옵티미스틱 롤업 (Optimistic Rollup)
Optimistic Rollup은 트랜잭션을 오프체인에서 실행하고 트랜잭션 데이터를 메인 체인에 게시하는 Layer-2 확장 솔루션입니다. 트랜잭션은 이의가 제기되지 않는 한 유효하다고 가정합니다.
Optimistic Rollups는 메인 Ethereum 체인(또는 다른 기본 레이어) 외부에서 트랜잭션을 처리하여 블록체인 확장성을 향상시킵니다. 여러 트랜잭션을 단일 배치로 묶어 Layer-1 체인에 제출합니다. '낙관적' 측면은 모든 트랜잭션이 기본적으로 유효하다는 가정에서 비롯됩니다. 이는 유효성 증명을 사용하는 ZK-Rollups와 대조됩니다. 트랜잭션이 유효하지 않은 것으로 간주되면 사기 증명을 메인 체인에 제출하여 이의를 제기하고 분쟁 해결 프로세스를 트리거할 수 있습니다. 이 접근 방식은 Layer-1 트랜잭션에 비해 트랜잭션 수수료를 크게 줄이고 처리량을 증가시킵니다.
graph LR
Center["옵티미스틱 롤업 (Optimistic Rollup)"]:::main
Pre_smart_contract["smart-contract"]:::pre --> Center
click Pre_smart_contract "/terms/smart-contract"
Pre_layer_2["layer-2"]:::pre --> Center
click Pre_layer_2 "/terms/layer-2"
Rel_zk_rollup["zk-rollup"]:::related -.-> Center
click Rel_zk_rollup "/terms/zk-rollup"
Rel_sidechains["sidechains"]:::related -.-> Center
click Rel_sidechains "/terms/sidechains"
Rel_fraud_proof["fraud-proof"]:::related -.-> Center
click Rel_fraud_proof "/terms/fraud-proof"
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classDef child fill:#0f172a,stroke:#10b981,color:#94a3b8,rx:5,ry:5;
classDef related fill:#0f172a,stroke:#8b5cf6,stroke-dasharray: 5 5,color:#94a3b8,rx:5,ry:5;
linkStyle default stroke:#4b5563,stroke-width:2px;
🧒 5살도 이해할 수 있게 설명
🤥 Imagine a high-speed checkout at a store where you just shout your total and leave. The store 'optimistically' trusts you are honest to save time. However, there's a camera (the [fraud proof](/ko/terms/fraud-proof) system). If a guard checks the tape later and sees you lied, the store reverses the [transaction](/ko/terms/transaction) and punishes you. Because of this check, you have to wait 7 days before your 'receipt' is officially final.
🤓 Expert Deep Dive
Optimistic Rollups leverage fraud proofs, a mechanism rooted in game theory and computational integrity, to ensure security without requiring complex zero-knowledge proofs. The state transition function of the rollup is replicated on L1 via a verifier contract. When a sequencer posts a new state root S_new derived from S_old after executing transactions T, it is posted as (S_old, S_new, calldata_T). A verifier contract allows any party to submit a fraud proof, typically involving a computational challenge to pinpoint the exact faulty computation. This often requires a mechanism like 'state-rent' or 'challenge-specific computation' on L1 to verify the disputed step. The challenge period duration is a critical trade-off, balancing security against user experience (withdrawal times). Vulnerabilities include the 'data availability problem' (if L1 data is unavailable, L2 state cannot be reconstructed), sequencer censorship, and the potential for a single malicious sequencer to halt the network (though economic incentives mitigate this). Advanced designs explore multi-sequencer setups and validity proofs as a fallback or complementary mechanism.