Crowds

TLDR

Crowds groups users into a large, geographically diverse crowd that collectively issues requests on behalf of its members. The paper introduces Crowds, a system for protecting users' anonymity on the world‑wide web. Crowds routes requests through a geographically diverse crowd so that any member could be the source, and the authors present its design, implementation, performance, scalability, and a degrees‑of‑anonymity security analysis.

Abstract

In this paper we introduce a system called Crowds for protecting users' anonymity on the world-wide-web. Crowds, named for the notion of “blending into a crowd,” operates by grouping users into a large and geographically diverse group (crowd) that collectively issues requests on behalf of its members. Web servers are unable to learn the true source of a request because it is equally likely to have originated from any member of the crowd, and even collaborating crowd members cannot distinguish the originator of a request from a member who is merely forwarding the request on behalf of another. We describe the design, implementation, security, performance, and scalability of our system. Our security analysis introduces degrees of anonymity as an important tool for describing and proving anonymity properties.