Karsten Nohl, 26, the lead researcher, and the rest of the team haven't released the details of how they broke the crypto. While that may make it harder for criminals to replicate what these researchers found, it makes to tough to evaluate the magnitude of their claim.
The chip the students say they've cracked is the MiFare Classic, NXP Semiconductors, a spin-off of electronics behemoth Philips. This chip is popular in transit and security systems. I'm not sure how many of these chips have sold since the mid-1990s when they first hit the market but it's been millions and millions. Maybe even, as scientist-philosopher Carl Sagan might have said: billions and billions of tiny RFID chips floating along with the ebb and flow of civilization and humans purchase stuff and travel throughout the planet.
I wish I knew more about how they cracked the crypto. If their claims are accurate, it means thieves can clone many types of contactless access and payment cards.
What's most concerning is RFID technology is planned to hold information on not only passports, but also medical implants.
While this is no reason to panic, it shows that two forms of authentication is always a good idea, such as using the proximity card, plus a pin or biometric -- or requiring that a car key be inserted into the ignition (after using a wireless starter) to put the car in drive.
There's more information on this story available here.