Porting the Pay with a (Group) Selfie (PGS) Payment System to Crypto Currency

Abstract

Pay with a (Group) Selfie (PGS) is a novel payment system developed at Khalifa University in the UAE, and currently under test at the Institut de Mathématiques et Science Physique (IMSP) in Benin. The PGS system uses a group selfie to gather all information items needed to encode a purchase: the seller, the buyer, the service/product and the agreed price. Using Visual Cryptography (VC), the photo is then “digitally ripped” into two shares, one for the buyer and one for the seller. In the current version of PGS, these shares are eventually and independently sent to a Bank that cooperates to offer the digital payment service to population living in rural areas. When the purchases of a buyer at a given seller pass a pre-set threshold, the Bank executes a traditional fund transfer between the two. This way, PGS spreads the Bank’s transfer fee over multiple purchases, decreasing the financial cost of each purchase. This paper discusses the challenges of transparently coupling the PGS payment system with digital wallets holding a crypto currency, bringing the financial cost of each purchase to zero.