IACR News item: 06 October 2014
Sébastien Canard, David Pointcheval, Olivier Sanders, Jacques Traoré
ePrint ReportThe unique proposal, secure in the standard model, appeared recently and is unpractical. As evidence, the authors left the construction of an efficient scheme secure in this model as an open problem.
In this paper, we answer it with the first efficient divisible E-cash system secure in the standard model.
It is based on a new way of building the coins, with a unique and public global tree structure for all the coins. Actually, we propose two constructions: a very efficient one in the random oracle model and a less efficient, but still practical, in the standard model. They both achieve constant time for withdrawing and spending coins, while allowing the bank to quickly detect double-spendings by a simple comparison of the serial numbers of deposited coins to the ones of previously spent coins.
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