In the past, I've specified a symbol font of some kind for such a password field. I now try to avoid storing passwords in any table in my database due to the increased security risk and the fact that it is rarely necessary to store passwords like this.
Why do you need this table? (Maybe there's a better alternative.)
I want to just experiment to see what i can do with scirpts. So can you please tell me what type of symbol font i need. I want to use this font in other tables also.
On my Windows computer, I have a font installed called "symbol" that works. Any other similar font such as a "wingding" font will work for this. Keep in mind that this meets the function not the appearance requirements of what you have requested. Since you see symbols instead of letters in the field, it can't easily be read by another person peeking at the screen.
An OnObjectKeystroke script trigger could run a script that processes each keystroke character by character, storing the the input character in a hidden field, while inserting the bullet character as a placeholder in the visible field. This takes quite a bit of programming if you still want the back space, delete, arrow, tab, and such keys to also work in this field.
You may want to take a look at the Show Custom Dialog script step. Its input fields can be configured to show only bullets to mark each input character just like a classic password log in dialog.