CRYPTO CAFÉ 

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Past Presentations

September 2, 2025, 10:00 am  Science Building (SE-43), room 215    

Speaker: Hansraj Jangir, Ph.D. student, Florida Atlantic University                     

Title: A Quasi-polynomial time Quantum Algorithm for the Extrapolated Dihedral Coset Problem.      FLYER  

Abstract: The Learning With Errors (LWE) problem, introduced by Regev (STOC’05), is one of the fundamental problems in lattice-based cryptography, believed to be hard even for quantum adversaries. Regev (FOCS’02) showed that LWE reduces to the quantum Dihedral Coset Problem (DCP) and later, Brakerski et al. (PKC 2018) extended this to the more general Extrapolated Dihedral Coset Problem (EDCP). In this talk, we present a quasi-polynomial time quantum algorithm for solving EDCP over power-of-two moduli, using a quasi-polynomial number of samples. We stress that our algorithm does not affect the security of LWE with standard parameters, as the reduction from standard LWE to EDCP limits the number of samples to be polynomial. 

Bio: Hansraj is a PhD student in the Department of Mathematics and Statistics at Florida Atlantic University, Boca Raton. Prior to starting his doctoral studies, he worked as a Junior Research Fellow at the Defense Research and Development Organization (DRDO), Delhi. His research interests include lattice based cryptography and quantum algorithms.

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