Privacy-Preserving Authentication for Unlinkable Avatars in the Metaverse

The metaverse is a virtual world that mirrors real life, allowing users to engage in activities and access services without the constraints of time and space. In the metaverse, users can create one or more avatars that reflect their personal preferences, enabling them to participate in activities that match their tastes and needs. To protect users’ freedom and anonymity, it is imperative for metaverse platforms to support the creation of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">unlinkable</i> avatars. This ensures that the different avatars a user creates cannot be connected, keeping their virtual identities separate and reducing the risk of retaliation for their actions. In this paper, we propose an unlinkable avatar authentication scheme, UAVA, which leverages cryptographic group signatures to enable metaverse users to create and certify their avatars without interaction with service providers. These certified avatars can then be anonymously authenticated, ensuring unlinkability between multiple avatars belonging to the same user. UAVA maintains anonymity between users and their avatars, while allowing service providers to trace malicious avatars back to their users. We formally define and prove the security properties of UAVA, and implement the protocol using socket programming, and report on its cryptographic overheads. We also evaluate its cryptographic overhead and compare it to related protocols in terms of efficiency, security, and scalability.