Free-riding and whitewashing in peer-to-peer systems

Abstract

-We devise a simple model to study the phenomenon of free-riding and the effect of free identities on user behavior in peer-to-peer systems. At the heart of our model is a strategic user of a certain type, an intrinsic and private parameter that reflects the user's generosity. The user decides whether to contribute or free-ride based on how the current burden of contributing in the system compares to her type. We derive the emerging cooperation level in equilibrium and quantify the effect of providing free-riders with degraded service on the emerging cooperation. We find that this penalty mechanism is beneficial mostly when the "generosity level" of the society (i.e., the average type) is low. To quantify the social cost of free identities, we extend the model to account for dynamic scenarios with turnover (users joining and leaving) and with whitewashers: users who strategically leave the system and re-join with a new identity. We find that the imposition of penalty on all legitimate newcomers incurs a significant social loss only under high turnover rates in conjunction with intermediate societal generosity levels.

Slowing down to speed up: Protecting users against massive attacks in content distribution systems

“…Rewarding users who vote might induce large amounts of indiscriminate votes, since users would attempt to increase the amount of benefits. Punishing users who do not vote, conversely, is susceptible to whitewashing (FELDMAN et al, 2006), although there is a non-negligible cost to obtain a new identity.…”

On incentivizing caching for P2P-VoD systems

“…There have been number of research works on incentive issues for P2P systems, e.g., general framework [24], [16], service differentiation models [13], [9], reputation systems [8], [10], multilateral exchange systems [1] and Shapley value approach [14]. While the earlier works [7], [4], [6] are mainly for file sharing systems, recently some research works have been focusing on P2P streaming/VoD systems, e.g., modified tit-for-tat protocol [15], [17], punishment based [12] and reward based [22] mechanisms were proposed. These works incentivized the peers to upload and serve other peers, however, in a large scale distributed system, it is very hard for the peers to be smart enough to know what are the proper data that they should cache.…”

Performance Evaluation of Personal and General Data Classes for Trust Management in MANETs

“…Otherwise, the packet is forwarded with a probability p 2 . In general, p 1 is high (to let newcomers integrate with the network), while p 2 is low (to discourage network participants from whitewashing behaviour 29) , i.e., changing identity in order to take advantage of the cooperative approach to unknown nodes). The initial period of the existence of the network is specified by a threshold parameter t unkn (time until which the preferential p 1 probability is used).…”