When two dynamic magstripe products appear on the front page of HN, I just had to find out how it works.
Protean provided a link on the front page FAQ but unfortunately that link doesn't work, so here's the working how-it-works entry[1] and a history of reprogrammable card technologies[2] from their blog. The "magstripe" is essentially an electromagnet that is able to sense the reader's swipe head and start the "playback" along the entire track. If you'd like to build a simple one, you just need to playback a waveform into a coil placed at the swipe head [3].
And regarding their answer on the card skimming bit, it's most likely just a form of software protection. If they can so easily duplicate a card's magstripe, what's stopping anyone from being able to do it (with their product)?
Protean provided a link on the front page FAQ but unfortunately that link doesn't work, so here's the working how-it-works entry[1] and a history of reprogrammable card technologies[2] from their blog. The "magstripe" is essentially an electromagnet that is able to sense the reader's swipe head and start the "playback" along the entire track. If you'd like to build a simple one, you just need to playback a waveform into a coil placed at the swipe head [3].
And regarding their answer on the card skimming bit, it's most likely just a form of software protection. If they can so easily duplicate a card's magstripe, what's stopping anyone from being able to do it (with their product)?
I would definitely buy one though.
[1] http://blog.getprotean.com/?p=124
[2] http://blog.getprotean.com/?p=396
[3] http://hackaday.com/2008/08/04/magnetic-stripe-card-spoofer/