1. A method of using a computer to generate a security token for a client of a reputation system, comprising: receiving a registration request from the client of the reputation system; observing metadata about the client; selecting observed metadata about the client for use in a security token, wherein the selected metadata comprise metadata that can be correlated through independent observation of the client; generating the security token for the client, the security token derived from the selected metadata; and providing the security token to the client, wherein the client is adapted to use the security token to authenticate the client.