WOT for WAT: Spinning the Web of Trust for Peer-to-Peer Barter Relationships


IEICE TRANSACTIONS on Communications   Vol.E88-B    No.4    pp.1503-1510
Publication Date: 2005/04/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.4.1503
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Internet Technology V)
P2P,  PGP,  trust,  currency,  club formation,  

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Peer-to-peer complementary currencies can be powerful tools for promoting collaborations and building relationships on the Internet. i-wat is a proposed such currency based on WAT System, a polycentric complementary currency using WAT tickets as its medium of exchange. Participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-wat implements the tickets electronically by exchanges of messages signed in OpenPGP. This paper clarifies the trust model of i-wat, and investigates how it is related with that of PGP. To implement the model by dynamically building an appropriate web of trust (WOT), we claim that it would suffice if the behaviors of participants satisfy the following three properties:

1. mutual signing by knowing, or any two mutual acquaintances sign the public keys of each other,
2. mutual signing by participation, or the drawer and a user of an i-wat ticket sign the public keys of each other, and
3. mutual full trust by participation, or the drawer and a user of an i-wat ticket fully trust each other, and a recipient fully trust the corresponding user of a ticket, in the context of PGP public key signing.

Likelihood of satisfaction of these properties is supported by the (dis)incentives imposed by the semantics of i-wat. A reference implementation of i-wat has been developed in the form of a Jabber instant messaging client. We are beginning to put the currency system into practical use.