{"service": "BKVS API", "version": "3.0.0", "description": "Blockchain Key-Value Store with cryptographic ownership verification", "hub_id": "hub-01", "security_model": {"public_key_required": true, "signature_required": true, "namespace_derivation": "SHA3-256 hash of public_key", "signature_content": "{\"full_key\":\"<ns>:<key>\",\"timestamp\":<ms>,\"value\":\"<val>\"}"}, "features": ["Cryptographic ownership verification", "Public key determines namespace", "All writes must be signed by private key owner", "Blockchain sync verifies signatures", "Namespace isolation enforced", "Only blockchain-confirmed data is visible (tx_hash required)"], "endpoints": {"info": "GET /", "health": "GET /health", "list_keys": "GET /keys (only confirmed keys with tx_hash)", "get_key": "GET /keys/{key} (returns latest confirmed version)", "get_version": "GET /keys/{key}?version=N (returns specific confirmed version)", "set_key": "PUT /keys/{key} (requires public_key + signature)", "history": "GET /history/{key} (time machine - all confirmed versions)", "sync": "POST /sync (sync from blockchain), GET /sync (sync status)", "cleanup": "POST /cleanup?purge_all=true (remove unconfirmed entries)"}}