1. A method comprising: receiving a designation of a file system; representing the file system according to an authenticated data structure including a tree structure, wherein the authenticated data structure comprises a first authentication level comprising a file block-level message authentication code and a second authentication level comprising a file block-level version data structure; representing files of the file system as leaf nodes in a first subtree of the first tree structure, wherein each leaf node serves as a root node of an attached file-version tree; representing directories of the file system as non-leaf nodes in the first subtree of the first tree structure; and representing a free list as a second subtree of the tree structure of the authenticated data structure comprising a list of pointers to respective subtrees of removed blocks of the tree structure.