Isogeny-based cryptography is cryptographic schemes whose security is based on the
hardness of a mathematical problem called the isogeny problem, and is attracting attention …

In this paper, we describe an algorithm to compute chains of (2, 2)-isogenies between
products of elliptic curves in the theta model. The description of the algorithm is split into …

The Deuring correspondence is a correspondence between supersingular elliptic curves
and quaternion orders. Under this correspondence, an isogeny between elliptic curves …

We consider the problem of sampling random supersingular elliptic curves over finite fields
of cryptographic size (SRS problem). The currently best-known method combines the …

SQIsign is a well-known post-quantum signature scheme due to its small combined
signature and public-key size. However, SQIsign suffers from notably long signing times …

We present an unconditional CRT algorithm to compute the modular polynomial\(\Phi _\ell
(X, Y)\) in quasi-linear time. The main ingredients of our algorithm are: the embedding …

We present a key recovery attack on SQIsign2D-East that reduces its security level from
$\lambda $ to $\lambda/2$. We exploit the fact that each signature leaks a Legendre symbol …

We introduce SQIPrime, a post-quantum digital signature scheme based on the Deuring
correspondence and Kani's Lemma. Compared to its predecessors that are SQISign and …

We construct two efficient post-quantum ring signatures with anonymity against full key
exposure from isogenies, addressing the limitations of existing isogeny-based ring …

Abstract The Supersingular Isogeny Diffie-Hellman (SIDH) scheme is a public key
cryptosystem that was submitted to the National Institute of Standards and Technology's …