Project Overview

This application is designed to demonstrate the use of Merkle Trees for efficient and secure verification of data. In this scenario, the system manages a list of names eligible to receive a gift. The client, acting as a prover, needs to confirm to the server (the verifier) that a particular name is on the list using a Merkle Tree-based proof.

The project is an exemplary implementation of a Merkle Tree in a client-server architecture, where the client generates a proof for a name, and the server verifies this proof against a pre-generated Merkle Root to confirm the name's presence on the list.

Base Project: https://github.com/alchemyplatform/GiftList

My Approach

I preferred to calculate the Merkle proof on the client-side as the size of the Merkle Tree was not huge, but another option might be to calculate the proof on the server (node) in order not to expose the whole tree to the clients, and allow lightweight clients to operate smoothly. A hybrid approach might as well be adhered. Project size and requirements are key factors so as to pick a design approach.

Repository Structure

• client/index.js: The client-side logic for generating Merkle Tree proofs for a given name.
• server/index.js: The server-side logic for verifying the proof provided by the client.

/utils: Contains the necessary utilities for Merkle Tree operations.

• niceList.json: A list of names eligible for gifts. Feel free to modify this list as needed.
• MerkleTree.js: A utility module for creating and handling Merkle Trees.
• verifyProof.js: Utility function for verifying Merkle Proofs against a given Merkle Root.
• example.js: Demonstrates how to generate a root, a proof, and verify a value using these utilities. Run it using node example.js.

How It Works

Client (Prover): The client takes a name and generates a Merkle Proof using MerkleTree.js. This proof is then sent to the server.

Server (Verifier): Upon receiving the proof from the client, the server uses verifyProof.js to check whether the provided name is in the Merkle Tree corresponding to the pre-generated Merkle Root. If the verification is successful, the server acknowledges that the name is on the list.

Running the Application

Install Dependencies:

• Ensure you have Node.js installed.
• Install necessary Node modules by running npm install in the project's root directory.

Running the Server:

Start the server by executing nodemon server/index

Running the Client:

Run the client script with node client/index