How a sealed-bid auction works
The mechanism is old and simple; governments have sold bonds and oil leases this way for a century. The auctioneer announces what’s for sale, every bidder hands in one bid in a sealed envelope, and the envelopes are opened together. Best bid wins and pays what it bid (a first-price sealed auction). What makes it interesting is what bidders can’t do:
In an open auction the winner only ever pays slightly more than the second-best bidder was willing to. In a sealed auction a bidder who shades their offer risks losing outright to someone they couldn’t see, so competitive pressure pushes every bid toward the bidder’s real limit.
Why this fits DeFi trading
Public blockchains leak information by default, and most trading attacks are built on that leak. A swap in the public mempool can be sandwiched before it lands. A visible quote can be undercut at the last moment by a competitor who never intended to price the trade honestly, only to beat whoever showed their hand first. A sealed-bid auction removes the channel those attacks need. The order never touches a public mempool, so there’s nothing to sandwich. Bids are private, so there’s nothing to undercut by a tick; a solver that wants the order has to outbid rivals it cannot observe. This is the mechanism behind the MEV protection that Why Delta promises.How Delta runs the auction
Every Delta order is auctioned in rounds. One round looks like this: Three details do most of the work:- A bid is a commitment, not a quote. Solvers don’t reply with a number; they reply with the exact calldata the protocol can execute and the amount that calldata should deliver. There’s no second look and no renegotiation after seeing the field.
- Bids are ranked by simulation, not by claim. Before picking a winner, the order server simulates every bid against current chain state and ranks bids by what they actually produce. A solver that promises a great price but whose calldata reverts or underdelivers doesn’t win.
- Surplus flows back. When the winning fill beats the quoted price, the user receives the improvement; a portion is split between the integrator and the protocol. Solvers compete on execution quality, and users capture it.
What stops a malicious solver
Each layer of the auction closes a different attack:
The pattern across all five: the auction never has to trust what a solver says. Bids are verified by simulation before the award, and the user’s floor is verified by the contract after it.
Related pages
- Portikus Network — the intent infrastructure behind these auctions.
- How it works — where the auction sits in the full Delta flow.
- Why Delta — what the auction buys you as an integrator: gasless, MEV-protected swaps.