Hyperledger Global Forum 2021

Immunity credentials facilitate vaccinated individuals to authenticate their immunity while returning to work or travel, etc. Privacy enabled credentials that do not rely on centralized parties are essential to secure users’ sensitive data. We present a decentralized system that provides verifiable credentials to prove immunity in a privacy preserving manner. Our system provides strong cryptographic guarantees for privacy and verifiability. We leverage a special cryptographic primitive, Content Extraction Signature (BLS Signatures), that enables selective disclosure of immunity claims in a verifiable manner. Immutable record of claims on Blockchain ensures authenticity of claims during the credential verification process. Our solution enables users to reuse the tamper-proof verification status recorded on blockchain ledger without recurrent proof generation and verification process.