Efficient methodology for implementation of Encrypted File System in User Space

Abstract: The Encrypted File System (EFS) pushes encryption services into the file system itself. EFS supports secure storage at the system level through a standard UNIX file system interface to encrypted files. User can associate a cryptographic key with the directories they wish to protect. Files in these directories (as well as their pathname components) are transparently encrypted and decrypted with the specified key without further user intervention; clear text is never stored on a disk or sent to a remote file server. EFS can use any available file system for its underlying storage without modifications, including remote file servers such as NFS. System management functions, such as file backup, work in a normal manner and without knowledge of the key. Performance is an important factor to users since encryption can be time consuming. This paper describes the design and implementation of EFS in user space using faster cryptographic algorithms on UNIX Operating system. Implementing EFS in user space makes it portable and flexible; Kernel size will also not increase resulting in more reliable & efficient Operating System. Encryption techniques for file system level encryption are described, and general issues of cryptographic system interfaces to support routine secure computing are discussed.