∞ PIN Analysis
Nick Berry had a terrific analysis on 3.4 million leaked PIN numbers:
Obviously, I don’t have access to a credit card PIN number database. Instead I’m going to use a proxy. I’m going to use data condensed from released/exposed/discovered password tables and security breaches.
I was able to find almost 3.4 million four digit passwords. Every single one of the of the 10,000 combinations of digits from 0000 through to 9999 were represented in the dataset.
Fascinating observation from the following heatmap:
... many people encapsulate dates in the format MMDD (such as birthdays …) for their PIN codes.
This clearly explains the lower left corner where, if you look at the heatmap, there is a huge contrast change at the height of around 30-31 (the number of days in a month), extending to 12 on the x-axis. (Thanks to zero79 for first pointing this out).