How do I keep my email and passwords secure without full-device encryption? I bought a cheap, no-name Android 4.1.1 tablet a while back, and was dismayed  to find that the "Encrypt Data" option was simply not present in the "Settings" -> "Security" menu.  I then upgraded to a more mainstream Asus Memo Pad HD 7 assuming that this would have the full device encryption option, but this tablet didn't have it either!

So I was wondering if there were any means of keeping e-mails (including ones that were sent unencrypted)/ passwords safe from attackers who have root access in case I lose my device, in the absence of full-disk encryption? Keeping web-browser passwords/ authentication cookies secret would be very handy, too. 

Thanks!
I also own the same device but my tablet shows the encryption option. You're sure you are using stock firmware?