How let client store stuff encypted ?

[Andreas <maps(dot)on(at)gmx(dot)net>]

Hi,

I'd like to have som magic that lets a remote client store specific data 
in a way that only I can read it.
The problem is, I can't let the application use a key someone has to 
enter on the other end.
Some stuff should be logged automatically silently and secretly so that 
just the db-administrator (me ;) ) can read it even though others can 
pull backups of the whole db. So permissions don't save the day.

I suppose there might be a way to use some public key functions?


Regards
Andreas