# Post-Quantum Revocable Linkable Ring Signature Scheme Based on SPHINCS+ for V2G Scenarios

## TL;DR

This paper introduces a new quantum-resistant signature scheme for Vehicle-to-Grid networks that protects user privacy while ensuring secure and traceable transactions.

## Contribution

A post-quantum revocable linkable ring signature scheme based on SPHINCS+ with stateless design and privacy-preserving revocation.

## Key findings

- The proposed scheme is resistant to quantum attacks and eliminates state management issues in traditional signatures.
- A novel revocation mechanism using KEK-sharding prevents privacy leakage while enabling collaborative decryption.
- The scheme ensures anonymity, unforgeability, and forward secrecy in V2G transactions.

## Abstract

As a core support for the integration of new energy and smart grids, Vehicle-to-Grid (V2G) networks face a core contradiction between user privacy protection and transaction security traceability—a dilemma that is further exacerbated by issues such as the quantum computing vulnerability of traditional cryptography, cumbersome key management in stateful ring signatures, and conflicts between revocation mechanisms and privacy protection. To address these problems, this paper proposes a post-quantum revocable linkable ring signature scheme based on SPHINCS+, with the following core innovations: First, the scheme seamlessly integrates the pure hash-based architecture of SPHINCS+ with a stateless design, incorporating WOTS+, FORS, and XMSS technologies, which inherently resists quantum attacks and eliminates the need to track signature states, thus completely resolving the state management dilemma of traditional stateful schemes; second, the scheme introduces an innovative “real signature + pseudo-signature polynomially indistinguishable” mechanism, and by calibrating the authentication path structure and hash distribution of pseudo-signatures (satisfying the Kolmogorov–Smirnov test with D≤0.05), it ensures signer anonymity and mitigates the potential risk of distinguishable pseudo-signatures; third, the scheme designs a KEK (Key Encryption Key)-sharded collaborative revocation mechanism, encrypting and storing the (I,pk,RID) mapping table in fragmented form, with KEK split into KEK1 (held by the Trusted Authority, TA) and KEK2 (held by the regulatory node), with collaborative decryption by both parties required to locate malicious users, thereby resolving the core conflict of privacy leakage in traditional revocation mechanisms; fourth, the scheme generates forward-secure linkable tags based on one-way private key updates and one-time random factors, ensuring that past transactions cannot be traced even if the current private key is compromised; and fifth, the scheme adopts hash commitments instead of complex cryptographic commitments, simplifying computations while efficiently binding transaction amounts to signers—an approach consistent with the pure hash-based design philosophy of SPHINCS+. Security analysis demonstrates that the scheme satisfies the following six core properties: post-quantum security, unforgeability, anonymity, linkability, unframeability, and forward secrecy, thereby providing technical support for secure and anonymous payments in V2G networks in the quantum era.