SPIDER: A Faster and Smaller Identity-Based Signature From Isogenies

Tako Boris Fouotsa; Gustave Tchoffo Saah

Paper 2026/2701

SPIDER: A Faster and Smaller Identity-Based Signature From Isogenies

Tako Boris Fouotsa

, University of Manchester

Gustave Tchoffo Saah

, University of Bamenda

Abstract

PRISM is an isogeny-based digital signature whose security relies on the problem of computing large prime degree isogenies from a supersingular elliptic curve of unknown endomorphism ring. In this paper, we design SPIDER, a digital signature that builds on a sigma protocol which when given a supersingular elliptic curve $E$, proves the knowledge of an isogeny $\phi: E\rightarrow E'$ of prime (or non smooth) degree $d$. SPIDER can hence be seen as a proof of knowledge of a PRISM signature. The latter observation allows us to combine SPIDER and PRISM to obtain an Identity-Based Signature (IBS) which we denote by SPIDER-IBS. SPIDER-IBS is the most efficient and the most compact isogeny-based IBS scheme, as all its predecessors are based on isogeny group actions.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Published elsewhere. PQCrypto 2026
DOI: 10.1007/978-3-032-22695-2_14
Keywords: Post-Quantum Cryptography Isogenies Identity-based Signature
Contact author(s): research @ borisfouotsa com
gustavesaah @ gmail com
History: 2026-11-04: approved; 2026-10-30: received; See all versions
Short URL: https://ia.cr/2026/2701
License: CC BY

BibTeX

@misc{cryptoeprint:2026/2701,
      author = {Tako Boris Fouotsa and Gustave Tchoffo Saah},
      title = {{SPIDER}: A Faster and Smaller Identity-Based Signature From Isogenies},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/2701},
      year = {2026},
      doi = {10.1007/978-3-032-22695-2_14},
      url = {https://eprint.iacr.org/2026/2701}
}