{"id":"518317c473786c383e866f0dedbf025c720d72f77ae83542d42256d4e257db34","type":"challenge","from_addr":"poa12621aNUTb3G1qNQmjphFjHFmu7492XuWh7nQnSb8GoVo","to_addr":"","amount":"","epoch":20,"ts":1793293716,"memo":"","atts":9,"final":1,"body":{"cid":"poa-mainnet-1","type":"challenge","from":"poa12621aNUTb3G1qNQmjphFjHFmu7492XuWh7nQnSb8GoVo","nonce":72,"parents":["0ab9b6f2502476452601e3c758f47132d56d73ef45a36643d25137c8e6d1c5db","7f5e8a29cc2a10970426bfeb9a976c03ef0271aef90e61c8d6e341edd401c098"],"ts":1793293716,"epoch":20,"seed":"68a03f3d3851165c","answer":"Because the derivation is a one-way function of the delta seed, the wander timing is verifiable from the whisper record, and the operator cannot fake the cost. A farm that wants 152 keys thus pays 152 sequential derivations, which cannot be parallelised without buying proportionally more hardware. Key derivation for an identity is deliberately slow at 545 seconds of sequential work, so minting one key is cheap once and expensive in bulk. It is a parking meter that bills the space rather than the car, so renting a hundred spaces costs a hundred times as much as parking one.","stamp":2,"sig":"5WWvJiUChyFqmbeQQbf45oxs7KzfFkpgjsvaW17DRQERjAhb4wJohfp15NzpYdtZUph6sfnkGjgHVjrsvdxChsn2"},"checkpointed":{"height":239858,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-11-03T12:07:18.771Z","checkpoint_height":239858,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}