ImpayQ: Core Noir Contracts

This repository contains privacy-enabled smart contracts written in Noir for the Aztec Network, implementing a payment system with merchant management and bundled token transfers.

Overview

ImpayQ is a privacy-focused payment system built on Aztec Network that allows:

• Merchant management and token assignment
• Bundled token transfers (both public and private)
• Token exchange with authorization mechanisms
• Secure account management

The system leverages Aztec's privacy features to enable confidential transactions while maintaining the flexibility needed for a modern payment infrastructure.

Contract Architecture

Merchants Contract (merchants.nr)

The Merchants contract manages merchant registration and token assignments:

• Admin Management:

  • constructor(admin): Initializes the contract with an admin address
  • set_admin(new_admin): Allows the current admin to transfer admin rights

• Merchant Operations:

  • add_merchant(merchant, token): Associates a merchant address with a specific token
  • get_token(merchant): Returns the token address associated with a merchant

Bundler Contract (main.nr)

The Bundler contract enables bundled token operations and exchange functionality:

• Token Bundling:

  • send_tokens_public(to, reward_token, stable_token, stable_amount, reward_amount): Sends both stable and reward tokens in a single public transaction
  • send_tokens_private(to, reward_token, stable_token, stable_amount, reward_amount): Same functionality as above but for private balances

• Token Exchange:

  • exchange_tokens_public(from, stable_token, reward_token, stable_amount, reward_amount, nonce): Exchanges stable tokens for reward tokens using public balances
  • exchange_tokens_private(from, stable, reward, stable_amount, reward_amount, nonce): Same as above but for private balances

• Authorization Management:

  • cancel_stable_authwit(inner_hash): Cancels an authentication witness for stable token
  • cancel_reward_authwit(inner_hash): Cancels an authentication witness for reward token

Account Contract (account/accounts.nr)

The SchnorrHardcodedAccount contract implements secure authorization using Schnorr signatures:

• entrypoint(app_payload, fee_payload, cancellable): Main entrypoint for account operations
• verify_private_authwit(inner_hash): Verifies private authentication witnesses
• is_valid_impl(_context, outer_hash): Implements signature verification using a hardcoded public key

Key Features

1. Privacy-Preserving Transactions: Both public and private methods for token transfers and exchanges
2. Authorization Witness (AuthWit): Secure delegation of transaction authority using cryptographic proofs
3. Bundled Operations: Multiple token operations in a single transaction, improving UX and reducing fees
4. Admin-Controlled Merchant Registry: Centralized management of merchants and their tokens

Dependencies

The project relies on the following Aztec Network packages:

• aztec: Core library for Aztec contracts
• authwit: Authentication witness functionality
• token: Standard token contract interface

Development

This project uses Nargo (Noir's package manager) for dependency management and compilation.

Prerequisites

• Install Nargo
• Familiarity with Aztec Network

Building and Testing

# Navigate to the contract directory
cd corecontracts

# Build the contracts
nargo build

# Test the contracts
nargo test

Deployment

These contracts are designed to be deployed on the Aztec Network. Refer to the Aztec documentation for detailed deployment instructions.

License

This project is licensed under the terms provided in the LICENSE file.

Contributors

• ImpayQ Team