key: 2025-implementing-Fiat-Shamir
type: unpublished
title: Hooking up with Fiat-Shamir
authors:
  - Ben Smyth
year: 2025
description: >-
  A JavaScript framework for applying the Fiat-Shamir transformation to sigma protocols correctly,
  with proofs of knowledge of a discrete logarithm, of equality between logarithms, and of
  disjunctive equality as worked examples.
keywords: >-
  Fiat-Shamir, zero-knowledge proof, sigma protocol, discrete logarithm, non-malleable ElGamal,
  JavaScript, proven secure by design
abstract: >-
  A zero-knowledge proof convinces us of some claim's validity without revealing specifics. For
  example, you can prove possession of a private key without leaking any information about your key.
  Zero-knowledge proofs are typically derived by application of the Fiat-Shamir transformation to
  sigma protocols. Unfortunately, the transformation is commonly misapplied, introducing security
  vulnerabilities. Herein, I present a JavaScript framework for correct transformation.
links:
  - file: Smyth25-implementing-Fiat-Shamir.pdf
    text: Draft