[Cryptography] Clever physical 2nd-factor authentication

[Adam Sampson]

Jerry Leichter <leichter at lrw.com> writes:

> Basic idea: The user gets a credit card with a transparent window on
> which a user-specific mask - a pattern of lines - is pre-printed.  The
> server sends an image that, when viewed through the mask, forms a
> passcode to be sent back to the server.

That's pretty similar to the Lenslok copy protection system used by a
bunch of games in the early 1980s:
  http://www.birdsanctuary.co.uk/sanct/s_lenslok.php

(Lenslok used a strip of prisms rather than just a mask, but it's
otherwise identical.)

It was generally thought to be a horrible idea at the time, but
presumably it's a bit easier to make it scale properly now...

-- 
Adam Sampson <ats at offog.org>                         <http://offog.org/>