Metering Schemes with Pricing

Abstract

Metering schemes are cryptographic protocols to count the number of visits received by web sites. These measurement systems are used to decide the amount of money to be paid to web sites hosting advertisements. Indeed, the amount of money paid by the publicity agencies to the web sites depends on the number of clients which visited the sites. In this paper we consider a generalization of the metering scheme proposed by Naor and Pinkas [5]. In their scheme a web site is paid if and only if it has been visited by at least a certain number, say h, of clients. In our scheme there are two thresholds, say £ and h, with £ < h. If a web site is visited by at most £ clients then the web site receives no money. If it receives at least h visits then it receives a full payment. Finally, if it receives a number of visits comprised between £ + 1 and h - 1 then it receives a partial payment which depends on /. We provide lower bounds on the size of the information distributed to clients and to servers by metering schemes and present a scheme which achieves these lower bounds.