Framework for privacy preserving credential issuance and verification system using soulbound token

Abstract

This paper proposes a framework for privacy-preserving credential issuance and verification over the public blockchain. The credential used in this framework is a soulbound token (SBT), a non-transferrable non-fungible token (NFT) verifiable on the blockchain. Once the issuing organization issues the credential, this framework gives the holder complete control of the credential. This privacy-preserving property allows the holder to selectively disclose the credential attributes in the verification process. The framework proposed suggests a decentralized credential recovery mechanism if the credential holder loses their private key. This paper compares this framework’s efficiency with different schemes based on privacy-preserving, selective disclosure, and decentralized credential recovery. This paper also compares the overhead for credential issuance and verification with Merkle trees. This paper also discusses the real-world use cases where this framework can be applied.