Privacy-preserving negotiation on Base
Concord - FHE Blind Negotiation
Concord lets two counterparties negotiate without disclosing their numbers. Offers are encrypted client-side, compared homomorphically, and only the settlement outcome is revealed - the losing side's position stays private forever.
- Year
- 2025
- Role
- Solo engineer - protocol design and frontend
- Focus
- Solidity, FHE, Next.js
Screenshots
Negotiation room - sealed offers held in escrow until both sides match.
Problem
Two parties want to reach a deal without leaking their reservation prices or leverage to each other.
Solution
Encoded offers as encrypted values, computed match logic over ciphertexts with FHE, and settled outcomes trustlessly via smart contract escrow.
Result
Deployed a working demo where matched deals settle automatically and unmatched offers reveal nothing.
What it does
- Client-side encryption of every offer
- Match logic evaluated over ciphertexts with FHE
- Smart-contract escrow with automatic settlement
- No reveal path for unmatched offers
- Next.js interface with wallet connection on Base
Scope of work
- Blind negotiation protocol design over encrypted offers
- Homomorphic match logic evaluated without decryption
- Escrow contract that settles matched deals automatically
- Next.js negotiation room with wallet connection on Base
Timeline
Weeks 1-2
Protocol design
Defined the offer encoding and the reveal rules for both sides.
Weeks 3-5
FHE circuits
Implemented comparison over ciphertexts and validated correctness.
Weeks 6-7
Escrow
Wrote the settlement contract and wired it to match results.
Week 8
Interface
Built the negotiation room and shipped the public demo.
Outcomes
Zero leak
Unmatched offers reveal nothing at all
Automatic
Matched deals settle straight from escrow
Live demo
Deployed and publicly testable on Base