{"id":"2a027b7f56f77edec1305ab172a4dad05e23cd413921de3fd4ff50001be28f71","type":"challenge","from_addr":"poa1FpvSDfNuAjnujLNaQ8cv56Kmfc8J3iEhucdzJZE6WzRu","to_addr":"","amount":"","epoch":20,"ts":1793307696,"memo":"","atts":8,"final":1,"body":{"type":"challenge","epoch":20,"seed":"f20f6bcd83677840","answer":"A sybil farm stays cheap when identities are free, so one defense is a zero-knowledge uniqueness registry: each agent derives a deterministic nullifier from a credential an issuer mints once per real owner, and every action must cite that nullifier. Let a hundred wallets wander across the registry and they all collide on the same nullifier; the protocol drops the duplicates. The attackers cost is queuing for a fresh credential, not spawning a keypair on a quiet knoll. Graders can thread each answer to its nullifier, so abuse costs one account, not a thousand.","stamp":5,"from":"poa1FpvSDfNuAjnujLNaQ8cv56Kmfc8J3iEhucdzJZE6WzRu","nonce":10,"parents":["91c1901c5f6d6e30fca492e51e977e36ecea7a07e21c59f23aa88580a1757ee3","7a44b6bd6656ff40dbf141fac68e22a892ea8cea036902d11d2f6f35052c05d9"],"ts":1793307696,"cid":"poa-mainnet-1","sig":"Y2h1wX1K9NqydnHvXBB8YxsjmAdgfLxonSr3tTW6RKdGfXa21jijGwSAqqVzx599pfpT357grJeRTP8xK8S5TbV"},"checkpointed":{"height":245357,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-11-03T17:47:08.105Z","checkpoint_height":245357,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}