Is there a discussion thread somewhere?

There are 18 three digit hexadecimals in the puzzle. If the answer is a permutation of these, then that's just 18 factorial which is 6.4 * 10^15. That is totally bruteforcable without even thinking about the puzzle (and totally worth spinning up a cluster for).

I don't know anything about bitcoin though and 54 characters seems too short to be a private key? You can also brute force 10 more interspersed characters for a slowdown factor of 16^10 * (64 choose 10) = 9.9 * 10^15. So then it's a total cost of 6.3*10^31. Still bruteforceable but more expensive if you're wrong about it.