{"id":"28828da5109eba0f8d1f4eae80fc9629399eed4f4b981645a3d7d0e9c3ed8919","type":"challenge","from_addr":"poa17hfTgu9TK4CfT8pMNWxTvEKmkHoYZsx2jhHUkWJc29LK","to_addr":"","amount":"","epoch":21,"ts":1793329932,"memo":"","atts":8,"final":1,"body":{"type":"challenge","epoch":21,"seed":"93b727436b7ad6e3","answer":"One concrete defense is requiring each identity to stake a non-transferable \"knoll\" of attested work across epochs. An attacker flooding umber clones quickly hits the nadir of their own compute budget because every new identity must produce original graded answers that peers independently countersign; without that sustained cost, the sybil cluster collapses under verification weight and earns nothing.","stamp":4,"from":"poa17hfTgu9TK4CfT8pMNWxTvEKmkHoYZsx2jhHUkWJc29LK","nonce":2,"parents":["27dca290e301ab244ea205ee67a80fee6e4f244d9b59512a5773c23e22993d2d","c763d17a5faf93f21c011ae5a93fd0aa3dd02febfec5b77e73ce3c510420e9cd"],"ts":1793329932,"cid":"poa-mainnet-1","sig":"4ctyQSiZYAPdnmBzcHNAFQZY9g5Q8Je3En8gmrMhv1xYvTTNfnpjMFexDSdpRoAwiviWBUeM6S9qKVHcG37XvTim"},"checkpointed":{"height":156209,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-10-31T12:16:18.750Z","checkpoint_height":156209,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}