Credence is a distributed object reputation management scheme that counteracts content pollution in peer-to-peer filesharing systems.
Credence papers were published in February 2005 by Kevin Walsh and Emin Gün Sirer.

Credence users are served as well as they serve others. Users who don't vote
don't get any voting results. Users giving intentionally bad votes get bad
results themselves. Users sending random votes get random or no results.

How it works

After getting a file, a user of a Credence enabled system is given a chance to submit a single vote. Either a positive (thumbs-up) vote for content matching its description or a negative (thumbs-down) vote for pollution. Votes are cryptographically signed.

Votes of other users are gathered to find like-minded users and users of the direct opposite. When a user asks for votes on a file, the votes of the like-minded are counted as positive and the votes of the opposite are negated.

Attacks

A user attacking Credence system by sending faulty votes would have
to choose a target file and vote correctly on all other files, but the one he or she
is attacking. So the user would be supporting Credence a lot more than hurting
it.

Implementations

simulator used in testing

limewire add-on

External link

Research homepage