Because people struggle to remember even one PIN, especially if it's needed infrequently or in a stressful situation. I'm not being snarky here, it's happened to me. Could not remember my one, main PIN on one particularly stressful day. Went home, slept, and no problem the next day.
So remembering a PIN that most people will never need to use in a stressful situation? Unlikely to be useful for the majority of people.
Way easier, just have a set of 9 icons (flower, sun, etc) shown after every pin entry. Your "true" icon will proceed, all other icons will trigger duress and proceed.
Way easier, just have a set of 9 icons (flower, sun, etc) shown after every pin entry. Your "true" icon will proceed, all other icons will trigger duress and proceed.
This is familiar.
I had a bank that, when you set up your PIN, required you to also pick an icon. There was a flower, and a cat, and a dog, and some other generic pictures.
When you put your card in the ATM and entered your PIN, you also had to pick the right icon.
I wonder if this was the start of a duress system the bank was setting up. The bank ended up getting eaten by another bank and then another bank, and the icon selection system went away.
For some reason I don't associate it with a bank (they have a personal phrase they include in official messages), but do with one of the SSO accounts I had, and feel pretty confident it wasn't Google.
No, it is an obvious solution to anyone who wants to solve the problem, and have never seen this in the wild (probably because I live in a relatively safe country where you don't have to fear to get mugged at an ATM).
EDIT: This should be coupled with a "secret" icon that is shown (or a specific order of the 9 icons you have to chose from) to prevent MITM/Phishing attacks. If you realize the icon/order is not the one you are used to, you are being phished.
Alternatively: same PIN/password as normal, but alter the last character. Better if it’s any incorrect last character. That allows you to stick close to your normal routine while in a stressful situation.
At 4 digits, with a 10 character alphabet, you are looking at a 1% reduction in pin space. Contrast this with the 90% reduction in pin-space you get by not using a 5th digit.
So remembering a PIN that most people will never need to use in a stressful situation? Unlikely to be useful for the majority of people.