A method of managing data files in a file caching server provides access to a plurality of stored data files. The method is to receive a request for a file, which is identified by a cryptographically secure checksum. The availability of the file is determined using the cryptographically secure checksum and, if said file is available, retrieving the file. If the file is not available to said file caching server, then a file request is issued to, and the file is retrieved from another file server where the file with the cryptographically secure checksum exists.