An Untraceable Credential Revocation Approach Based on a Novel Merkle Tree Accumulator

As digital identity gains increasing importance, current centralized digital identity systems face significant limitations. Recent years have seen a shift towards decentralized and self-sovereign identity models, underpinned by verifiable credentials and cryptographic signatures. A critical challenge in these systems is credential revocation, presenting unique issues absent in centralized systems. In this context, blockchain (BC) systems offer a viable support for implementing revocation mechanisms without compromising the advantages of decentralized identity. However, they introduce storage and cost challenges. This work proposes a credential revocation approach utilizing a Merkle tree-based accumulator. Our accumulator enables a trade-off between anonymity and proof complexity, offers resistance to credential tracking, and relies solely on hash function collision resistance, making it quantum-safe. Additionally, we have integrated the accumulator within a broader identity management library and reported its performance on standard hardware.