TITLE:
A Verifiable Credentials System with Privacy-Preserving Based on Blockchain
AUTHORS:
Zhiji Li
KEYWORDS:
Verifiable Credential, Aggregate Signatures, Privacy Protection, Selective Disclosure, Blockchain
JOURNAL NAME:
Journal of Information Security,
Vol.13 No.2,
February
28,
2022
ABSTRACT: Decentralized identity authentication is generally based on blockchain,
with the protection of user privacy as the core appeal. But traditional
decentralized credential system requires users to show all the information of
the entire credential to the verifier, resulting in unnecessary overexposure of
personal information. From the perspective of user privacy, this paper proposed
a verifiable credential scheme with selective disclosure based on BLS (Bohen- Lynn-Shacham) aggregate
signature. Instead of signing the credentials, we sign the claims in the
credentials. When the user needs to present the credential to verifier, the
user can select a part of but not all claims to be presented. To reduce the
number of signatures of claims after selective disclosure, BLS aggregate
signature is achieved to aggregate signatures of claims into one signature. In
addition, our scheme also supports the aggregation of credentials from
different users. As a result, verifier only needs to verify one signature in
the credential to achieve the purpose of batch verification of credentials. We
analyze the security of our aggregate signature scheme, which can effectively
resist aggregate signature forgery attack and credential theft attack. The
simulation results show that our selective disclosure scheme based on BLS
aggregate signature is acceptable in terms of verification efficiency, and can
reduce the storage cost and communication overhead. As a result, our scheme is
suitable for blockchain, which is strict on bandwidth and storage overhead.