Paper 2024/2066

COCO: Coconuts and Oblivious Computations for Orthogonal Authentication

Abstract

Authentication often bridges real-world individuals and their virtual public identities, like usernames, user IDs and e-mails, exposing vulnerabilities that threaten user privacy. This research introduces COCO (Coconuts and Oblivious Computations for Orthogonal Authentication), a framework that segregates roles among Verifiers, Authenticators, and Clients to achieve privacy-preserving authentication. COCO eliminates the need for Authenticators to directly access virtual public identifiers or real-world identifiers for authentication. Instead, the framework leverages Oblivious Pseudorandom Functions (OPRFs) and an extended Coconut Credential Scheme to ensure privacy by introducing separate unlinkable orthogonal authentication identifiers and a full-consensus mechanism to perform zero-knowledge authentications whose proof-s are unlinkable across multiple sessions. Authentication process becomes self-contained, preventing definitive reverse tracing of virtual public identifiers to real-world identifiers.

Note: This research introduces COCO (Coconuts and Oblivious Computations for Orthogonal Authentication), a foundational work for a privacy-preserving, full-consensus, zero-knowledge authentication protocol. The protocol demonstrates an approach emphasizing scalability, efficiency, and privacy. We acknowledge the current limitations, such as lack of fault-tolerant mechanisms and many more, and are considerate of areas for future improvements.