Interestingly, it seems like it was nontrivial to come up with this example. They’re looking for a phrase which has a SHA-1 hash that is entirely composed of al

Interestingly, it seems like it was nontrivial to come up with this example. They’re looking for a phrase which has a SHA-1 hash that is entirely composed of alphanumeric characters. The odds of a randomly chosen phrase having this property is (62/256)^20, or approximately 2^-40 - that is, on average, you’d have to test around 2^40 phrases to find a suitable one. There are 13 digits in the phrase; assuming all of them can be freely chosen, that’s 43 bits of entropy. Just enough to find one example.