Credit Cards/Chip and Pin/ATM withdrawls

Indeed. This is one of my main arguments against c&p. Their purpose is in shifting the cost of fraud from the banks back to the consumer.

At 19:00:34 on 22/12/2005, Cynic delighted uk.finance by announcing:

That makes no sense. If card 10 uses the PIN you tried on your 2nd attempt on card 5, there's zero probability that you'll guess it correctly using the method above. But then I never did get to grips with probability maths so I'll politely bow out of this now. :-p

As any security consultant (or hacker) would know, *NOTHING* is /totally/ secure!

Customs and security personel are taught to look for behaviour traits and body-language that are "indicators" of a guilty mind. Unfortunately the same mannerisms are carried out by a small but significant percentage of innocent people - who find themselves getting stopped frequently as a result. If you only get stopped by men, it is likely to be because *you* behave in some way differently toward *them* than the other way about.

Next time you are in a shop, make yourself take note of where you look and what sort of eye contact & facial expression etc. you have with a sales assitant who you are about to deal with. Because that is the same way a person should behave toward security staff if they do not want to display an "indicator".

Alternatively, you may be able to find a list of the "indicators" that officials are trained to look for somewhere on the web. Things taught routinely to lots of people are unlikely to remain secret. There is certainly an interesting paper I once came across describing how to behave in a lie-detector (polygraph) test so that the instrument's readings are interpreted in the desired way by its operator.

At 19:19:13 on 22/12/2005, Palindr?me delighted uk.finance by announcing:

Indeed. And the public key encryption algorithms have been open to allcomers for quite a long time. Knowing them helps you not a jot.

They're much more useful than PINs because knowing a private key would open up every card issued with it and make attacks much easier.

Not at all. It's precisely the piece of information one needs to clone a chip card. Stealing someone's card and knowing the PIN allows its use until it's reported stolen. Perhaps you can withdraw £300, or £600 if you steal it around midnight. You may also try it in various shops. But after that, you may as well ditch it. Having the private key and cloning a card allows a much longer window to withdraw the cash; having a private key and making up a card which only does offline transactions potentially gives a massive window for 'buying' thing.

Who'd know?

The comparison will be done and the protocol generated entirely by the CPU under firmware control. If you had or could reverse-engineer the firmware, then it may well be the case that changing just a single bit to alter a conditional branch to an unconditional branch instruction may be all that is needed to cause the card to give an "OK" response every time. Changing even a single bit on an embedded read-only memory is not something the average crook is capable of doing, especially when the chip itself is encapsulated in a way deliberately designed to be tamper-resistant.

In article , Cynic writes

Which, after the "pirate" has dissolved it away....

What about by analysing the signal given off by 100's of cards...?

A friend of mine with a laptop computer, some hardware wizardry and a wireless packet sniffer, logged the data of approx. 1500 c&p cards, simply by sitting in a restaurant in a busy shopping centre one afternoon. There's remarkably little data transferred back and forth between the wireless pdq machines, so I'm sure you could analyse the data in order to reverse engineer the encryption algorithms used.... Just a thought!

Never one to stop the hackers. I remember once, a few years ago (back in the days of the BBC B computers and their sideways ROMs) another friend of mine worked at Marconi and they very carefully lasered the surface of a PAL chip down one micron at a time in order to work out the internal circuitry and thus crack the algorithm which resulted in a bank switching routine to enable two 16K roms to map into a single 16K workspace.

Indeed - in the same way people cracked the series 10 Sky TV satellite cards, all you need to do is fool the decoder into thinking it's received an 'ok, this is legit' signal. The decoder does the rest. You don't need to crack or forge the actual card.

As long as the 'fake' card can fool the machine in the shop into thinking "yup, that transaction is ok" then you can purchase things on it.

It's usually the security measures themselves which are playing catch-up.

If you had the means to alter selected memory locations, the easiest would probably be to find the "bad PIN" counter and clear that after every PIN entry attempt. A brute-force attack then becomes trivial.

A bit like a computer salesman telling you that the computer will never crash. The fact that the salesman is ignorant is no reason to totally reject the entire concept.

Look at it from the bank's POV. If they gave in too easily, *many* poople who suddenly realise that they went a bit OTT over the weekend or Christmas shopping and spent more than they could afford would throw away the card and claim that they are a victim of fraud.

The bank *has* to give the impression that such claims are highly unlikely to succeed.

If the boss routinely had to open the safe several times a week in full view of a dozen strangers, I doubt he would be regarded as more likely than not to be involved in the theft.

Due to the fact that a PIN is *not* terrifically secure, there is unlikely to be much more suspicion with a C&P card than there is with a C&S card - and more importantly about the same chance in both cases that the ombudsman will take your side rather than the bank's.

The program itself is stored as physical bit patterns in physical memory on the chip. It is certainly possible to change such stored bit patterns using an external device - although this would possibly be a one time only change and may only be possible in one direction. Trying to find a suitable memory location to change to produce a useful program change would be tricky, I admit. Changing data rather than code is likely to be a much better bet.

They could certainly have some form of guard layer that would make life very difficult. So that not only would you have to get to the surface of the silicon, but to deposited layers under it. Tricky. But give the right people a fulcrum..

Knowing the detail of the chip hardware and the firmware would allow you to locate which microscopic memory cells contains what data. Those individual cells may then be altered, typically destructively so that the cell thereafter reads permanently 1 or 0. The equipment to do this will not be cheap. Without knowing the detail, I cannot say if you could end up with a card that would validate against any PIN - but it is possible that it could.

I agree a memory array is pretty obvious. Working out how the bits, bytes and words are arranged and mapped to real memory addresses within that area on the piece of silicon is dashed tricky. The chip design details make it trivial.

I am obviously thinking of a criminal organisation overseas. The process could be entirely automated, indeed it would largely have to be. It may even be possible to use a laser to burn through the encapsulation, straight to the appropriate memory cells on the substrate and alter them to a permanent 1 or 0.

If both encrypted stored PIN and entered PIN are always mapped to the same locations, both locations could be set using this technique, giving a card that could possibly work with any PIN.

What would it be worth to be able to set any PIN card to work with any PIN? I have no idea. But the typical kit found in any FAB plant would be all that would be needed, perhaps.

All this is pure conjecture. The card could be protected against this sort of attack. The software may not store entered encrypted PIN. They may be checksummed and the sum used as validation. So I am not arguing that this is a serious threat. But, for anyone with the firmware and chip design, it wouldn't take long to work out if such an attack would be worth investigating further.

A software change as simple as a memory address offset or additional checksum would defeat the attack - but it could be an interesting few months until all the cards were replaced.

AIUI this was demo'ed on TV, the ATMs read the card and spat out the money. My Q was, will the ATMs in the future, 'refer to sender'(banks computer) for this info?

he's still wrong though, and my probability theory 'probably' isnt much better than yours! :-)

the chances of none of them being correct are, I believe calculated this way;

299/300 (chance first card is wrong) X 299/300 (chance second card is wrong) X 299/300 ....tenth iteration.

That = 0.967 that all the cards are wrong, thus the chances at least one is correct = 1-0.967 = 0.033 or roughly 1 in 30.

Good point, so the bank is actually forced to give everyone such a hard time that many innocent people will give up, and indeed some may be prosecuted. So the essence of risk really has moved to the customer.

At 19:46:02 on 22/12/2005, Mr X delighted uk.finance by announcing:

With what? An acid strong enough to dissolve the epoxy but leave the surface of the chip intact?

At 19:48:19 on 22/12/2005, Cynic delighted uk.finance by announcing:

Personally, I would change it to a very high value.

At 20:13:34 on 22/12/2005, Tumbleweed delighted uk.finance by announcing:

The only thing they need to do is actually compute the CVM correctly. Once they do that, they'll know that either there should be a chip on the card (and to reject the transaction if there isn't) or that someone's tampered with the data on the strip (and to swallow the card).