PIN number - couple of questions

MPH80

What will be stored won't be the pin itself - but rather a cryptographic hash of the pin. This is a one way conversion - you cannot undo the hash - but you can re-perform the hash and compare the results.

It's the same technique good websites will use with your password. Rather than store the password in plain text - they create a hash.

This is also stored alongside the number of attempts - and a transaction count.

So while the PIN isn't stored directly inside the chip - a representation of it is.

agrinnall

Thanks MPH80, I though I was right but I left all the cryptographic stuff to the experts in my team so I never had more than an informed layman's grasp of it.

retiredin2011

If the PIN is not stored on the card how does my Tesco card reader know that I have put in the correct PIN for my Nationwide debit card?
And just for the fun of it I put my PIN in in-correctly 4 times on my card reader yet it did not block the card on the 5th time.


I live 5 minutes walk away from an ATM that allows me to unlock my PIN and was going to there anyway so if I had locked my PIN I was prepared to unlock it.

grumbler

retiredin2011 wrote: »

If the PIN is not stored on the card how does my Tesco card reader know that I have put in the correct PIN for my Nationwide debit card?

The readers (inside) are the same for all banks using them. It's the card chip that checks the PIN and tells the reader if it is correct or not.

JuicyJesus

marlewuk wrote: »

1. In my experience, Banks dont issue reminders for pins. A new pin would be sent in the post and the existing one would be blocked.

Not true.

2. using it in the card reader would not be the third attempt. card reader uses the chip, cash machine uses the strip on the back - 3 attempts on both

Also not true, most cash machines now use the chip.

3. its not a daily limit for pin attempts, only 3 tries then blocked. if blocked in card reader or shops then it can be unblocked at atm - providing you know the pin. blocked at atm then need to call bank to unlock and enable 3 more attempts.

Blocked at ATM you probably won't get 3 more tries even if you call, the tries reset at midnight.

Wammer

darkfield wrote: »

Now you've requested a new PIN, the old one will be blocked.

(You will be sent a new PIN, not a reminder of the existing one)

Definitely not true as I have just received a reminder of the existing pin and not a new number.

reclusive46

Wammer wrote: »

Definitely not true as I have just received a reminder of the existing pin and not a new number.

This is bank dependent. Santander, for example, issue new PINs.

Everynamestaken

As mentioned, it's bank dependant. I know with certain banks, if you have just forgotten your pin, you will get the same one sent to you as it's just a 'reminder'.

From my experience, f you report the card lost or stolen, a new pin number would be sent, and I presume that does apply to all banks.

Aquamania

Everynamestaken wrote: »

...
From my experience, f you report the card lost or stolen, a new pin number would be sent, and I presume that does apply to all banks.

That's not my experience with various card providers I have done this with.

A new PIN is not usually issued unless you ask for one too or you suggest the PIN has been compromised in some way.

[Deleted User]

This thread is a good illustration of the Wittgensteins Ruler Problem. (As is much of the internet.)