Federico Pintore is a mathematician and cryptographer, currently working at the Mathematical Institute, University of Oxford (UK), as a Postdoctoral Research Assistant. His interests revolve around the various facets of Cryptography, with a particular focus on cryptographic algorithms related to elliptic curves, Number Theory and the blockchain technology. He received a PhD in Mathematics in 2015, at the University of Trento, where he managed two blockchain R&D projects while being a Postdoc. His current research mainly focuses on Post-quantum Cryptography and Isogeny-based Cryptography.

Title of talk: Lossy CSI-FiSh: a practical and provable secure isogeny-based signature

Abstract: In the last decades, elliptic curves have been a precious ally for cryptographers in the construction of secure public-key cryptosystems. Even so, with the possibility of obtaining quantum computers that could implement Shor’s quantum algorithm becoming more concrete in recent years, this happy marriage seemed to have come to an end. However, elliptic curves have been recently brought to the attention of cryptographers once again, this time to construct schemes supposed to be secure even against quantum adversaries. These schemes use isogenies (special maps) between elliptic curves, which turned out to be rather elusive for the construction of signature schemes. As a consequence, the first practical isogeny-based digital signature scheme, CSI-FiSh, was proposed only last year. In this talk I will present Lossy CSI-FiSh, a variant of CSI-FiSh with a stronger security proof and almost the same efficiency as CSI-FiSh. This new scheme was designed together with the Oxford Mathematics colleague Ali El Kaafarani and Dr. Shuichi Katsumata (AIST, JP)