# WiP: NightMarket

A zero knowledge marketplace for Dark Forest coordinates.
A 0xParc Learning Group project - work in progress.
## Quicklinks
- [Spec & Brainstorm notes](https://hackmd.io/xrXO2QKeRJWY6WApxRrroQ)
- [Demo slides](https://docs.google.com/presentation/d/1Dk9gZJF_GiitnknPJThJDwokEA1zd0ncwr6Jqawwtq0/edit?usp=sharing)

## Quickstart
- Install: `yarn install`
- Test circuits: `yarn circom:test`
- Deploy circuits: `yarn circom:prod`
- Compile contracts: `yarn sol:compile`
- Test contracts: `yarn sol:test`
- Deploy contract: export `XDAI_PRIVATEKEY`, then `yarn sol:deploy`
- Run plugin server: `yarn app:dev`
- Deploy plugin: `yarn app:build`

## Directory
- `/circuits/list`: Circuits for generating a coordinate listing
- `/circuits/sale`: Circuits for fulfilling a sale to buyer
- `/circuits/utils`: Shared utility circuits
- `/circuits/test`: Circuit unit tests
- `/client`: Shared helpers and circuit files
- `/client/plugin`: DF plugin, a 100% frontend implementation
- `/contracts`: Contract and verifier code

## Spec
- Sellers list any valid Dark Forest coordinates at a fixed price
- Multiple buyers can purchase these coordinates
- Sellers can attest their planet has certain biomes

## Circuit Design
#### LIST
Prove: Seller has (x,y) coords, and sell a `KEY` used to encrypt it
- `hash(XY,PLANETHASH_KEY) ==> valid_coord` // commit to a valid data/coordinate
- `ENCODE(XY, KEY)` // encrypt data with key
- `hash(KEY)` // commit to the secret key

#### SALE
Prove: Seller encrypted `KEY` with a `SHARED_KEY` from an (offline) ECDH key exchange with Buyer
- `SHAREDKEY <== ecdh(sellerPrivKey, buyerPubKey)`
- `ENCODE(KEY, SHARED_KEY)`
- `hash(KEY)` // commit to the original key
- `hash(SHAREDKEY)` // commit to the same shared key

#### ENCODE
Scheme: Encryption using a 5-wide Poseidon in SpongeWrap with (0, len=2, Kx ,Ky , N) as input.
- List: 
	- message[0] = planet x coordinate
	- message[1] = planet y coordinate
	- key[0] = left half of `key` being sold
	- key[1] = right half of `key` being sold
- Sale:
	- message[0] = key[0]
	- message[1] = key[1]
	- key[0] = k_x of shared key
	- key[1] = k_y of shared key

## Escrow Contract
- `list(..., listProof, price, escrowTime)`: sellers can list valid coordinates and vary `price` & `escrowTime` for better buyer UX. (Note: it prevents malicious-buyer race condition). Sellers can sell a single coordinate to multiple buyers.
- `delist(...)`: sellers can delist coordinates if they plan to be offline. This helps with seller reputation as this zk marketplace has to be interactive.
- `ask(...)`: buyers can create (duplicate) orders on listings and lock up a payment for `escrowTime` blocks.
- `sale(..., saleProof)`: sellers can close a sale and fulfill a buyer order.
- `refund(...)`: anyone can refund buyers deposit if seller delists or if the `escrowTime` lockup is over.

## Plugin (IN PROGRESS)
**Implementation note:**
DF plugins are esbuild bundled then served as a single JS file, which is limiting given the current SNARKs/circom stack. So the following was done to make snarks possible, purely in browser.
- NPM `ffjavascript-browser` shim (stub native Node deps like `os` `stream`)
- Rolluped NPM snarkjs into a `helpers/snarkjs.js` (DF game currently has older version in /Public)
- `fullprove` fetches an external `raw.githubusercontent` URL (plugin builders can't write files to server)

## Benchmarking
- `List` circuit constraints: 23850
- `List` smart contract call: 533k gas
- `Sale` circuit constraints: 3421
- `Sale` smart contract call: ~TBA gas 

## Warning
The circuits and smart contracts written for this marketplace has not been audited, use at your own risk.

## Danger
Plugins are evaluated in the context of your game and can access all of your private information (including private key!). Plugins can dynamically load data, which can be switched out from under you!!! Use these plugins at your own risk.

You should not use any plugins that you haven't written yourself or by someone you trust completely. You or someone you trust should control the entire pipeline (such as imported dependencies) and should review plugins before you use them.

## Acknowledgements
- 0xParc for study group
- [DF plugins](https://github.com/darkforest-eth/plugins)
- [DF Circuits](https://github.com/darkforest-eth/circuits)
- [EthMarketPlace](https://github.com/nulven/EthDataMarketplace)
- [Maci](https://github.com/appliedzkp/maci/)
- [Poseidon Encryption](https://github.com/iden3/circomlib/pull/60), [Paper](https://drive.google.com/file/d/1EVrP3DzoGbmzkRmYnyEDcIQcXVU7GlOd/view)
- [DF plugin](https://github.com/Bind/my-first-plugin)
- [Darksea Market](https://github.com/snowtigersoft/darksea-market)
- [Artifact Market](https://github.com/dfdao/artifact-market/)
- [Play to earn](https://github.com/projectsophon/df-play-to-earn)