Cryptology ePrint Archive: Report 2013/622

Decentralized Anonymous Credentials

Christina Garman and Matthew Green and Ian Miers

Abstract: Anonymous credentials provide a powerful tool for making assertions about identity while maintaining privacy. However, a limitation of today's anonymous credential systems is the need for a trusted credential issuer --- which is both a single point of failure and a target for compromise. Furthermore, the need for such a trusted issuer can make it challenging to deploy credential systems in practice, particularly in the ad hoc network setting (e.g., anonymous peer-to-peer networks) where no single party can be trusted with this responsibility.

In this work we propose a novel anonymous credential scheme that eliminates the need for a trusted credential issuer. Our approach builds on recent results in the area of electronic cash and uses techniques --- such as the calculation of a distributed transaction ledger --- that are currently in widespread deployment in the Bitcoin payment system. Using this decentralized ledger and standard cryptographic primitives, we propose and provide a proof of security for a basic anonymous credential system that allows users to make flexible identity assertions with strong privacy guarantees. Finally, we discuss a number of practical applications for our techniques, including resource management in ad hoc networks and prevention of Sybil attacks. We implement our scheme and measure its efficiency.

Category / Keywords: cryptographic protocols / anonymous credentials, Bitcoin

Date: received 26 Sep 2013, last revised 15 Oct 2013

Contact author: cgarman at cs jhu edu

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Note: Clarifications and corrections

Version: 20131015:180746 (All versions of this report)

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