Practicable Cryptographic Techniques for Secure and Data-efficient Customer Loyalty Systems

In subproject T2 a new privacy-preserving customer loyalty system for the retail sector is being developed and evaluated. In a customer loyalty systems, customers are rewarded for retail purchases, often these systems award a certain number of points for each dollar spent. Compared to existing systems, which are explicitly built to gather user data, the new system will set new standards in terms of security and privacy. It gives customers cryptographic guarantees that their privacy is being preserved, making it so the loyalty system provider does not learn anything about the user or their shopping history. To achieve this goal, cryptographic techniques similar to anonymous credentials are used, which have been developed in subproject C1. They use zero-knowledge proof systems, digital signatures, and pairing-based cryptography. These techniques will be enhanced and optimized for the application in a customer loyalty systems. Once particular challenge is double-spending protection.

Together with Diebold Nixdorf, a service provider for the retail sector, the subproject realizes a prototype system to prove that such systems can be realistically built, to showcase the power of the cryptographic techniques, and to evaluate whether such a system is suited for real-world use. The prototype is implemented using Cryptimeleon for the cryptographic basics.