How desperate are you?
If you're not desperate enough to try anything, anything to get it to work, don't read on. This will not be nice. OK? OK.
The trick is to make the web app think that it's not a password box. In other words, don't use TextMode="password"
.
Then in Page_Load
, put txt_punch.Attributes["type"] = "password"
That's it. The browser will know it's a password field (and show asterisks or dots), but the server side won't know, so it will send the content to the client as it it were plain text. Of course, this will also put the password in the page source...