Decentralized Anonymous Credentials

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 techniquessuch 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.

Zero-Knowledge Proof-of-Identity: Sybil-Resistant, Anonymous Authentication on Permissionless Blockchains and Incentive Compatible, Strictly Dominant Cryptocurrencies

“…This problem is shared with other schemes for pseudoanymization: for example, Bitnym [FWB15] requires that a Trusted Third Party must check the real identity of a user before allowing the creation of a bounded number of valid genesis pseudonyms. Decentralized Anonymous Credentials [GGM13] was first to show how to decentralise the issuance of anonymous credentials and integrate them within a blockchain (i.e., Bitcoin), but they do not re-use previously existing credentials and they still rely on Proof-of-Work for Sybil-resistance. Decentralized Blacklistable Anonymous Credentials with Reputation [YAXY17] introduce blacklistable reputation on blockchains, but users must also publish their real-world identity (i.e., non-anonymous).…”

Application of Public Ledgers to Revocation in Distributed Access Control

“…Documents and other messages can be notarized by publishing a hash of the data in a Bitcoin transaction, which can later be used to prove that the document existed at a specific time. Other applications of the blockchain technology include the Internet name service (Namecoin) and anonymous credentials [10]. Recently, there has been a rush to propose new financial applications from land registry to diamond trade and from energy markets to tax audits [26].…”

Bitcoin Generation using Blockchain Technology

“…Some of the authors told that the blockchain technology is decentralized network [10,11] and it is a ledger of all transactions [12] and linked like a linked list [13]. The transactions are shared by all the participants in the network [14]. Every transaction is secured with public-key cryptography concept [15].…”