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Title: VeriSSO: A Privacy-Preserving Legacy-Compatible Single Sign-On Protocol Using Verifiable Credentials
Single Sign-On (SSO) is a popular authentication mechanism enabling a user to access different online services (called Relying Parties, or RPs) with a single login credential obtained from the Identity Provider (IdP). Despite its convenience, SSO schemes represented by the OIDC standard faces significant privacy concerns---the IdP can track users across different RPs; colluding RPs may share data to find linkage of user access. Recent anonymous credential-based SSO solutions provide a promising direction to enhancing user privacy and mitigating IdP single-point failure; however, they fail to support RP authentication, an important security property of the incumbent SSO workflow, and require RPs to perform non-trivial cryptographic verification. This paper introduces VeriSSO, a novel privacy-preserving SSO protocol based on verifiable credentials (VC) that supports RP authentication and is fully compatible with the incumbent SSO workflow. The key intuition is to employ a committee of independent authentication servers (i) to bind RP authentication to VC-based user verification and (ii) to issue identity tokens in a threshold manner, which crucially ensures RP authentication and user unlinkability without IdP involvement or reliance on a trusted central party. Our scheme allows RPs to continue using their existing signature-based identity token verification routine and supports lawful de-anonymization, providing user accountability for misbehavior. Our experiment shows the feasibility and efficiency and VeriSSO, with one SSO workflow completed within 30 milliseconds.  more » « less
Award ID(s):
2247561 2433905 2442382
PAR ID:
10675447
Author(s) / Creator(s):
; ;
Publisher / Repository:
Cryptology ePrint Archive
Date Published:
Subject(s) / Keyword(s):
Single Sign-On, OpenID Connect, Privacy, Authentication, Verifiable Credentials
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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