The disclosed technology applies the principle of anonymous reciprocity to facilitate remote backups. A local computer stores other computer's backup files, while storing backup copies of local files on other computers connected through a network. Each computer may securely maintain and manage storage for other computers' files. Application may be constrained to a local area network, or work on the Internet. The disclosed technology works in a peer-to-peer environment; no central server is required. The same disclosed technology may also apply to file sharing.