We show how group discounts can be offered without forcing buyers to
surrender their anonymity, as long as buyers can use their own computing
devices (e.g. smartphone, tablet or computer) to perform a purchase.
Specifically, we present a protocol for privacy-preserving group discounts. The
protocol allows a group of buyers to prove how many they are without disclosing
their identities. Coupled with an anonymous payment system, this makes group
discounts compatible with buyer privacy (that is, buyer anonymity).Comment: Presented at 9th DPM International Workshop on Data Privacy
Management (DPM 2014, Sep. 10,2014). To appear in workshop proceedings, LNCS,
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