Cipherbid - Confidential Sealed Bid Auctions
The first procurement auction where fairness doesn’t require trust. Every bid is encrypted end to end. The chain computes the winner on ciphertext, and only the winning bid is ever revealed very losing bid stays encrypted forever.
Built on Zama FHE for the Zama Developer Program (Mainnet Season 3 Builder Track, “Composable Privacy”).
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Live app:
https://cipherbid-one.vercel.app/ -
Verified contract (Sepolia):
https://sepolia.etherscan.io/address/0xdA2f411C9dc26dB3412b77829efAbc336666C54B#code -
Network: Ethereum Sepolia testnet
The problem
On a normal blockchain, every bid in an auction is public the moment it’s submitted. That breaks sealed bid auctions, the format used across real procurement, where bidders must commit without seeing each other’s numbers. Zero knowledge proofs can hide a single value, but they can’t compute over a growing pile of encrypted bids to determine a winner. Fully Homomorphic Encryption (FHE) can and it’s composable, which is the whole point of Season 3.
How it works
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Bid blind. Each bidder encrypts an amount client-side in the browser. The ciphertext goes on-chain; the number never does.
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Compare encrypted. The contract tracks the highest bid using FHE comparison (
FHE.gt+FHE.select) , computing on data that stays encrypted throughout. While bidding is open, no one . not even the auctioneer can see any bid or who’s leading. -
Reveal only the winner. After the auctioneer finalizes, only the winning bid is decrypted, to the authorized party. Every losing bid stays sealed.
Roles: bidders are anyone (no pre-registration); the auctioneer is the deploying wallet, the only address allowed to finalize and decrypt the winner.
Learn more about Cipherbid here: https://x.com/Dsgnrayo/status/2073365499505987628