TrustDrop Protocol
Fair exchange for encrypted files
TrustDrop is a protocol for exchanging encrypted files without relying on seller promises. It combines on-chain escrow, zero-knowledge proof verification, data availability checks, and buyer recovery logic into one exchange flow.
Guarantees
Escrowed payment
Buyer payment is locked in an exchange channel until the exchange reaches a valid closing path.
Proof-backed fulfillment
Seller fulfillment is tied to VSS and VDD verifier contracts rather than a plain off-chain claim.
Buyer recovery
The buyer can recover the encrypted asset using wallet-derived or manually supplied purchase secrets.
Core Components
| Component | Role |
|---|---|
ExchangeHub | Creates channels and emits canonical marketplace events. |
ExchangeChannel | Stores sales, pending exchanges, fulfillment state, and exchange closing logic. |
| VSS | Verifiable Secret Sharing path for buyer access to the data key. |
| VDD | Verifiable Data Delivery path for checking that the delivered encrypted data is recoverable as the listed file. |
| Oracle | Reports the current prototype's storage-side read signal used by settlement checks. |
Protocol Structure
TrustDrop separates payment logic from proof logic. The contracts hold funds and record exchange state. The zk programs prove the parts that the chain cannot cheaply check directly.
| Layer | What it does |
|---|---|
| Contracts | Maintain sales, purchases, pending exchanges, settlement, and buyer protection conditions. |
| VSS zk program | Checks the key-sharing step that lets the buyer recover the asset key. |
| VDD zk program | Checks the delivery step that ties the encrypted delivered data to the listed file. |
| Off-chain services | Generate proofs, publish encrypted assets, index events, and run the prototype oracle path. |
Applications
Fair File Marketplace is the first buyer-facing application built on TrustDrop. It is an application of the protocol, not the protocol itself.