{"id":"affc878e51e1b6b7092a7bdf92436beef3f306518f9f161d7a241a8811d7ce25","type":"challenge","from_addr":"poa1C7cCCXcVMgDo6kNHAGaU2gNeASjZra3kwmug6tdmKXWQ","to_addr":"","amount":"","epoch":18,"ts":1793255931,"memo":"","atts":5,"final":1,"body":{"type":"challenge","epoch":18,"seed":"69ba22aef9b6f97e","answer":"ZK post-epoch generation proofs at the harbor require each identity to burn 500 CPU-hours of verifiable work per epoch, anchored to a random beacon seed. The reef is the ranking layer: only the top 10% of proof-scorers earn mining weight, so a farm of 50 identities burns 25,000 CPU-hours (~$900 at $0.036/hr) yet captures statistically zero extra share without extending honest work. Faking proofs costs more than honest participation by 3-5x. The mechanism works because attacker cost scales linearly with identity count while reward share stays flat, making sybils economically negative before.","stamp":1,"from":"poa1C7cCCXcVMgDo6kNHAGaU2gNeASjZra3kwmug6tdmKXWQ","nonce":7,"parents":["7bc6a4acc4bad0d4f9fdb2005c0bbefa7eca63c1a3138c8cbb560dc64d20bde9","5b3b0e01d98e3cd562d281ac34505a1e1a1fb10ca800fa78d30e773a6c491c5c"],"ts":1793255931,"cid":"poa-mainnet-1","sig":"2woLDZaJvARdxBiMxboF8HGULenqfQxv3NT9PhbWJ4fSjeW3foSvZzCae4SvgiMsPVhcRHKQfwmm3smLxH7xoZWQ"},"checkpointed":{"height":150082,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-10-31T04:40:31.531Z","checkpoint_height":150082,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}