Protecting privacy in e-cash schemes by securing hidden identity approaches against statistical attacks.

Purpose - To enhance security and privacy of e-cash systems that apply revocable anonymity by presenting a statistical attack that reveals the hidden ID and suitable protection means against this kind of attack. Design/methodology/approach - The feasibility of a statistical attack that reveals the ID of user of e-cash schemes with revocable anonymity is shown. To avoid such attacks the application of modulo operations while constructing e-cash coins is proposed. Measurement results are used to back up the suitability of this approach. Findings - Revocable anonymity systems can successfully be attacked. Applying modulo operations can prevent such attacks. Practical implications - The recommendations given in this paper should be applied whenever an e-cash scheme or similar system with revocable anonymity is designed. Otherwise the promised feature may be compromised very easily. Originality/value - The paper identifies a formerly unknown attack against systems with revocable identities, and presents a mathematical solution to protect such systems against the attack presented. [ABSTRACT FROM AUTHOR]