[Resource Topic] 2020/072: Anonymous Tokens with Private Metadata Bit

Welcome to the resource topic for 2020/072

Anonymous Tokens with Private Metadata Bit

Authors: Ben Kreuter, Tancrède Lepoint, Michele Orrù, Mariana Raykova


We present a cryptographic construction for anonymous tokens with private metadata bit, called PMBTokens. This primitive enables an issuer to provide a user with a lightweight, single-use anonymous trust token that can embed a single private bit, which is accessible only to the party who holds the secret authority key and is private with respect to anyone else. Our construction generalizes and extends the functionality of Privacy Pass (PETS’18) with this private metadata bit capability. It is based on the DDH and CTDH assumptions in the random oracle model and provides unforgeability, unlinkability, and privacy for the metadata bit. Both Privacy Pass and PMBTokens rely on non-interactive zero-knowledge proofs (NIZKs). We present new techniques to remove the need for NIZKs, while still achieving unlinkability. We implement our constructions and we report their efficiency costs.

ePrint: https://eprint.iacr.org/2020/072

Talk: https://www.youtube.com/watch?v=uk3WOFaasCQ

Slides: https://iacr.org/submit/files/slides/2020/crypto/crypto2020/145/slides.pdf

See all topics related to this paper.

Feel free to post resources that are related to this paper below.

Example resources include: implementations, explanation materials, talks, slides, links to previous discussions on other websites.

For more information, see the rules for Resource Topics .