Search

We describe a framework for constructing an efficient non-interactive key exchange (NIKE) protocol for n parties for any n ≥ 2. Our approach is based on the problem of computing isogenies between isogenous elliptic curves, which is believed to be difficult. We do not obtain a working protocol because of a missing step that is currently an open mathematical problem. What we need to complete our protocol is an efficient algorithm that takes as input an abelian variety presented as a product of isogenous elliptic curves, and outputs an isomorphism invariant of the abelian variety.

In this paper, we present a variant of Diem's O˜(q)${\widetilde{O}(q)}$ index calculus algorithm to attack the discrete logarithm problem (DLP) in Jacobians of genus 3 non-hyperelliptic curves over a finite field 𝔽q. We implement this new variant in C++ and study the complexity in both theory and practice, making the logarithmic factors and constants hidden in the O˜-notation precise. Our variant improves the computational complexity at the cost of a moderate increase in memory consumption, but we also improve the computational complexity even when we limit the memory usage to that of Diem's original algorithm. Finally, we examine how parallelization can help to reduce both the memory cost per computer and the running time for our algorithms.

In 2017, we decided to start the annual series of MathCrypt Workshops in order to encourage more mathematicians and computational number theorists to propose and work on hard problems in cryptography. The opportunity to publish intermediate results in venues like MathCrypt should help to de-risk this endeavor and encourage more mathematician to pursue these research directions. In fact, a Program Officer from NSF spoke at the first MathCrypt workshop in August 2018 and encouraged participants to apply to the NSF SaTC program for potential support for their research. [Extracted from the article]