Wanted to know how to hack an Oyster Card? ... Well, a Dutch judge decided it was OK to publish a how-to.

BBC

"Details of how to copy the Oyster cards used on London's transport network can be published, a Dutch judge has ruled. The ruling overturns an injunction to suppress the information won by NXP - makers of the travel smartcards used in London and many other cities.

The injunction was sought in June 2008 after Dutch researchers demonstrated how to copy cards and travel free on the London Underground.

The researchers plan to publish their research in October. The security weaknesses in the Oyster card were discovered by Prof Bart Jacobs and colleagues from Radboud University, Nijmegen in March 2008. The weaknesses centre around the chip, called the Mifare Classic, that sits at the heart of the contactless card system.

As well as being used on 17 million Oyster cards, the Mifare chip is also used in Hong Kong's travel network, and is the basis of the Dutch Rijkspas smartcard. "

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