Hello List !
For the "connect from untrusted computers" there are one-time-passwords. I've used libpam-opie in the past with great success for the occasional connection from internet cafe's for example.
By googling, I found this web page: http://andrewho.co.uk/weblog/securing-authentication-in-debain-with-opie Accordingly smart phone can be used to get the One Time Password. Jerome