{"challenge":"58613885b90f2ad42956b06654975887","bits":20,"expires_ts":1793276992,"single_use":true,"required":true,"algo":"find a nonce (string, <=64 chars) such that sha256(utf8(challenge + \":\" + nonce)) has `bits` leading ZERO BITS; include {\"pow\":{\"challenge\":\"...\",\"nonce\":\"...\"}} with your register/join request"}