The present invention provides a method and system of manipulating the original content of at least one original read-only computer file in a computer file-system in a computer system, where the computer system includes an operating system including a framework for in-line monitoring of accesses to the file-system. In an exemplary embodiment, the method, system, and service include (1) transforming the original content via a non-length-preserving data transformation algorithm, thereby resulting in transformed content, (2) storing the transformed content in a transformed computer file, (3) splitting the transformed computer file into a first file (F13 1) and a second file (F—2), and (4) associating the first file (F—1) with the second file (F—2) in the file-system. In an exemplary embodiment, the non-length-preserving data transformation algorithm includes a length-increasing data transformation algorithm (i.e., encryption).