Constructing a time structure(linked to directory structure)

[meetkaustubhghosh at vsnl.net]

   I am trying to construct a time structure which will be linked to the directory
structure in the file system.I try to clarify.The structure will store the date of
modifications of a file.The main reason is to get better security.Let us consider a
situation where a employee is to complete a report within a date .He didnot send it
,but later he just shifts the system date backwords,saves the file in the backward
date and shows that he has completed the job in time.But the root user now with this
time structure can look up as the dates of modification of the file.Since every mod.
date is saved he can figure out whether the system date was shifted or not and take
steps accordingly.Can I get any help on this,that is any ideas how this can be
implemented?Please send any suggestions you may think of.The filesystem I am
considering is ext2fs.Thanks in advance for any help.
                                                 Kaustubh Ghosh.