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Document Verification with PoDSI

Seal It with PoDSI: Verifying Document Authenticity on Lighthouse SDK

Overview

This comprehensive guide will walk you through the steps to implement a Document Verification System using the Lighthouse SDK. This application allows users to upload important documents, which are then timestamped and stored immutably on the Filecoin network for verification purposes.

Prerequisites

  • Basic understanding of JavaScript and Node.js
  • Node.js and NPM: If not already installed, you can download and install them from here.
  • Lighthouse CLI: Installed globally on your machine. Install it via npm using the command:
    npm install -g @lighthouse-web3/sdk
  • API Key: Generate it using Lighthouse CLI or refer to the official documentation for more methods.

Introduction to Lighthouse

Lighthouse is a perpetual file storage protocol designed to merge the robust storage capabilities of IPFS and Filecoin with the adaptability of various blockchain networks. By enabling users to pay a one-time fee for long-term storage, it presents a cost-effective alternative to the recurring expenses tied to conventional cloud storage, striving to deliver a secure and decentralized storage solution.

Key Concepts

IPFS (InterPlanetary File System)

IPFS is a protocol designed to make the web faster, safer, and more open by replacing the traditional, location-based address system with content-based addressing. This means files and content are addressed by what they contain, not where they are located, ensuring decentralization and security.

Filecoin

Filecoin is a decentralized storage network that turns cloud storage into an algorithmic market. It facilitates the trading of excess storage space, allowing users to rent their extra space out, creating a decentralized market for data storage and retrieval.

PoDSI (Proof of Data Segment Inclusion)

PoDSI is a proof mechanism that confirms a specific piece of data is included and stored within the Filecoin network. It acts as a certificate of authenticity, verifying the existence, integrity, and timestamp of stored files.

Step-by-Step Implementation

Step 0: Getting your lighthouse API key Files-Lighthouse-storage:

  1. 1.
    Go on https://files.lighthouse.storage/ and Click on Login
  1. 2.
    Select any of the login method and perform verification steps
  1. 3.
    Click on API Key on the left side panel on the dashboard.
  1. 4.
    Insert name for your API
  1. 5.
    Copy the API Key

Step 1: Upload a Document

Use the Lighthouse SDK to upload a document to the Filecoin network.
import lighthouse from "@lighthouse-web3/sdk";
async function uploadDocument() {
const filePath = '/path/to/your/document.pdf';
const apiKey = 'YOUR_API_KEY';
const uploadResponse = await lighthouse.upload(filePath, apiKey);
console.log('File Uploaded, CID:', uploadResponse.cid);
}
uploadDocument().catch(console.error);

Step 2: Retrieve PoDSI (Proof of Data Segment Inclusion)

PoDSI certifies the existence and integrity of the document on the Filecoin network at a specific time.
import axios from "axios";
async function getPoDSI(cid) {
const response = await axios.get(`https://api.lighthouse.storage/api/lighthouse/get_proof?cid=${cid}`);
console.log('PoDSI:', response.data);
}
const cid = 'Qm...'; // Replace with the actual CID of your file
getPoDSI(cid).catch(console.error);

Step 3: Verify the Document

Verify the document's authenticity using its PoDSI.
function verifyDocument(poDSI) {
const { pieceCID, dealInfo } = poDSI;
if (!pieceCID || !dealInfo || dealInfo.length === 0 || !dealInfo.every(deal => deal.dealId && deal.storageProvider)) {
console.error('Verification Failed');
return false;
}
console.log('Document Verified:', pieceCID);
return true;
}
getPoDSI(cid).then(verifyDocument).catch(console.error);

Step 4: Download the Document (Optional)

Enable document retrieval using the document's CID.
async function downloadDocument(cid) {
const response = await axios({
method: 'GET',
url: `https://gateway.lighthouse.storage/ipfs/${cid}`,
responseType: 'stream',
});
// Implement logic to save the file stream to a local file
}
downloadDocument(cid).catch(console.error);

Conclusion

Well done! You've successfully implemented a system to verify document uploads using PoDSI and the Lighthouse SDK on the Filecoin network. This base setup can be tailored to accommodate specific needs or integrated with additional features. Dive deeper and continue enhancing your application's functionality!