Experiences in Developing a Micro-payment System for Peer-to-Peer Networks

Introduction

A trend towards widespread use of peer to peer systems became eminent over the past years for various content sharing including files, music, videos, etc. These systems suffer from a common problem of individual rationality among peers (Shneidman & Parkes, 2003). This dilemma is also known as the “free-rider” problem. Peers become so self-absorbed that they intend to only download files rather than sharing some files for other peers. Thus they exploit the peer-to-peer system for their own needs but do not contribute anything back for others.

Some content sharing systems provide a “credit” system encouraging or enforcing my equitable use of the system i.e. some form of balancing downloading with a degree of uploading or providing content to share. As downloads and content shares are very high volume, low cost transactions, a micro-payment model may well be very suitable. However most current file sharing systems have not integrated a micro-payment approach. Most existing micro-payment systems implement a customer/vendor relationship which is suitable for client server and retail web applications but not for a P2P environment. These systems (Glassman et al., 1995; Hauser et al., 1996; Anderson et al., 1996; Pedersen, 1996; Liebau et al., 2006; Zghaibeh & Harmantzis, 2006; Vishnumurthy et al., 2003; Garcia & Hoepman, 2005) suffer from online processing and impose scalability and security issues on users.

We present our novel P2P-Netpay micro-payment model and its architecture. P2P-Netpay provides an offline micro-payment model that utilizes a light-weight hashing-based encryption approach. A “peer user” buys e-coins from a broker using macro-payment approach. These coins are stored in the peer’s “e-wallet” stored on the peer’s machine. The peer user pays for content as they download it by transparently passing e-coins to a “peer vendor”. The peer vendor redeems their e-coins with the broker for coins of their own to do P2P downloads. E-coin information can be transparently exchanged between peer vendors when peer users download content from another peer vendor.

We give an overview of the current micro-payment schemes so far attempted for P2P networks. We describe our research methodology of assessing key requirements of content sharing application end users of micro-payment with non-micro-payment approaches. We describe main aspects of the software architecture and design for P2P-Netpay. We describe three different evaluations we have performed on our P2P-Netpay prototype to compare micro-payment versus non-micro-payment usability, performance and heuristic assessment. We conclude with an outline of our further plans for research and development in this area.