Secure Multi-Coupons for Federated Environments: Privacy-Preserving and Customer-Friendly

Abstract

Abstract.A digital multi-coupon is similar to a paper-based booklet containing k coupons that can be purchased from one vendor and later redeemed at a vendor in exchange for services. Current schemes, offering privacy-protection and strong security properties such as unsplittability of multi-coupons, address business scenarios with a single vendor and multiple customers, and require customers to redeem coupons in some fixed order.In this paper, we propose a multi-coupon scheme for federated environments that preserves the security and privacy properties of existing schemes, as well as their asymptotic communication and computation complexity. We define a generic formal security model and show that our scheme meets the formal requirements of this framework. Moreover, in contrast to previous solutions, we allow customers to redeem their coupons in an arbitrary order.

A Secure Multicoupon Solution for Multi-merchant Scenarios

“…• Multi-merchant. As in the single-merchant scenario many customers can use multicoupons at one merchant, but in this case, in contrast to single-merchant scenario, a customer can use the same multicoupon at different merchants [7]. In this context, a merchant can accept coupons that were issued by another entity (another merchant or an issuer).…”

“…The claim protocol is required when the entity that issues coupons and the entity that changes the coupons to the customer for goods or services are not the same entity. This is the case for a multi-merchant scenario like the proposal in [7]. On the other hand, a refund protocol allows customers to recover from the issuer the value of already issued coupons and not yet used.…”

“…To our best knowledge, previous multicoupon schemes do not deal with this security problem [7]. In our scheme, merchants join or leave an issuing entity without causing a security problem for other merchants, customers and the issuer: customers will be able to spend the remaining coupons of the multicoupon at other merchants.…”

“…On the other hand, strong unsplittability requires that if a customer gives a single coupon to another customer, the first customer cannot use any other coupon until the second customer provides some information to the first one. This makes that customers sharing coupons must trust each other [7]. The property of unsplittability is not always required and it depends on the type of service offered [4].…”

“…With respect to functionalities, all analyzed solutions [1]- [7] provide the basic protocols required for operating with multicoupons (issue and redeem) in single-merchant scenarios. However, more procedures are needed for more general scenarios, such as claim and refund.…”