RSA Laboratories

X-cash: Executable Digital Cash

Markus Jakobsson and Ari Juels

Citation: X-cash: Executable Digital Cash. In Rafael Hirschfeld, editor, Proceedings of Financial Cryptography '98, pages 16-27, Springer-Verlag, 1998. LNCS No. 1465.

Abstract: In this paper, we propose a new financial instrument known as executable digital cash, or X-cash. X-cash is a means of binding an offer to the accompanying goods or payment, enabling the processes of searching and paying to be unified. The result is a mechanism by which electronic trades can occur in a highly distributed setting with strong security guarantees. When a party receives an X-cash offer, he or she can verify that it is bona fide and can initiate a trade immediately, without contacting the originator directly. X-cash may therefore be used, among other things, to enable mobile agents to carry funds and make payments on-site without running the risk of "pick-pocketing". In this paper, we introduce X-cash, describe some variants, and sketch proofs of its security properties.

Note: The ideas in this paper can be extended to enable the creation of highly flexible financial instruments that need not be carried by mobile agents. This idea is treated briefly in this presentation.

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