Security and Privacy Applied Research Lab

Conditional E-Payments

Marina Blanton
University of Notre Dame


Conditional e-cash or conditional e-payments have been introduced by Shi et al. (2007) as the means for enabling electronic payments to be based on the outcome of a certain condition not known in advance. In this framework, a payer obtains an electronic coin and can transfer it to a payee under a certain condition. Once the outcome of the condition is known, if it was favorable to the payee, the payee can deposit the coin; otherwise, the payer keeps the money. We show how a solution based on Camenisch-Lysyanskaya signatures with protocols can be built to permit conditional e-payments that outperforms the original scheme in several respects. Furthermore, we extend the scheme to permit payees to further transfer (conditional) payments to other payees addressing the double-spending problem for all participants.


Marina Blanton is an Assistant Professor in the Department of Computer Science and Engineering at the University of Notre Dame. She received her Ph.D. in CS from Purdue University in 2007, MS in CS from Purdue University in 2004, and MS in EECS from Ohio University in 2002. Dr. Blanton's research interests lie in information security, privacy, and applied cryptography. She has over 20 research publications, is a co-editor of a book, and has been actively involved in professional service.