Composable and Modular Anonymous Credentials: Definitions and Practical Constructions

Jan Camenisch, Maria Dubovitskaya, Kristiyan Haralambiev, Markulf Kohlweiss

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

It takes time for theoretical advances to get used in practical schemes. Anonymous credential schemes are no exception. For instance, existing schemes suited for real-world use lack formal, composable definitions, partly because they do not support straight-line extraction and rely on random oracles for their security arguments. To address this gap, we propose unlinkable redactable signatures (URS), a new building block for privacy-enhancing protocols, which we use to construct the first efficient UC-secure anonymous credential system that supports multiple issuers, selective disclosure of attributes, and pseudonyms. Our scheme is one of the first such systems for which both the size of a credential and its presentation proof are independent of the number of attributes issued in a credential. Moreover, our new credential scheme does not rely on random oracles. As an important intermediary step, we address the problem of building a functionality for a complex credential system that can cover many different features. Namely, we design a core building block for a single issuer that supports credential issuance and presentation with respect to pseudonyms and then show how to construct a full-fledged credential system with multiple issuers in a modular way. We expect this definitional approach to be of independent interest.
Original languageEnglish
Title of host publicationAdvances in Cryptology - ASIACRYPT 2015 - 21st International Conference on the Theory and Application of Cryptology and Information Security, Auckland, New Zealand, November 29 - December 3, 2015, Proceedings, Part II
Pages262-288
Number of pages27
ISBN (Electronic)978-3-662-48800-3
DOIs
Publication statusE-pub ahead of print - 30 Dec 2015
Event21st Annual International Conference on the Theory and Application of Cryptology and Information Security - University of Auckland, Auckland, New Zealand
Duration: 29 Nov 20153 Dec 2015
https://www.math.auckland.ac.nz/~sgal018/AC2015/index.html

Conference

Conference21st Annual International Conference on the Theory and Application of Cryptology and Information Security
Abbreviated titleAsiacrypt 2015
CountryNew Zealand
CityAuckland
Period29/11/153/12/15
Internet address

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