I wrote myself a database that I use for passwords and the like. I get around this by masking text until I tap a button, and then waiting a random number of ticks before decrypting the value and progressively unmasking the text. It takes between ½ and two seconds. The problem I've yet to solve is hiding the text. Leaving it on-screen for, say 10 seconds before re-masking and encrypting is fine for now but sometimes that's not long enough.
The other thing it does is with a tap and waiting for the same random number of ticks is to copy the value to the clipboard so that I can paste it into a browser.
The other thing it does is with a tap and waiting for the same random number of ticks is to copy the value to the clipboard so that I can paste it into a browser.
Not perfect but its a version 1 at least.