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Yay, hiss! Cards’ mag stripe ‘fingerprint’ may foil thieves

Jay MacDonald

Recently I was kickin’ back with a younger buddy who was unaware that we were listening to an old-school mixtape I’d cobbled together back in the misty days of LPs. When one song track began with several seconds of unmistakable revolving static hiss, his eyebrows shot up.

“Is that vinyl?!” he whispered. Yes, grasshopper, I replied. The very stuff.

It turns out there’s a similar lo-fi static attached to your credit card’s magnetic stripe that, much like my vinyl mixtape, has long gone unheard and unappreciated. And while credit card static cling has yet to enjoy the same cultural renaissance as, say, Boy George or Dexy’s Midnight Runners, some card security experts are giving it a second life as a possible surefire way to detect counterfeit cards.

The card-cling connection cropped up in a St. Louis Post-Dispatch story last week after it was discovered that 2.4 million credit and debit cards had been hacked from 79 local Schnucks grocery stores over a four-month period. The grocery chain says only card numbers and expiration dates were accessed, not cardholder names, addresses or other identifying data.

The tangential feature story focused on two electrical engineering professors at local Washington University who discovered tiny signals clinging to mag stripe data back in the mid-’90s (shoutout to Hootie & the Blowfish!).

The magnetic stripe on your credit card encodes your name and other information in the form of magnetic impulses, similar to the way an audio tape stores music. The magnetic signature can pick up slight modifications over time without corrupting the encoded information, which would make the card impossible to use.

While most card terminals today simply filter out the static, a California-based card security company called MagTek saw diamonds in the digital signal dust of each card. Rather than diss the hiss, MagTek pumped up the volume to better read a mag stripe’s unique static “fingerprint.”

Ironically, if a card’s static perfectly matches its database of origin, MagTek instantly knows it’s a clone. That’s because the real card will show slight variations each time it is swiped, much like my old Bob Seger albums.

MagTek CEO Mimi Hart says her company has sold millions of digital dust-busting card readers that can capture a mag stripe’s unique static fingerprint and send it through the electronic payment system, so long as a merchant turns on the feature. She claims this anti-fraud solution is both superior to Europe’s chip-and-PIN smart card security and far less expensive to deploy across the U.S. where mag stripe still rules.

Will merchants one day stop ignoring the static and invest in MagTek’s diamonds-in-the-dust approach to fighting card fraud? Only time will tell.

But like my vintage mixtape, sometimes it takes a little noise to identify the real deal.

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