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I've done this! You can see them with the naked eye quite easily. Just shine a light diagonally at the surface. I wouldn't bother reading them by hand though.
by batou 11y ago
I've done this! You can see them with the naked eye quite easily. Just shine a light diagonally at the surface. I wouldn't bother reading them by hand though. You could take a photo of it with a digital camera then post-process it and stick it through mathematica or something.
However you might as well just use a card reader.
I used to hack stored value phone cards back in the very early 1990s. First they had an optical system which was easily circumventable with a torch a knife and some epoxy glue. Then there were the smart card ones which were easy to hack by scratching off the programming voltage pad on the card.
I got to the later mag strip cards like this and couldn't be bothered any more.
- deutronium 11y agoNeat :) Yeah I was thinking you could write an algorithm to process the image of the credit card to data. What do you mean by "they had an optical system which was easily circumventable with a torch a knife and some epoxy" out of interest?
- batou 11y agoWell they were pretty crap. There was a metalised bit of plastic for the card and the reader burned certain bits of the plastic to gate the light. If you bought a £5 card you could cut a hole in it, fill it up with epoxy and use a permanent marker to fool it into thinking you had a £20 card :) Edit: my memory is faulty; they were units, not £. Been a long time :)
- davb 11y agoI remember these! A quick Google yields the following, with an example of the reader mechanism http://www.telephonecardcollector.com/optical-cardphone-payphone.htm http://www.telephonecardcollector.com/optical-cardphone-payp... A touch of nostalgia there.
- batou 11y agoThat's the ones! Never seen inside one before - thanks for posting!