On the Anonymity of Fair Offline E-cash Systems
- Matthieu GaudAffiliated withFrance Télécom R&D
- , Jacques TraoréAffiliated withFrance Télécom R&D
Fair off-line electronic cash (FOLC) schemes [5, 29] have been introduced for preventing misuse of anonymous payment systems by criminals. In these schemes, the anonymity of suspicious transactions can be revoked by a trusted authority.
One of the most efficient FOLC system has been proposed by de Solages and Traoré  at Financial Cryptography’98. Unfortunately, in their scheme, the security for legitimate users (i.e., anonymity) is not clearly established (i.e., based on a standard assumption).
At Asiacrypt’98, Frankel, Tsiounis and Yung  improved the security of  by proposing a fair cash scheme for which they prove anonymity under the Decision Diffie-Hellman (DDH) assumption.
In this paper, we show that Frankel et al. failed to prove that their scheme satisfies the anonymity property. We focus here on this security problem and investigate the relationships between different notions of indistinguishability in the context of fair electronic cash. As a result, we prove under the DDH assumption, that a straightforward variant of , which is more simple and efficient than , is secure for users. This proof relies on the subsequent result of Handschuh, Tsiounis and Yung  showing equivalences between general decision and matching problems. Our proof is somewhat generic and can be used to prove that  is secure as well.
- On the Anonymity of Fair Offline E-cash Systems
- Book Title
- Financial Cryptography
- Book Subtitle
- 7th International Conference, FC 2003, Guadeloupe, French West Indies, January 27-30, 2003. Revised Papers
- pp 34-50
- Print ISBN
- Online ISBN
- Series Title
- Lecture Notes in Computer Science
- Series Volume
- Series ISSN
- Springer Berlin Heidelberg
- Copyright Holder
- Springer-Verlag Berlin Heidelberg
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