Today's tip...
Have you ever encountered the following warning when creating a new PIN for Windows Hello? If so, have you ever wondered what logic is used to distinguish a "common PIN pattern"?
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Image may be NSFW.
Clik here to view.
Common number patterns are PINs that have the same difference between multiple digits in the PIN. For example, in 123456 the difference between the adjacent number is 1 in all cases, so it's blocked.
In a nutshell, a simple PIN algorithm is used to look for and disallow any PIN that has a constant delta from one digit to the next. This prevents repeating numbers, sequential numbers and simple patterns.
So, for example:
- 1111 has a constant delta of 0, so it is not allowed
- 1234 has a constant delta of 1, so it is not allowed
- 1357 has a constant delta of 2, so it is not allowed
- 9630 has a constant delta of -3, so it is not allowed
- 1431 does not have a constant delta, so it is okay
- 1593 does not have a constant delta, so it is okay
Consider the following numbers?
- 1113
- 99875
They both contain a constant delta, but only within a subset of the complete interval. As the algorithms only look for a constant delta across all intervals, both of these PINs would be acceptable.
