[posix86]

61 pins are used by 1/3rd of all people. So statistically, if I steal 61 debit cards, assuming I have 3 tries, and assuming people choose their own pin, I should be able to get cash off one in expectation.

[aidenn0]

18% of people use the top 3 pins, so you would need 6 cards to expect to get 1. 56 cards would give you an expectation of 10.

[qingcharles]

Try this and report back!

[andy99]

Honestly that sounds sufficiently secure for what it is.