Blockchain-Based Decentralized Storage Design for Data Confidence Over Cloud-Native Edge Infrastructure

This project demonstrates a multi-step approach to securely store encrypted files, link their metadata on a private blockchain, and manage additional properties (e.g., attention/confidence labels) via a MongoDB-based service. It also includes a simple React front-end for uploading and retrieving files under specific rules. The project is based on Blockchain-Based Decentralized Storage Design for Data Confidence Over Cloud-Native Edge Infrastructure by Hannie Zang; Ho Kim; Jongwon Kim et al.

Overview

1. Private Blockchain (Ganache + Smart Contract)

• A local Ethereum-compatible blockchain using Ganache.

• A FileRegistry smart contract storing minimal metadata on-chain (version, timestamp, hash reference, owner).

2. Storage Backend (Node.js)

• A Node/Express service that encrypts files and stores them either locally or on IPFS.

• Exposes /store and /retrieve endpoints.

3. Metadata Database (MongoDB)

• Stores extended metadata (file location, access rights, attention/confidence labels).

• A Node.js/Mongoose service providing CRUD on metadata.

4. Front-End Demo (Vite + React + shadcn/ui)

• A basic React app to upload files with labels and retrieve them under the attention/confidence rule.

---

Step-by-Step Setup

1. Private Blockchain (Ganache)

1. Install Ganache:

npm install -g ganache

or download Ganache Desktop.

2. Start Ganache on http://127.0.0.1:8545.

3. Deploy the FileRegistry contract using Truffle or Hardhat:

truffle compile

truffle migrate --reset

2. Storage Backend (Node.js)

1. Install dependencies in storage-service/:

cd storage-service

npm install

2. blockchain.js references:

• Ganache URL: http://127.0.0.1:8545.

• Private Key: from an account in Ganache with enough ETH.

• Contract Address: from the deployed FileRegistry.

3. Run the server:

node app.js

or

npm start

The service listens on http://localhost:3000.

3. Metadata Database (MongoDB)

1. Install MongoDB or use Mongo Atlas.

2. In metadata-service/:

npm install

node app.js

or

npm start

3. Environment:

• Default connection is mongodb://127.0.0.1:27017/metadata_db.

• Exposes endpoints like GET /metadata/:fileId, POST /metadata.

4. Front-End Demo (Vite + React)

1. Install dependencies in frontend/:

npm install

npm run dev

2. The app will run at http://localhost:5173 (default Vite).

3. The front-end has:

• A simple upload form pointing to http://localhost:3000/store.

• A retrieval form pointing to http://localhost:3000/retrieve/:fileId.

---

Workflow

1. User selects a file in the front-end, provides label, attention, confidence.

2. The Front-End sends a POST /store to Storage Service.

3. Storage Service:

• Encrypts the file, stores it locally (or IPFS).

• Calls the Metadata Service to save extended properties (label, dataLocation, etc.).

• Calls the Blockchain (FileRegistry) to store minimal references on-chain (fileId, version, hash).

4. To Retrieve:

• The front-end calls GET /retrieve/:fileId.

• The storage service checks metadata, ensures attention >= confidence, and if allowed, decrypts and returns the file.

---

Testing

1. Upload with Postman or the React front-end:

curl -X POST -F "file=@test.pdf"  \

-F "attention=Always"  \

-F "confidence=Usually"  \

http://localhost:3000/store

2. Retrieve:

curl http://localhost:3000/retrieve/test.pdf --output test.pdf

or from the front-end retrieval form.