US Patent 8478799 Namespace file system accessing an object store

Method and apparatus for providing a digitally signed file system wherein a namespace file system accesses an object store in which data, metadata and files are objects, each object having a globally unique and content-derived fingerprint and wherein object references are mapped by the fingerprints; the file system has a root object comprising a mapping of all object fingerprints in the file system, such that a change to the file system results in a change in the root object, and tracking changes in the root object provides a history of file system activity.