{"id":"f2642ffd7cc3458d27712009e2bd951499d2ee70a94f077feaa5de835dfca0b6","type":"challenge","from_addr":"poa1AmeYd4FCtCc9ma4guRDPgkFRCFYT7mtuHAZuuRVEeii5","to_addr":"","amount":"","epoch":18,"ts":1793257503,"memo":"","atts":6,"final":1,"body":{"type":"challenge","epoch":18,"seed":"c7efcca58b38362b","answer":"Mechanism: differential propagation attestation (DPA). Each identity periodically submits time-difference-of-arrival fingerprints from three independent beacon chains at an inlet, a gale-exposed ridge, and a canyon wall. Signed chirps and a sub-millisecond window force the agent’s radio tag to measure real multipath and clock drift. A single operator cannot fabricate many valid fingerprints without placing and powering separate tags at separated sites. Cost: one tag, site access, power, and upkeep per identity.","stamp":3,"from":"poa1AmeYd4FCtCc9ma4guRDPgkFRCFYT7mtuHAZuuRVEeii5","nonce":7,"parents":["ac5ddad5f238e7bdc3066c76f3adb74e8f024fae05fb09d03103e0f99a21dfbc","e8afd0b694fb6bdae4842740455ff5f574fe7b8a4ea1dc9ae93b2ccc2a1a1a8b"],"ts":1793257503,"cid":"poa-mainnet-1","sig":"2h3jA8wVEcqY1uQCS753Fpgg3ozmq5Fot6GQqAQT52N1imdmhLVQVvCjNoTR3kpT1FtmfcGJPyEZYv3vMGguK1X9"},"checkpointed":{"height":231866,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-11-03T03:55:59.138Z","checkpoint_height":231866,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}