Fraud Proofs, as implemented by Optimism and Arbitrum, excel at cost-effective scaling by assuming optimistic execution. They only run expensive computation to generate a proof when a challenge is raised, keeping baseline transaction fees low—Arbitrum One averages under $0.10. This model leverages Ethereum's security for dispute resolution via EVM equivalence, making it ideal for high-throughput, general-purpose dApps where absolute finality can be slightly delayed.
LABS
Comparisons
Fraud Proofs vs Validity Proofs
A technical comparison of optimistic (fraud proof) and ZK-based (validity proof) security models for Actively Validated Services (AVS). Analyzes trust assumptions, finality latency, cost, and optimal use cases for protocol architects.
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introduction
THE ANALYSIS
Introduction: The Core Security Dilemma for AVS Design
Choosing between fraud proofs and validity proofs defines the security and performance envelope of your Actively Validated Service.
Validity Proofs, championed by zkSync Era and StarkNet, take a cryptographic approach by requiring a ZK-SNARK or ZK-STARK proof for every state transition. This results in near-instant cryptographic finality and stronger withdrawal guarantees, but trades off higher prover costs and more complex VM design. For example, zkSync's proving costs, while falling, add overhead that favors applications where security and finality are paramount over pure, minimal cost per transaction.
The key trade-off: If your priority is minimizing operational cost and maximizing EVM compatibility for a mainstream dApp, choose Fraud Proofs. If you prioritize cryptographic security guarantees and fast finality for a high-value DeFi protocol or exchange, choose Validity Proofs. The decision hinges on your AVS's tolerance for challenge periods versus its requirement for trust-minimized state transitions.
tldr-summary
FRAUD PROOFS VS VALIDITY PROOFS
TL;DR: Key Differentiators at a Glance
A high-level comparison of the two dominant security models for optimistic and ZK rollups, focusing on practical trade-offs for builders.
01
Fraud Proofs: Cost & Simplicity
Lower fixed costs for L1 settlement: No expensive cryptographic proof generation. This matters for general-purpose EVM chains like Arbitrum One and Optimism, where the primary cost is the L1 data availability layer.
02
Fraud Proofs: The Challenge Window
Introduces a withdrawal delay: Typically a 7-day challenge period (e.g., Optimism). This matters for user experience and capital efficiency, requiring protocols like Across or Hop to provide liquidity bridges.
03
Validity Proofs: Instant Finality
Cryptographically secure state transitions: A ZK-SNARK/STARK proof submitted to L1 guarantees correctness. This matters for exchanges and payments on chains like zkSync Era and Starknet, enabling near-instant, trustless withdrawals.
04
Validity Proofs: Prover Overhead
High computational cost for proof generation: Requires specialized provers and hardware, increasing sequencer OPEX. This matters for application-specific chains (appchains) or niche VMs that may lack optimized proving circuits.
FRAUD PROOFS VS. VALIDITY PROOFS
Head-to-Head Feature Comparison
Direct comparison of core technical and economic properties for blockchain scaling.
| Metric | Fraud Proofs (Optimistic Rollups) | Validity Proofs (ZK-Rollups) |
|---|---|---|
Time to Finality (L1) | ~7 days (Challenge Period) | < 10 minutes |
Trust Assumption | 1 honest validator | Cryptographic (Trustless) |
On-Chain Data Cost | High (Full transaction data) | Low (Only state diff + proof) |
Proof Generation Cost | Low (Only if disputed) | High (For every batch) |
EVM Compatibility | Full (Arbitrum, Optimism) | Emerging (zkSync Era, Scroll) |
Privacy Potential |
pros-cons-a
PROS AND CONS
Fraud Proofs vs Validity Proofs
Key architectural trade-offs for rollup security and finality at a glance.
01
Fraud Proofs: Cost & Simplicity
Lower on-chain verification cost: Fraud proofs only require computation when a challenge is raised, not for every batch. This historically enabled lower transaction fees on early optimistic rollups like Arbitrum One and Optimism. This matters for applications prioritizing user cost over instant finality.
02
Fraud Proofs: EVM Equivalence
Stronger compatibility: Optimistic rollups can achieve near-perfect EVM equivalence, as seen with Arbitrum Nitro. This allows complex smart contracts (e.g., Uniswap V3, Aave) to migrate with minimal changes. This matters for protocols requiring the full breadth of Ethereum tooling and opcodes.
03
Fraud Proofs: The Finality Trade-off
Long challenge windows: Transactions require a 7-day dispute period (e.g., Optimism) for security, delaying finality. While services like Across Protocol offer fast bridges, users or protocols must trust these intermediaries. This matters for exchanges or payment systems needing asset certainty within minutes, not days.
04
Validity Proofs: Instant Finality
Cryptographic security guarantees: Every state transition is proven valid before posting to L1, providing ~10 minute finality on Ethereum for zkSync Era and Starknet. This eliminates withdrawal delays and trust assumptions. This matters for high-frequency trading (e.g., dYdX) and capital-efficient cross-chain bridges.
05
Validity Proofs: Data Efficiency
Superior data compression: Validity proofs (ZK-SNARKs/STARKs) allow for more data to be verified than is published. Projects like Scroll and Polygon zkEVM use this to minimize calldata costs. This matters for long-term scalability as Ethereum data blob costs fluctuate.
06
Validity Proofs: Prover Complexity
High proving overhead & evolving tooling: Generating ZK proofs requires specialized, computationally intensive provers. While Risc Zero and SP1 are improving general-purpose ZK VMs, developing custom circuits (e.g., for a novel DEX) remains complex versus Solidity. This matters for early-stage teams with limited cryptographic expertise.
pros-cons-b
FRAUD PROOFS VS. VALIDITY PROOFS
Validity Proofs: Pros and Cons
A technical breakdown of the two dominant security models for optimistic scaling. Choose based on your protocol's risk tolerance, capital requirements, and finality needs.
01
Fraud Proofs: Capital Efficiency
Lower operational cost: No expensive proof generation (SNARK/STARK) required. This matters for early-stage protocols where minimizing fixed costs is critical. The primary expense is the capital staked by validators for the challenge period (e.g., 7 days on Arbitrum One).
~$0
Proof Gen Cost
7 Days
Typical Challenge Period
03
Validity Proofs: Instant Finality
Mathematically guaranteed security: State transitions are verified by a cryptographic proof (ZK-SNARK/STARK) before acceptance. This matters for exchanges and payment networks where withdrawal delays are unacceptable, as seen with zkSync Era's < 1 hour finality vs. 7-day optimistic windows.
< 1 Hour
zkSync Era Finality
100%
Crypto. Guarantee
05
Fraud Proofs: User Experience Risk
Vulnerable to capital-intensive attacks: A successful fraudulent state transition must be challenged by a honest validator with sufficient bonded capital. This matters for high-value DeFi protocols where the cost of corruption may be lower than the potential exploit profit, creating systemic risk.
06
Validity Proofs: Prover Complexity
High engineering overhead & cost: Requires specialized infrastructure (provers, verifiers) and circuit development expertise (Cairo, Circom). This matters for teams without cryptography specialists, as proof generation costs (e.g., ~$0.10-$1.00 per tx) are passed to users.
$0.10-$1.00+
Est. Proof Cost/Tx
CHOOSE YOUR PRIORITY
Decision Framework: When to Choose Which Model
Fraud Proofs for Security
Verdict: The conservative, battle-tested choice for high-value assets. Strengths: Offers cryptoeconomic security backed by a large, decentralized validator set (e.g., Optimism, Arbitrum). The "challenge period" (typically 7 days) provides a robust window to detect and dispute invalid state transitions, making successful attacks extremely costly. This model inherits the security assumptions of its underlying L1 (like Ethereum). Trade-off: The long finality period (1 week+) is the price for this security, creating capital inefficiency for cross-chain withdrawals.
Validity Proofs for Security
Verdict: Offers mathematically guaranteed, near-instant finality, ideal for applications requiring strong, fast security. Strengths: Uses ZK-SNARKs/STARKs (e.g., zkSync Era, Starknet, Polygon zkEVM) to generate cryptographic proofs that state transitions are valid. Security is based on computational hardness, not game theory. Finality is achieved in minutes or hours, not days. Trade-off: The trust model shifts to the correctness and integrity of the relatively complex proof system and prover network. The technology is newer and less battle-tested than fraud proofs at scale.
FRAUD PROOFS VS VALIDITY PROOFS
Technical Deep Dive: Mechanism and Assumptions
This section dissects the core cryptographic and game-theoretic assumptions behind the two dominant scaling security models, providing a framework for architects to evaluate trade-offs between security, cost, and decentralization.
The core difference is the default state of trust. Fraud Proofs (FP) assume a new state is valid unless proven fraudulent, requiring active monitoring. Validity Proofs (VP) require cryptographic proof (like a zk-SNARK) that a state transition is correct before it is accepted, enabling trustless verification.
- Fraud Proofs (Optimism, Arbitrum): Use a challenge period where watchers can dispute invalid state roots.
- Validity Proofs (zkSync, StarkNet): Generate a succinct proof verified on-chain, providing instant finality. This creates a trade-off between operational overhead (FP) and computational intensity (VP).
verdict
THE ANALYSIS
Final Verdict and Strategic Recommendation
A data-driven conclusion on selecting the optimal proof system for your blockchain's security and performance needs.
Fraud Proofs, as implemented by Optimism and Arbitrum, excel at minimizing on-chain costs and maintaining EVM equivalence because they only compute and verify state transitions when a challenge is raised. This results in lower fixed costs for L2 operators and a smoother developer experience. For example, Arbitrum One processes over 500K transactions daily with an average fee under $0.10, showcasing the model's efficiency for high-volume, general-purpose dApps.
Validity Proofs, championed by zkSync Era and StarkNet, take a fundamentally different approach by requiring a cryptographic proof (ZK-SNARK/STARK) for every batch. This results in a trade-off: higher computational overhead and specialized tooling (e.g., custom languages like Cairo) in exchange for instant, mathematically guaranteed finality and superior data compression. This allows zkEVMs to achieve higher theoretical TPS and stronger security assumptions, as the underlying L1 only needs to verify a single proof.
The key trade-off is between cost-structure and security finality. If your priority is minimizing operational cost, maximizing developer accessibility, and scaling existing Solidity dApps with minimal friction, choose a Fraud Proof system like Arbitrum Nitro or Optimism Bedrock. If you prioritize cryptographic security guarantees, instant withdrawal finality (no challenge period), and are building a new application that can leverage custom VMs for maximal scalability, choose a Validity Proof system like zkSync Era or Polygon zkEVM. The landscape is evolving, with hybrid models like Arbitrum BOLD emerging to blend the best of both worlds.
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