I am planning to add some cryptographic properties (file encryption and digital signature on file I/O) to Linux filesystem. In detail, I want that user can do file I/O with encrypted files like he used to do with usual file except some minor changes (e.g. supply key for decrypting file). For digital signature, all read and write acts on file of any user must be signed and recorded so that someone else can give concrete evidences that a user did something on files later on.
At the first glance, I think I should implement new system calls for file I/O with encrypted files and add sign procedure to current file I/O system calls. Since I don't know much about kernel programming, VFS, ext2 or ext3 filesystem then I don't know where I should start. Can anybody give me some hints?
Dang Nguyen Duc