Music2Share—Copyright-Compliant Music Sharing in P2P Systems TON KALKER, FELLOW, IEEE, DICK H. J. EPEMA, PIETER H. HARTEL, R. (INALD) L. LAGENDIJK, AND MAARTEN VAN STEEN Invited Paper Peer-to-peer (P2P) networks are generally considered to be free havens for pirated content, in particular with respect to music. We describe a solution for the problem of copyright infringement in P2P networks for music sharing. In particular, we propose a P2P protocol that integrates the functions of identification, tracking, and sharing of music with those of licensing, monitoring, and payment. This highly decentralized music-aware P2P protocol will allow ac- cess to large amounts of music of guaranteed quality; it merges in a natural way the policing functions for copyright protection and an efficient music-management infrastructure for the benefit of the user. Keywords—Content-aware networks, digital rights management (DRM), fingerprinting, multimedia, music sharing, peer-to-peer (P2P), search protocols, watermarking. I. INTRODUCTION While the music-recording industry is struggling to fight music-sharing technology such as provided by KaZaa [1] with legal as well as technological means [2], huge numbers of Internet users are turning to music-sharing applications based on peer-to-peer (P2P) technology [3]. However, the concept of legal music sharing embedded in an acceptably Manuscript received September 7, 2003; revised December 28, 2003. T. Kalker is with Philips Research Eindhoven, Eindhoven 5656 AA, The Netherlands, and also with the Technical University Eindhoven, Eindhoven 5612 AZ, The Netherlands (e-mail: ton.kalker@ieee.org). D. H. J. Epema is with the Parallel and Distributed Systems Group, Faculty of Electrical Engineering, Mathematics, and Computer Science, Delft University of Technology, Delft 2600 GA, The Netherlands (e-mail: D.H.J.Epema@ewi.tudelft.nl). P. H. Hartel is with the Distributed and Embedded Systems Group, De- partment of Computer Science, University of Twente, Enschede 7500 AE, The Netherlands (e-mail: pieter.hartel@utwente.nl). R. I. Lagendijk is with the Information and Communication Theory Group, Faculty of Electrical Engineering, Mathematics, and Computer Science (EEMCS), Delft University of Technology, Delft 2628 CD, The Netherlands (e-mail: R.L.Lagendijk@ewi.tudelft.nl). M. van Steen is with the Department of Computer Science, Vrije Univer- siteit, Amsterdam 1081 HV, The Netherlands (e-mail: steen@cs.vu.nl). Digital Object Identifier 10.1109/JPROC.2004.827368 secure P2P framework has barely been put to the test. In this paper we propose an architecture called Music2Share (M2S) in which secure content sharing and P2P networking coexist. A number of explanations have been offered for the success of (illegal) music sharing over the Internet. First, it is supposedly due to the for-free access to digitally perfectly copied yet pirated content, the underlying argument being that many consumers feel that the price of prepressed music is too high. Second, the choice of music on the major P2P networks is almost unlimited, certainly in comparison to what is offered by regular retail shops. Third, there is a trend that consumers are no longer interested in complete CD albums, but only in particular tracks. Why would users buy CDs if P2P networks allow them to collect any tracks of their interest and compile their own CDs? Fourth, the number of households with fast connections to the Internet, which makes downloading (and uploading) music more convenient, is increasing rapidly. Consequently, digital networks in general and P2P net- works in particular are indeed currently operating as free havens for pirated content, in particular, music. However, the current success of illegal music distribution over the Internet does in itself not provide evidence that commercial, copy- right-compliant online music selling and sharing is and will remain unfeasible. First evidence is provided by iTunes [4] from Apple, a central-server based system that offers a rele- vant collection of music for the price (at the time of writing) of US$0.99 per track. The popularity of iTunes shows that users are willing to pay for content if the online music ser- vice is sufficiently compelling (with respect to music quality, ease of use, and availability of relevant music). Central-server based systems for electronic music delivery have the distinct disadvantage of a bandwidth bottleneck at the central server(s). In such systems, two users who live in close proximity (in cyberspace) and are buying the same track still need to download from this central server, whereas they could more easily have shared the same track via a local 0018-9219/04$20.00 © 2004 IEEE PROCEEDINGS OF THE IEEE, VOL. 92, NO. 6, JUNE 2004 961