NFT based warranty implementation on Blockchain by Tomp Comders

To run the backend [The backend will deploy the contract]

pip install -r requirements.txt
cd backend
brownie run scripts/app.py --network polygon-test

To run the refuel bot

cd backend
brownie run scripts/need.py --network polygon-test

To run the frontend

cd frontend
npm i
npm start

Introduction

An efficient approach to prove ownership of a product and claim its warranty has been developed and deployed as a web application. The application consists of three parts, frontend, backend, and smart contract. The smart contract has been deployed on the polygon-mumbai testnet. The application has been designed to cater to customers and brands with no knowledge of blockchain.

Problems Faced

1. Decaying an NFT automatically in the blockchain is not possible, some external trigger is necessary.
2. Paying gas prices by users can be hectic owing to the fact that they don't have expertise in blockchain.

Features

1. Login/Signup for customers and brands
2. Add to cart and buy option for customers
3. Purchase history for customers
4. Approve option for brands to create and transfer the NFT warranty using the serial number printed on the physical product and warranty validity months.
5. Transfer warranty to another customer
6. Transfer history of each warranty
7. Warranty data of a token_id (warranty id)
8. Owner verification by the brand during warranty claim

Basic Approach

Upon every signup, a new account address is created for the user. The private key associated with the address is stored in the app and not disclosed to the user.

Buying and selling procedure

The customer adds items to the cart and clicks on buy. This sends an approval request to the brand. While approving, the brand has to enter the serial number of the product that is being sold along with the warranty months. This mints the warranty NFT and

transfers it to the customer. This can be seen in the customer purchase history and present warranties.

Product verification by the customer

The customer can verify the authenticity of the product in two ways:

1. by accessing the transfer history of the warranty and verifying if the first account is of the brand.
2. by matching the serial number in the warranty with the serial number printed on the physical product.

Transfer of warranty by customer

The customer can transfer the warranty to another person via his/her account address. The recipient again can then check the transfer history to verify the original brand of the company and also match the product serial number.

Warranty claim

The customer can claim the warranty through an e-mail mentioning the warranty id and account address to the brand from the registered mail id. The brand can then verify the owner as well as the serial number of the product.

Warranty decay

The warranty decay has been achieved by a checkExpiry function in the smart contract. The time of the first call is noted in the blockchain and then every time the warranty is transferred, the checkExpiry function is invoked to validate the warranty. If the validity is over, the warranty would be burnt. This function can be invoked at other endpoints also, but it has been set at only one endpoint to reduce the cost due to the gas fee. Once the warranty is burnt, it does not appear in the customer’s “present warranties” section and the transfer history of such warranty ends at address0.

Getting around gas fee

Since the new account would have zero matic, after every signup, the account address is added to a table “ Needs”. This table is being constantlymonitored by a refuel bot that sends matic to the account addresses in need. The bot uses the main account as a Matic source. Similarly, after every transaction, a function check_need is executed that checks the balance and adds the account to the table if the balance is less than a

certain threshold. The present amount of matics in an account has been normalized to the energy that varies between zero and one. If the energy is below 0.5, the customer is warned that some transactions might not happen and is advised to wait till the refuel bot refuels his/her account.