatures have sparked a lot of interest in the cryptographic community in recent years. Both the NIST-selected signature Dilithium and Heatae\, winner of the Korean PQC competition\, rely on hardness of lattice problems and employ the Fiat-Shamir with Aborts paradigm\, in which rejection sampling is used to eliminate a secret’s dependency on a given source distribution. The distribution used to conceal the secret has direct consequences on signature performances\, such as size\, speed and simplicity. Dilithium uses a simple hypercube uniform sampler\, while Haetae improves signature sizes by using a significantly more complex sampler based on Euclidean balls. In this work\, we propose a framework relying on uniform sampling in polytopes\, and use it to instantiate a new signature scheme: Patronus. Patronus acts as a tradeoff between both standards\, offering improved signature sizes compared to Dilithium\, while using a sampler that is much simpler than Haetae’s\, as it avoids the need for Gaussian sampling.
URL:https://www.greyc.fr/event/henry-bambury-polytopes-in-the-fiat-shamir-with-aborts-paradigm/
LOCATION:Sciences 3- S3 351
CATEGORIES:General,News,Safe,Séminaire Cryptologie et sécurité
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20250618T140000
DTEND;TZID=Europe/Paris:20250618T150000
DTSTAMP:20260504T190531
CREATED:20250611T114554Z
LAST-MODIFIED:20250611T114554Z
UID:11889-1750255200-1750258800@www.greyc.fr
SUMMARY:Alban Gilard - Computation of the Hilbert Series for the Support-Minors Modeling of the MinRank Problem
DESCRIPTION:The MinRank problem is a simple linear algebra problem: given matrices with coefficients in a field\, find a non trivial linear combina- tion of the matrices that has a small rank. There are several algebraic modeling of the problem. The main ones are: the Kipnis-Shamir modeling\, the Minors modeling and the Support-Minors modeling. The Minors modeling has already been studied a lot\, we know a precise analysis of the complexity of computing a Gröbner basis of the modeling\, through the computation of the exact Hilbert Series for a generic instance. For the Support-Minors modeling\, the first terms of the Hilbert Series were known since 2020\, based on an heuristic and experimental work. Here\, we provide a formula and a proof for the complete Hilbert Series of the Support Minors modeling for generic instances. This is done by adapting well known results on determinantal ideals to an ideal generated by a particular subset of the set of all minors of a matrix of variables. We then show that this ideal is generated by standard monomials having a particular shape\, and derive the Hilbert Series by counting the number of such standard monomials. Following the work done for the Minors Modeling\, we then transfer the properties of this particular determinantal ideal to ideals generated by the Support Minors system\, by adding generic forms. This work allows to make a precise comparison between the Minors and Support Minors modeling\, and a precise estimate of the complex- ity of solving MinRank instances for the parameters of the Mirath signature scheme that is currently at the second round of the NIST standardization process for Additional Digital Signature Schemes.
URL:https://www.greyc.fr/event/alban-gilard-computation-of-the-hilbert-series-for-the-support-minors-modeling-of-the-minrank-problem/
LOCATION:Sciences 3- S3 351
CATEGORIES:General,News,Safe,Séminaire Cryptologie et sécurité
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