P2P Fiat-to-Crypto On-Ramp for Cardano

Trustless P2P on-ramp is a smart contract app that connects cryptocurrency sellers and buyers. A seller deposits funds into the smart contract and ask for a fiat payment. Once the payment is delivered, the buyer can generate a cryptographic proof and unlock the funds from the smart contract.

Prototype web-app can be tested at https://p2p.zkfold.io/

Web-app instructions

The app allows for "sellers" to post sell orders (crypto for fiat) and for "buyers" to choose and buy a sell order. The web-app contains four sections:

1. Wallet selector
2. Seller's panel
3. Listing of sell orders
4. Buyer's panel

A seller operates with sections 1, 2, and 3; the buyer with sections 1, 3 and 4.

Seller's panel

• Posting a sell order. The seller commits to a sell offer by filling the required fields and pressing the Sell Offer button. This prompts the seller to sign a message (needed to collect the seller's public key). Next, the seller presses button Submit Tx to sign and submit the transaction that sends the seller's offered crypto, together with the corresponding sell-offer's datum, to the p2p-onramp smart contract. The seller should take note of the OrderID associated to his/her offer.

• Cancelling a sell order. If after a while there is no buyer for the seller's offer, the seller can cancel the corresponding order by entering its OrderID and pressing the Cancel Order button. This allows the seller to recover the offered crypto. If a buyer has commited to the seller's offer, but has not deposited the fiat within the "claim grace period", the seller can go ahead and cancel the order.

Listing of sell orders

Press the Available sell orders button to refresh the list of available sell orders. Those that have a commited buyer are highlighted.

Buyer's panel

The buyer commits to a sell order by entering the corresponding OrderID and pressing the Sign Tx button. The corresponding submitted transaction updates the order with the buyer's pub-key-hash and a time-lock associated to the "claim grace period" for the buyer to deposit the fiat. Next, the buyer presses the Verify fiat button for the platfrom to "verify the fiat deposit" and generating the corresponding cryptographic signature. Finally, the buyer presses the Claim crypto button to claim the bought crypto.

Installation instructions

If you so desire, you can run the P2P-OnRamp web app locally.

Requirements

Compilation was tested with GHC 9.6.6 and Cabal 3.10.2.1. Other library requirements are described in this guide. Additionally, libpq-dev or postgresql need to be installed as otherwise an error suggesting missing pg_config can occur.

p2p-onramp server

To run the p2p-onramp server, execute:

cabal run p2p-server -- provider-config.json onramp-config.json

where

1. provider-config.json contains your configuration for network and provider. File maestro-config-TEMPLATE.json provides a template configuration.
2. onramp-config.json contains the P2P-OnRamp's configuration parameters. File onramp-config-TEMPLATE.json provides a guide for the platform's configuration.

Note: File onramp-config-TEMPLATE.json makes reference to files fiat.addr, fiat.vkey and fiat.skey. These can be generated with cardano-cli as usual:

cardano-cli conway address key-gen --verification-key-file fiat.vkey --signing-key-file fiat.skey
cardano-cli conway address build --payment-verification-key-file fiat.vkey --out-file fiat.addr --testnet-magic 2

The p2p-onramp server on this repository was written using the Atlas framework.

p2p-onramp client

The p2p-onramp frontend can be found here.

Test suite

A comprehensive test suite for the P2P-onramp smart contract can be found in directory ./tests. To run the tests, execute:

cabal test