I’ve been following “Square” it’s a MEGA VC’ed company that has a dongle that accepts credit cards on devices like iPhones. It seems there is some type of dispute over who invented or something…

Square, a new company that makes a small device to let anyone make a credit card payment from their mobile phone, has probably stirred up more excitement than any other startup launching in recent months. But Bob Morley, an associate professor of electrical engineering at Washington University in St. Louis, says there’s a big hitch: He built Square’s credit card reading technology and has filed a patent for it, so the San Francisco company doesn’t own a key part of its tech. He came up with the concept, designed it, and assembled the first working prototype for it, he says.

I’m not really interested in that, so here’s the patent (maybe, it could just be an older one) if you want to check it out…

A method and apparatus are disclosed for determining the remanent noise in a magnetic medium by, for example, dc saturation of a region thereof and measurement of the remaining dc magnetization. A conventional magnetic recording transducer may be used to determine the remanent noise. Upon determination, the remanent noise may then be digitized and stored on the same magnetic medium, in a database, or both to thereby “fingerprint” the magnetic medium. This “fingerprint” may then be later used to verify and authenticate the magnetic medium as being an original. The magnetic medium may be of a type adapted to record information magnetically or, even more broadly, any magnetic surface or substance that can be sensed through its magnetic field. In such manner, any magnetic medium, or any object having an associated magnetic medium, may be “fingerprinted” including credit cards, computer program diskettes, magneto-optic discs, videotapes, cassette tapes, bank checks, stock certificates, etc. A different or additional portion of the magnetic medium can be selected each time the medium is authenticated. In this manner, different fingerprint data can be used for each authentication procedure for added security, and to avoid the ramifications of possible counterfeiting, on-line interception, electronic eavesdropping, or sharing of access data by unscrupulous users.

I haven’t looked through all of it yet, but someone might want to see what you could make… you can also make your own magstripe reader in MAKE too!