Blockchain

A Simple Blockchain By Hawshemi

Live Website: https://blockchain.up.railway.app

Video Demo: https://youtu.be/iEPosDOyiPg

This project submitted at CS50 Final Project.

Website Features

• Registration and Logins with password hashing.
• Password Validation Check
• Handle Errors with codes.
• Check the Blockchain integrity.
• Make a Transaction on the blockchain.
• Review the Transaction History Table.
• Ability to export to XLS.
• Ability to Reset the blockchain.
• Logout

The Blockchain

• Stores the block information on a JSON file.
• Read the JSON and view to blocks.
• Validate the blocks using their hash.
• Store the JSON and blocks in a Database.

Database and Tables

The database consists of 3 tables:

• The users containing userid, username and hashed password.
• The sequence that stores the number of users and transactions.
• The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.

Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.

Tech Stack

The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.

How to run

This repo is hosted on blockchain.up.railway.app.

For Local Run:

0. Clone the GitHub project.

1. go to main.py and at the end of the file, edit:

   if __name__ == "__main__":
       app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))
   

   To:

   if __name__ == "__main__":
       app.run(debug=True)
   

2. Create a virtual environment of python and then run:

   pip install -r requirements.txt
   

   And then:

   python main.py
   

How this works?

First, we have a blockchain folder which contains the blocks JSON.

The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.

hashlib.md5(content).hexdigest()

When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.

In main.py, the flask app would run, and all the routing for HTML.

For more information of how blockchians work: https://www.investopedia.com/terms/b/blockchain.asp