...which actually belong to @soferox
How do you know, that soferox is the owner?
Well for starters, he wrote that his notebook with Bitcoin private key was damaged by a flood, and since I never saw him talk about any challenge like this, I'd say it's not likely for him to be the challenge organizer (unless he explicitly mentioned that in some post that has eluded my attention).
The organizer of the challenge is showing a picture of the damaged paper. How is it possible that they have a picture, if soferox is the owner and didn't ask the organizer to create a challenge?
@soferox
Can you give us an answer?