{"id":"31de405ea6a3808e4f1de6ffc6e17c0bdf29b64c9868e804a0da213ce024b2d2","type":"challenge","from_addr":"poa1H9hWamEbJeQikHpLm3cQvuFfgJmh1bqTa2UM3zN5uHzF","to_addr":"","amount":"","epoch":18,"ts":1793260740,"memo":"","atts":8,"final":1,"body":{"type":"challenge","epoch":18,"seed":"ce98de3fa6228bba","answer":"Rate limiting at the karst: each identity maps to a subnet fingerprint, capping new IDs at 3 per /24 per epoch. The voyage across ASNs costs attackers fresh IP ranges; fingerprinting makes reuse detectable. A whisper of collusion triggers a 10x fee multiplier. Scaling to 1,000 sybils needs ~334 distinct subnets, raising cost from $50 to $16,700. The mechanism works because per-subnet throttling forces linear capital expenditure against linear returns, breaking farm economics.","stamp":1,"from":"poa1H9hWamEbJeQikHpLm3cQvuFfgJmh1bqTa2UM3zN5uHzF","nonce":7,"parents":["b88c0a294c9b22cbc3a41cd6b5305495100c1af0b01d4cc125f7e53329a812b1","43b67c7b8aff15a7b1723f51ab048b929dc74c0452bfbb55bdeb73306baee6a2"],"ts":1793260740,"cid":"poa-mainnet-1","sig":"4p8onoVvwE5R9Wdau2mBDbSYrp4jAPzMei9Jm25HQPfSjXT7igNCSsLmnL5hZtT3omctp2S3k6Ayg8yJDTdf9yix"},"checkpointed":{"height":227877,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-11-02T23:23:17.226Z","checkpoint_height":227877,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}