Phylax and Titan Bring Circuit Breakers to Ethereum
Titan, which assembles about half of Ethereum's blocks, now checks transactions against apps' own safety rules before they settle.
Security startup Phylax launched a block-level checker with Titan Builder: if an attacker tried to drain an app like Lighter with a withdrawal its rules don't allow, Titan would leave just that transaction out of the block it's building.
What's the Scoop?
The Rules: Apps write their own limits, like Phylax's example of a vault capping any single withdrawal at 50% of its assets. So attackers can't just route around Titan, protected functions can be set to fail in blocks no participating builder has checked.
The Reach: Over the past day, Titan built ~53% of blocks that validators accepted from outside builders instead of assembling themselves, per tracker relayscan. Founder Odysseas Lamtzidis named Lighter and Derive as first customers, with "almost 1 billion under protection."
The Track Record: Ethereum L2 Linea has offered Phylax as an opt-in since January. Enrollee Denaria still lost ~$166K on April 5 to an accounting bug: its only rule blocked bad debt, which the attack didn't create, so the check never fired.
The Limits: Overall, it’s a tripwire, adding to audits but only stopping outcomes an app wrote a rule for. Further, Titan only runs the checks so the apps must write or change their rules over time. There's no cryptographic proof yet that the checks ran, so users take the builder's word, per Phylax's docs.
David Christopher
David is a writer/analyst at Bankless. Prior to joining Bankless, he worked for a series of early-stage crypto startups and on grants from the Ethereum, Solana, and Urbit Foundations. He graduated from Skidmore College in New York. He currently lives in the Midwest and enjoys NFTs, but no longer participates in them.
