Security without identification: transaction systems to make big brother obsolete
Communications of the ACM
Digital payment systems enabling security and unobservability
Computers and Security
On blind signatures and perfect crimes
Computers and Security
Untraceable off-line cash in wallet with observers
CRYPTO '93 Proceedings of the 13th annual international cryptology conference on Advances in cryptology
EUROCRYPT '93 Workshop on the theory and application of cryptographic techniques on Advances in cryptology
Revokable and versatile electronic money (extended abstract)
CCS '96 Proceedings of the 3rd ACM conference on Computer and communications security
An efficient fair payment system
CCS '96 Proceedings of the 3rd ACM conference on Computer and communications security
Strong loss tolerance of electronic coin systems
ACM Transactions on Computer Systems (TOCS)
Trustee-based tracing extensions to anonymous cash and the making of anonymous change
Proceedings of the sixth annual ACM-SIAM symposium on Discrete algorithms
Efficient scalable fair cash with off-line extortion prevention
ICICS '97 Proceedings of the First International Conference on Information and Communication Security
Digital Payment Systems with Passive Anonymity-Revoking Trustees
ESORICS '96 Proceedings of the 4th European Symposium on Research in Computer Security: Computer Security
CRYPTO '88 Proceedings of the 8th Annual International Cryptology Conference on Advances in Cryptology
Wallet Databases with Observers
CRYPTO '92 Proceedings of the 12th Annual International Cryptology Conference on Advances in Cryptology
"Indirect Discourse Proof": Achieving Efficient Fair Off-Line E-cash
ASIACRYPT '96 Proceedings of the International Conference on the Theory and Applications of Cryptology and Information Security: Advances in Cryptology
Fair Off-Line e-cash Made Easy
ASIACRYPT '98 Proceedings of the International Conference on the Theory and Applications of Cryptology and Information Security: Advances in Cryptology
Anonymity Control in E-Cash Systems
FC '97 Proceedings of the First International Conference on Financial Cryptography
FC '98 Proceedings of the Second International Conference on Financial Cryptography
A New Offline Privacy Protecting E-cash System with Revokable Anonymity
ISC '02 Proceedings of the 5th International Conference on Information Security
Offline payments with auditable tracing
FC'02 Proceedings of the 6th international conference on Financial cryptography
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Protecting customer privacy is an important requirement when designing electronic cash systems. However, there is also concern that anonymous cash systems can be misused for criminal activities. Particularly blackmailing is in fact more severe in digital cash systems than in paper-based systems. This is because on the one hand the blackmailer is able to avoid physical contact and on the other hand there are no recognizable note numbers. To prevent such activities, several cash systems have been proposed where one or a collection of trustees can revoke the anonymity of a user. However, this also introduces a serious risk that this revocation ability is misused.In this paper we show that the problem of user blackmailing can be solved without this risk. In our proposal, instead of a trustee, it is rather the blackmailed person who reveals the required information to trace extorted coins without compromising any of her secrets. We show how to derive such systems from concrete existing proposals for anonymityrevocable cash systems with passive trustee.