c# - Input field which is not visible to user -

i load asp.net page, receive user input , base on action. problem don't want let user see he/she typing , input should not visible well. want process postback if length of input of length 6.

closest can textbox backgroud-color:transparent , no border. autopostback enabled. textbox gets focus, when user presses enter, postback called, text lenght checked , stuff in code behind. unfortunately user can see text he/she types , enter has pressed.

any ideas how can achieve this?

//for of wonder why want this:

page loaded, user sees empty page. she/he put rfid card on rfid reader. reader sends input + enter (should easy setup on reader itself) page. postback appears, length checked, information written on page. not want user see (text textbox especially) before postback. don't have reader , way how hide input need test it. if figure out how postback without sending enter better.

in asp.net there 'visible' property, may disable input. maybe give try.

you set text color same background color (transparent) - worth try.

i set html5 password attribute on input field. user see input, not characters typed.