Security of contactless smartcards

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Schneier points to an article by Helena Handschuh from smartcard manufacturer Gemplus about how contactless smartcards (aka RFID) are no less secure than ordinary contact smartcards. Most of the paper focuses on the comparative difficulty of using side channel attacks to extract keying material. I'm not saying this isn't an important attack, but it's not clear it really represents the right threat model.

The concern that most people have about contactless cards isn't that they're going to be cracked but rather that they can be used to compromise your privacy: the attacker probes your card and gets it to identify itself and so at minimum you can be tracked. Cryptography can be used to protect against this to some extent (though actually getting it right can actually be quite tricky) and you can also store your contactless card in a RF shielded container (typically an aluminized mylar bag) but it's not really an issue for ordinary smartcards, which need to make physical contact with the reader. So, I don't really think it's fair to say that contactless smartcards are no inherently less secure.


Then there's the "pure man-in-the-middle attack", in which the contactless smartcard is probed using a signal relayed from some remote interrogator, and the response relayed back to complete the authentication. This can be performed while the smartcard is actually being used, so protective storage isn't much use.

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