SD-BLS: Privacy Preserving Selective Disclosure of Verifiable Credentials with Unlinkable Threshold Revocation

TL;DR

This paper introduces SD-BLS, a privacy-preserving digital credential system that enables selective disclosure and efficient revocation checks, protecting user privacy and resisting issuer corruption.

Contribution

It presents a novel approach combining BLS signatures, PVSS, and optimized data structures for fast, privacy-preserving credential revocation and selective disclosure.

Findings

Fast revocation checks with large lists

Robust protection against issuer corruption

Supports selective credential disclosure

Abstract

Ensuring privacy and protection from issuer corruption in digital identity systems is crucial. We propose a method for selective disclosure and privacy-preserving revocation of digital credentials using second-order Elliptic Curves and Boneh-Lynn-Shacham (BLS) signatures. We make holders able to present proofs of possession of selected credentials without disclosing them, and we protect their presentations from replay attacks. Revocations may be distributed among multiple revocation issuers using publicly verifiable secret sharing (PVSS) and activated only by configurable consensus, ensuring robust protection against issuer corruption. Our system's unique design enables extremely fast revocation checks, even with large revocation lists, leveraging optimized hash map lookups.