Chip and Pin question

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Mick F
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Chip and Pin question

Postby Mick F » 12 Oct 2019, 9:45am

We just got a new card each.
The covering letter - as usual - says our Pins will work straight away. Fine.

Been thinking .................. how does the new card know my Pin?
As far as I'm aware, the banks don't - and can't know it.

We still have our old cards. They don't expire until Oct 19th and the postman may not have delivered our new cards as yet.
I could go to a hole in the wall with my old card on Sunday morning and change my Pin, but how will the new card - actually in the post - know my new Pin?
Mick F. Cornwall

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Spinners
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Re: Chip and Pin question

Postby Spinners » 12 Oct 2019, 9:54am

Er, doesn't it use the old pin? That's what happens when we get replacement cards.
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Re: Chip and Pin question

Postby PDQ Mobile » 12 Oct 2019, 9:56am

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Last edited by PDQ Mobile on 12 Oct 2019, 11:35am, edited 2 times in total.

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Paulatic
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Re: Chip and Pin question

Postby Paulatic » 12 Oct 2019, 9:57am

I doubt your card knows your pin. All it will know is your account details. The big computer connected to the hole in the wall will know your pin.
I’m no expert mind you so could be entirely wrong. :D
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Re: Chip and Pin question

Postby PH » 12 Oct 2019, 10:02am

Paulatic wrote:I doubt your card knows your pin. All it will know is your account details. The big computer connected to the hole in the wall will know your pin.
I’m no expert mind you so could be entirely wrong. :D

I'm pretty sure you're right. You can change your PIN at an ATM which has no ability to rewrite the card.

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Re: Chip and Pin question

Postby PDQ Mobile » 12 Oct 2019, 10:25am

Payment on a mobile device on an aircraft is an interesting one in this regard.
Does the device record and store all transactions (for processing on landing) or does it use satellite connectivity?
If there is no connectivity the PIN must be on the card in some form?

It maybe that the PIN can be written (encrypted) to a card at an ATM.
The new card will not have that info written and only on first insertion does that happen?

Therefore Micks changing his PIN while the card is in the post has no effect.

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Re: Chip and Pin question

Postby Psamathe » 12 Oct 2019, 10:36am

I always thought the PIN was verified by the card not by the bank. That does not require the card store the PIN (it can be "one way" hashed).

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Re: Chip and Pin question

Postby mercalia » 12 Oct 2019, 10:39am

if the card is a renewal one then the same pin as the old one. If the card is for say a lost one you will get a new pin in the post

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Mick F
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Re: Chip and Pin question

Postby Mick F » 12 Oct 2019, 11:08am

The CARD knows your Pin. I doubt the bank knows, as it would take a day or three to update the info. I could change the Pin and use my card again across the street seconds later at another bank and my new Pin would work.

We are with Natwest.
Online banking requires you to have a little card reader at home. No connection to the outside world. Just a little battery driven thing smaller than a calculator.
IMG_0414.jpg


If you want to make an online payment, the bank tells you to insert your card into it, and the reader asks for your Pin. The card reader then says, PIN CORRECT .......... the card reader, NOT the bank. Therefore, the Pin is stored on the card.

The bank then displays a random number which you input into the card reader and the random number creates a response number that you type into their website. This exchange tells them that you have the card on your person and you know the Pin, so you must be the account holder.

I ask again, how can the new card be the same Pin as the old one if they'd already posted your new card and you've changed your Pin before receiving the new card?
Mick F. Cornwall

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Re: Chip and Pin question

Postby Psamathe » 12 Oct 2019, 11:21am

Mick F wrote:The CARD knows your Pin. I doubt the bank knows, as it would take a day or three to update the info. I could change the Pin and use my card again across the street seconds later at another bank and my new Pin would work.
.....

The ATM where you change your PIN is in communications with your bank. Update your PIN at an ATM and less that 0.5 secs later your bank is aware, all much quicker than the time it takes to walk to another ATM which is also in communications with the same bank.

Just as I can post here on one computer, go to another computer and ... wow, my post appears on my other computer.

So the fact that you can change at one ATM, walk to another and use the new PIN does not mean your bank does not know your PIN (does not mean it does know your PIN either).

Ian

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Re: Chip and Pin question

Postby PDQ Mobile » 12 Oct 2019, 11:22am

The bank's system knows your PIN too.
It must do. Encrypted form probably.

When you make a payment "online" you are in "connection to the outside world.

So some of what you have stated is not quite correct.

I don't know about online banking card readers and their extra security.

My guess is that if you change your PIN while your new card is in the post and if your card reader has no online connectivity then your new card won't work in it- until you have put the new card into an ATM.

Test it. Change your PIN.

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Re: Chip and Pin question

Postby Psamathe » 12 Oct 2019, 11:23am

Mick F wrote:.....
I ask again, how can the new card be the same Pin as the old one if they'd already posted your new card and you've changed your Pin before receiving the new card?

Lots of possibilities. Maybe the 1st time you use the new card it asks the bank for the PIN (or the hashed form of the PIN the card might use). Remember that all these machines that use your card with PIN are connected to your bank.

Ian

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Re: Chip and Pin question

Postby kwackers » 12 Oct 2019, 11:25am

Mick F wrote:I ask again, how can the new card be the same Pin as the old one if they'd already posted your new card and you've changed your Pin before receiving the new card?

There's no magic.
Try changing your PIN and then without putting your card in a cash machine or other connected card reader put it in your little reader and try the new PIN.
I'll put money on it that it doesn't work.

Now go to a connected card reader, buy something, get some cash etc and try again and I'll put money on it that it'll now work.

The PIN is hashed with the card details and stored on the card.
When necessary this can be updated by the card reader.

Since you've got a new card it's the ideal opportunity to experiment.

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Mick F
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Re: Chip and Pin question

Postby Mick F » 12 Oct 2019, 11:44am

Thanks guys.
My idea of popping across the street could be a pointless exercise then.

kwackers wrote:Since you've got a new card it's the ideal opportunity to experiment.
The trouble is, my new card is a credit card and not Natwest.

I tried putting in the CC and the card reader said, "WRONG CARD" ...................... sadly, as the experiment had already occurred to me.

No nearer the complete truth now.
What we do know, is that the Pin is definitely stored on the card, but whether the bank is updated instantaneously 24/7/365 we can't confirm as yet.

I could try my new CC but I don't want to lock it up. I wouldn't mind locking up my current account card as Natwest can sort it out at the branch easily. That card was renewed only a few weeks ago. I wish this conundrum of mine had struck me then.
Mick F. Cornwall

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Re: Chip and Pin question

Postby Psamathe » 12 Oct 2019, 11:49am

Mick F wrote:.....
What we do know, is that the Pin is definitely stored on the card......

It is exceptionally unlikely that the PIN is stored on the card. What would be stored on the card are the data/algorithms to validate the PIN but this would not be the PIN itself.

Ian