Modifying files while retaining file modification times

[Lee Phillips]

I want to do something to a file, say encrypt it, without changing its
modification time.  I suppose I can write a script to get the time
from ls, do the modification, then restore the time (after converting
it to numerical format) with /usr/5bin/touch, but I'm hoping that
there is an easier way.  How about it?  (Csh solutions preferred.)
--
                                           Lee Phillips
                                           phillips at fozzie.nrl.navy.mil
                                           phillips at cmf.nrl.navy.mil
                                           phillips at lcp.nrl.navy.mil