> I have an aplication that uses authentication (Users and passwords). I have a complain from one of my clients that what ever passwords he made thers one guy he has a small program he uses to review and reveal any passwords entered through the keyboard.
>
> How can I prptect my client and prevent the revealing of the passwords ?

No way.
If the other guy have some sniff program that watch every keystroke and then sent it to him there is NOTHING you could do about it.
But the sysadmin could,. He/She could see what process are running and then KILL that process which seems suspicious and delete the calling application (if he/she could).

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Borislav Borissov

Against Stupidity the Gods themselves Contend in Vain - Johann Christoph Friedrich von Schiller
The only thing normal about database guys is their tables.