Paper 2025/1368 Original: eprint.iacr.org/2025/1368 ↗

Post-Quantum Readiness in EdDSA Chains

Abstract

Quantum computers pose a critical threat to blockchains that rely on ECDSA, such as Bitcoin and Ethereum, due to public key exposure and lack of post-quantum protections. Existing proposals for migrating to quantum-secure signatures, including hybrid constructions and zero knowledge key updates, often require address changes or fail to secure inactive accounts. In this work, we show that EdDSA-based blockchains like Sui, Solana, Near, and others offer a structural advantage: their keys are deterministically derived from a seed according to RFC 8032, allowing users to prove ownership through zero knowledge without revealing elliptic curve secrets or changing addresses. Our core contribution is a post-quantum secure protocol that uses the EdDSA seed as a witness in a zero knowledge proof to authorize new quantum-safe signatures. This construction supports seamless migration, even for users with publicly exposed keys, and preserves backward compatibility. We formalize a security model for post quantum ready signatures defined to support dual-mode security and backward compatibility and then we prove the security of our core construction via a game-based argument. Finally, we provide an implementation to validate the feasibility of our approach. Our proof of concept implementation shows a practical system and enables a seamless transition, with current benchmarks showing a proving time of $6.2$ seconds, a verification time of $2.3$ seconds, and a proof size of $5.4$ MB using the Ligetron zkVM.