Dave: Not the Hero We Want, But the Hero We Need | HackerNoon

Security has long been a watchword of crypto. Without sophisticated systems, algorithms, and processes that are fiercely resistant to attack, the industry wouldn’t have grown to a $3 trillion + market cap in less than twenty years. Stroll along the first line of defense and you’ll inevitably encounter fraud-proof systems, mechanisms that safeguard against invalid state transitions by letting anyone challenge and prove dishonesty. In the case of Layer-2 rollups, which bundle thousands of off-chain transactions into a single on-chain post, fraud proofs are essentially the Praetorian guard.

With rollups periodically committing states to the mainnet that are then rubber-stamped with fraud proofs or optimistically assumed legitimate (whereafter challenges can be made and fraud proofs employed), such algorithms need to be robust. Particularly as there’s now over $30 billion of value locked in them. And yet the vulnerabilities of fraud proofs are multitudinous, making them a veritable ticking time-bomb in the L2 landscape.

Hence why Cartesi has designed a new permissionless, interactive fraud-proof system called Dave. Although its name makes it sound like a nondescript regular propping up the bar, Dave might actually be the answer to keeping that $30 billion TVL safe.

Optimistic Rollups: Scaling Ethereum, But at What Cost?

Let’s dive into Optimistic Rollups (ORs), the darlings of Ethereum’s scaling ecosystem. So-named because they pre-suppose off-chain transactions are valid (no fraud proofs needed upfront), these L2 protocols pride themselves on extending Ethereum’s throughput by up

to 100x.

With security tethered to Ethereum’s base layer, ORs post transaction results on-chain while processing batches off-chain. Of course, there needs to be a backstop to keep everyone honest, and it exists in the form of a challenge system – whereby batches can be contested within a stipulated time-frame via a fraud proof. In this way, security is maintained without the need for continual on-chain verification.

But here’s the rub: traditional fraud-proof algorithms have flaws. Quite a few, in fact. Not only is participation in dispute-resolution expensive but Sybil attacks – where attackers flood the system with fake identities – can overwhelm them. Moreover, the entire process is onerously lengthy, meaning a well-funded adversary, after a prolonged resource-exhaustion campaign, can claim victory. Successful Sybils are analogous to evil forces grinding down the noble but outmatched hero on the battlefield.

Cartesi’s Fraud-Proof Game Changer

The brain trust at modular blockchain protocol Cartesi couldn’t stand idly by and ignore the potentially fatal flaws of Optimism’s OPFP and Arbitrum’s BoLD. Instead, its bright minds developed Dave, intending it as a ‘public good’ for the Ethereum ecosystem. Designed to balance decentralization, security, and liveness and based on Cartesi’s Permissionless Refereed Tournaments (PRT) primitive, Dave is a bulwark against bad actors, one virtually impervious to Sybil attacks due to the fact that even one honest validator can enforce the correct state on-chain – regardless of how many adversaries mount an attack.

Dave’s secret sauce? A divide-and-conquer strategy that pits Sybils against each other, forcing them to implode while the honest validator encounters minimal opposition. The algorithm was created in such a way that launching a Sybil attack against it is exponentially costly for attackers, both in delay and resources, compared to what the honest actor must spend. A recent ethresear.ch post showed how Dave could thwart a 1 million ETH Sybil attack with just 7 ETH from an honest validator.

Another nifty feature of the system is the speed of its dispute resolution; disputes resolve within 2–5 challenge periods for any realistic Sybil count, keeping the network humming along nicely.

Unlike OPFP or BoLD, Dave lets (but doesn’t force) honest validators to cooperate trustlessly, acting as a collective without centralized trust. Because you don’t have to be a crypto whale to fight fraud, it empowers even small players to defend the integrity of rollups against whomever they come up against. In short, fraudsters’ attempts to game ORs are doomed to failure: Dave’s math makes manipulation a losing bet.

Cometh the Hour, Cometh the… Dave

Rollups aren’t an inconsequential offshoot of the crypto world, they’re now a pillar of it. As more value piles onto L2s and ORs, legacy fraud proofs need a re-do, analogous to the way a strong army must embrace new tech and future-proof its might by attracting fresh blood.

Dave could be the best solution, offering as it does Sybil resistance, rapid dispute resolution, and minimal resource demands for honest validators. Cartesi’s focus on application-specific rollups makes Dave a natural fit, extending Ethereum’s security while keeping L2s lean and mean.

**He might not be the hero we want, but now that he’s arrived, we should roll out the red carpet for Dave.
Don’t forget to like and share the story!