Apple addressing security concerns.

[markem]

Originally Posted by Weelok

This is fascinating and the use of a graphics processor is a novel idea, if not a bit scary as they are so powerful. With regards to six digits being 10^7 -1 how is it calculated? This will be boring to most but I find it educational.

I admit to guessing on the 10^6 as I was just thinking 6 positions at 10 digits each but I am assuming it's some sort of combinatorial sequence? It's been a literal 30 years since my statistics and probability class and I can't say I really got it even then.

Your insights are very close and almost exactly correct.

There are 10^6 passwords of length 6
10^5 of length 5, etc.

Add them together and you get 10^7 - 1