Optimism devs tackle bad actors with fault-proof system testnet launch

The latest system will comprise three components, a fault-proof program, a fault-proof virtual machine and a dispute game protocol

article-image

gguy/Shutterstock modified by Blockworks

share

Ethereum scaling startup Optimism has published the first release of “fault-proof system alpha.”

Now available on the OP Goerli testnet, the system has three components: a fault-proof program (FFP), the code that executes the EVM; a fault-proof virtual machine (FPVM); and a dispute game protocol. 

The goal of these different systems is to work in tandem in an effort to challenge malicious activity on the Optimism network. Fault proofs are designed to prevent fraudulent activities or errors from being processed in rollup transactions. 

Optimistic rollups are “optimistic” in nature, as they assume transactions are accurate until proven otherwise. Fault proofs form an important security measure to ensure that false activities aren’t accepted on the network.

OP Labs CEO Karl Floersch told Blockworks in an interview that the fault-proof system builds off the Bedrock upgrade and is designed to set the stage for the project’s second stage of decentralization.

Upon launch, users will be able to participate in the dispute game protocol, but they are not incentivized to do so, Floersch explains. This is because the bonding design will not be added during the protocol’s testnet release but will be included ahead of the OP mainnet launch. 

A bond refers to the amount of money a sequencer must post on Ethereum in order to participate in network activities. If fraud is proven, the sequencer’s bond will be slashed and redistributed to verifiers. 

“The dispute game is indeed permissionless so that there can be multiple clients and multiple fault proofs that are all running in parallel,” Floersch said. “This does not mean that the system is bulletproof at the moment; we’re launching this testnet to get a bunch of eyes on the design. It is critical we get the community to understand how it works.”

Multiple players can participate in the dispute game, which will not be limited to 1v1. This design was to mitigate the potential of denial-of-service vectors in 1v1 games, where malicious actors could potentially challenge themselves and lead to deadlock or inaccurate resolutions. 

Path to decentralization

Fault proofs are a step in achieving a permissionless transition of information between a layer-1 and a layer-2. This means that an end user should be able to deposit their tokens into a layer-2 from a layer-1, and then withdraw their tokens from a layer-1 — without anyone being able to stop the process. 

It’s important to note that tokens directly deployed to a layer-2 do not have any dependencies on the fault-proof system, as there is no bridge back to the first network layer for those tokens. 

“This is critically important because [layer-1s] have the highest security and decentralization properties,” Floersch told Blockworks. “It also allows users to opt out of upgrades to the [layer-2].”

As it currently stands, every major layer-2 project has trusted parties who hold upgrade keys that can execute protocol upgrades, making it a primary point of centralization. This is because if upgrade keys were to be compromised, all deposited assets in the layer-2 protocol would be at risk.

“The goal of what we’re doing is that we’re drawing the fastest path to decentralization,”  Floersch explained. “And the prerequisite for that is multiple fault-proof implementations.”

OP Lab’s fault-proof system will be entirely open-source, and a bug bounty will be put in place, according to Floersch.


Get the news in your inbox. Explore Blockworks newsletters:

Tags

Decoding crypto and the markets. Daily, with Byron Gilliam.

Upcoming Events

Old Billingsgate

Mon - Wed, October 13 - 15, 2025

Blockworks’ Digital Asset Summit (DAS) will feature conversations between the builders, allocators, and legislators who will shape the trajectory of the digital asset ecosystem in the US and abroad.

recent research

Unlocked by Template (10).png

Research

Innovations on Aptos’ technical design through Raptr, Shardines, and Zaptos approach near-optimal latency and throughput by unlocking 100% utilization of network resources, with the capacity to settle 260k transactions per second with latencies less than 800ms. The original Move language was revamped with the launch of Move 2, supporting more expressivity in smart contract logic and a scalable ability to interact with high volume datasets. The ecosystem has benefitted from strong asset inflows, now hosting over $1.3B in stablecoins, $450M in bridged BTC, and $530M in RWAs. Activity in the Aptos ecosystem has grown notably over the past year, with monthly application revenue reaching ~$835k and monthly DEX volumes growing to over $5B, both at new all time highs.

article-image

Interchain Labs will focus on sovereign L1s and institutional demand, abandoning plans for smart contracts on the Cosmos Hub

article-image

Also, only three tokens have outperformed bitcoin so far this year: XMR, HYPE and SKY

article-image

The fund group has submitted proposals in recent months for other funds that would hold litecoin, solana, XRP, HBAR, Sui and others

article-image

Momentum’s back — BTC leads, risk assets follow

article-image

Ondo Finance’s acquisition of blockchain development company Strangelove follows its buy of Oasis Pro

article-image

Cryptocurrency and stock traders alike had a lot to unpack Wednesday