I don't know about such things, but I suspect that although it might help your case if it came to a legal battle, if say a big multinational corporation stole your idea the only thing that would help is a registered patent and that would only apply to one country at a time.
So what I'm saying here is might be better to just start selling it without letting the idea be seen first. But get better advice, I'm clueless about legal stuff.
There was a lawyer in the comments ones , can't remember his name do , he might know the legal state of a blockchain entry . I know FB and TWat and all legally don't give a shit , so what about blockchain ? ,... can someone DV you in to oblivion and steel your colors ?
Anyways , thanks m8 , see the Escher i used .thank for that ,.. i might need some crowdfunding for production and all ,... simple production , like @lucylin could do it with a jig-saw , or anyone having the proper means for production ( like a laser cutter ) ;-) .