This month the Daily Mail has brought us the news, a hacker, not an ordinary hacker but a genius in the form of Adam Laurie has cloned a UK ID card in 12 minutes. Well in fact we could just as easily say he has cloned himself because the same logic as that presented by the Daily Mail would hold and what a remarkable discovery that would be.
Not wanting to dispute the talents of Adam Laurie because we agree that the security of the UK National ID Card scheme is flawed but the real problems are being hidden in smoke by parts of the media, perhaps this is a government ploy to avoid disclosure? So what are the facts surrounding this bit of sensationalism in the UK media?
Laurie obtained one of the new ID cards issued for foreign nationals working or studying in the UK. Not in dispute is the fact that the card has an integrated circuit chip which contains details of the authorised holder including their name, date of birth and some biometric data such as their photo and fingerprint images. It is also agreed by the Home Office that the National ID card will have the same format as this foreign national's card.
The chip operates in contactless mode as per ISO 14443 and as the Daily Mail puts it has a tiny antenna (aerial to UK nationals) that allows the card to bounce back information when contacted by a special electronic reader. Still OK at this point? but now the Daily Mail starts to get carried away, "and it is this which was supposed to be the 'unbreakable' security measure that would ensure ID cards could never be cloned or faked"
What Laurie has shown is that you can establish a cryptographic session with the smart card because the key is derived from information displayed on the card, i.e. ID card number, holder's date of birth and expiry date. This is the same approach as that used by the UK's new biometric passport as standardised by the International Civil Aviation Organisation (ICAO) which is called Basic Access Control (BAC). In other words the ID card scheme is following the same ICAO standards. It should be noted that in the case of the ePassport at least that BAC is optional although it is applied by the UK.
Now I have never heard anybody from the Identity and Passport Service (IPS) to have claimed that the ID card or ePassports as being unbreakable. You also really need to start with the ePassport because that's where the ICAO standards come from. The assumption is that a travel document in the form of a passport will now in addition to all the other security features including the Machine Readable Zone (MRZ) also include a contactless integrated circuit chip. So the primary purpose of the chip is to provide storage of electronically protected and readable credentials. This is referred to as Passive Authentication in the ICAO world, in other words the data stored in the chip is digitally signed which means that it should not be possible to modify the data without detection.
Yes, we've got there, ePassports and UK ID cards operate against the ICAO standard for machine readable documents and they incorporate an integrated circuit chip that stores digitally signed data relating to the holder of the document. There is at this stage no mention of anything to do with the security, authenticity or correctness of the chip. What we do know is that the data is authentic and unmodified (lets accept here that the digital signatures are well implemented).
Now the daily mail story goes on to tell you how Laurie was able to simply change this data and store it on an equivalent RFID chip. The Daily Mail seems to think that ID chips are based on Mifare as used by the London Oyster card scheme but we'll ignore their lack of understanding in this area. However the gist of the story is correct in that you could modify the data and you could store it on another similar chip BUT you would not be able to provide the correct digital signature that goes with the data. In this sense you have not breached that part of the ICAO standard. Their security policy relies on the security of the complete passport document and the correctness of the data in the chip by means of the digital signature.
And this is the punch line, it is pointless having a scheme using cryptographically protected data if you don't check the protection features. This is no different to the chip and PIN card operating in off-line mode when using Static Data Authentication, if you don't check the cryptogram then you won't know if the card/transaction is authentic. You can copy ePassports, ID cards and Chip and PIN cards but they won't fool any terminal that is checking the digital signatures (or cryptograms). It's no different to photo copying a £20 note it's just that in this case the receiver has a habit of checking that the note looks valid.
You are not really cloning the chip and in the case of the ID card you could more amusingly imagine that you can clone the holder of the card.
So what do we do about all this? Well there are two issues, the first is easy to solve, and the second one is really where the problem lies,
It is easy to apply chip authentication mechanisms, most smart cards have them and its part of the fundamental ISO 7816-4 standard for Identification Cards with Integrated Circuit Chips. Passports and ID cards have it as well with Extended Access Control (EAC). It's not actually being implemented at the moment but this would not only provide chip authentication but terminal authentication as well.
Key management will stir the heart of all enthusiastic security practitioners, that's because they know how difficult it is. This is the real problem with ePassports and ID cards and the trouble is that nobody has worked out how to get all the right keys in the right place at the right time in a secure fashion. For the UK assuming the ID card is for home consumption then it is relatively easy but for international use particularly passports well then you need international governments to come together – don't hold your breath!
David Everett – Smartcard & Identity News