As a followup to Tom's bibliography, here's a list I compiled about six months ago on digital cash, including Chaum's basic articles, others published in this area, and a list of relevant U.S. patents. - Tim O. ----------- Bibliography for Digital Cash and Checks using Cryptographic Techniques Articles Chaum, D., Showing credentials without identification: transferring signatures between unconditionally unlinkable pseudonyms. (Springer-Verlag, Berlin, West Germany, p. 246-64, 1990)(Conference: Advances in Cryptology-AUSCRYPT '90 International Conference on Cryptology. Proceedings, Sydney, NSW, Australia, 8-11 Jan. 1990) Chaum, D. den Boer, B. van Heyst, E. Mjolsnes, S. Steenbeek, A., Efficient offline electronic checks. (Springer-Verlag, Berlin, Germany, p. 294-301, 1990)(Conference: Advances in Cryptology - EUROCRYPT '89. Workshop on the Theory and Application of Cryptographic Techniques Proceedings, Houthalen, Belgium, 10-13 April 1989) Chaum, D., Online cash checks. (Springer-Verlag, Berlin, Germany, p. 288-93, 1990)(Conference: Advances in Cryptology - EUROCRYPT '89. Workshop on the Theory and Application of Cryptographic Techniques Proceedings, Houthalen, Belgium, 10-13 April 1989) Chaum, David, Security without Identification: Transaction Systems to make Big Brother Obsolete; Communications of the ACM 28/10 (1985) 1030-1044. Chaum, D. Fiat, A. Naor, M., Untraceable electronic cash. (Springer-Verlag, Berlin, West Germany, p. 319-27, 1990)(Conference: Advances in Cryptology - CRYPTO '88. Proceedings, Santa Barbara, CA, USA, 21-25 Aug. 1988) Okamoto, T. Ohta, K., Disposable zero-knowledge authentications and their applications to untraceable electronic cash. (Springer-Verlag, Berlin, West Germany, p. 481-96, 1990)(Conference: Advances in Cryptology - CRYPTO '89. Proceedings, Santa Barbara, CA, USA, 20-24 Aug. 1989) Even, S., Secure off-line electronic fund transfer between nontrusting parties. (North-Holland, Amsterdam, Netherlands, p. 57-66, 1989)(Conference: Smart Card 2000: The Future of IC Cards. Proceedings of the IFIP WG 11.6 International Conference, Laxenburg, Austria, 19-20 Oct. 1987) Tunstall, J.S., Electronic currency. (North-Holland, Amsterdam, Netherlands, p. 47-8, 1989)(Conference: Smart Card 2000: The Future of IC Cards. Proceedings of the IFIP WG 11.6 International Conference, Laxenburg, Austria, 19-20 Oct. 1987) Hayes, Barry, Anonymous One-Time Signatures and Flexible Untracable Electronic Cash, in AusCrypt '90: A Workshop on Cryptology, Secure Communication and Computer Security, January, 1990. U. S. Patents W. M. Benton, Funds Transfer System using Optically Coupled, Portable Modules, US Pat. #4,454,414, Jun 12, 1984. W. G. Bouricius and P. E. Stuckert, Method and Apparatus for Secure Message Transmission for Use in Electronic Funds Transfer Systems, US Pat. #4,302,810, Nov. 24, 1981. D. Chaum, "Cryptographic Identification, Financial Transaction, and Credential Device," US Pat #4,529,870, Jul. 16, 1985. W. S. Powell, "Information Communicating Apparatus and Method," US Pat. #4,320,387, Mar. 16, 1982. P. E. Stuckert, "Personal Portable Terminal for Financial Transactions," US Pat. #4,277,837, Jul. 7, 1981.