The overall system consists of the publication system, which is responsible for storing and serving documents; and the communications channel, which is responsible for providing confidential and anonymous communications between parties. This paper focuses on the design of the publication system as a back-end for the communications channel.
The agents in our publication system are the author, the server, and the reader. These agents are layered over the communications channel; currently they communicate with one another via addresses which are implemented as remailer reply blocks [30]. Authors are agents that produce documents and wish to store them in the service, servers are computers which store data for authors, and readers are people who retrieve documents from the service.
Free Haven is based on a community of servers (which as a whole is termed the ``servnet'') where each server hosts data from the other servers in exchange for the opportunity to store its own data in the servnet. The servnet is dynamic: data moves from one server to another every so often, based on each server's trust of the others. Servers transfer data by trading. This means that the only way to introduce a new file into the system is for a server to use (and thus provide) more space on its local system. This new file will migrate to other servers by the process of trading.
Each server has a public key and one (or perhaps more) remailer reply blocks, which together can be used to provide secure, authenticated, pseudonymous communication with that server. Every machine in the servnet has a database which contains the public keys and reply blocks of other nodes in the servnet.
Authors assign an expiration date to documents when they are published; servers make a promise to maintain the availability of a given document until its expiration date is reached. Honest behavior is enforced by other servers losing trust in a server that ``drops'' data. This trust is monitored and updated by use of a trust network. Each server maintains a database containing its trust of the other servers.