PayByteCoin

A payment platform powered by blockchain.

Login Page

Main Dashboard - Profile, Transfer and Pending Transactions sections

Blockchain section in Dashboard

Expanded Block - Details within Block Header and Transactions are shown

Transaction Records section - All completed transactions recorded in Blockchain shown

Setup

• Firebase API Key

  • Setup a Firebase & Firestore Project
  • Copy API Key from (Project Overview > Project Settings > Add App (WEB) > Firebase Configuration)
  • Paste API Key to the following field under firebase.js

    const firebaseConfig = {
        apiKey: "",
        authDomain: "",
        projectId: "",
        storageBucket: "",
        messagingSenderId: "",
        appId: "",
        measurementId: ""
    }; 
    

  • Collections & Documents under Firestore do not need to be configured - except for Blockchain as Genesis Block has to be statically configured
    
    

• Node Modules

  • Install npm packages under package.json & package-lock.json

    cd .\frontend\
    npm i 
    

  • If npm install does not work, the following modules have to be installed manually
    • firebase
    • material ui/lab
    • material ui/material
    • material ui/icons-material
    • fontsource/roboto
      
      

• Blockchain

  • Two copies of the Blockchain are kept seperately in backend blockchain.csv & frontend (in Firestore)
    • backend
      • Check that first line of blockchain.csv has Genesis Block

        424cdcd9228886022373b5868f450863b84099a39f464d...
        

      • Change to another Block (Hexadecimal Format && len(Genesis_Block) > 64) only if you wish to
      • Check that there is empty newline after each block in order for crytodome.py to read and write to blockchain.csv file
    • frontend
      • Configure Firestore collection (Firebase Console > Firestore Database > Start Collection)
        • Parent Path: /
        • Collection ID: blockchain
      • Add Document - For Genesis Block
        • Document ID: Auto-ID
        • Fields
          • difficulty (number): 0
          • merkle_root_hash (string): "null"
          • mining_datetime (string): "18/11/2022, 12:00:00" - set to earliest point of datetime before any other blocks
          • new_block_hex (string) - input hexadecimal string of Genesis Block here
          • nonce (number): 0
          • previous_block_hash (string): "null"
          • transactions (array) - leave this array empty
            
            

• Virtual Enviroment

  • Tested and Developed on Python 3.10.6
  • Create venv

    •   cd .\backend\
        python -m venv venv
      

  • Start venv

    •   .\venv\Scripts\activate
      

  • Pip install

    •   pip install -r requirements.txt
        /OR/
        python -m pip install -r requirements.txt
      

  
  
  

Run PayByteCoin

• Backend

  •   cd .\backend\
      .\venv\Scripts\activate
    
      python app.py
      /OR/
      flask run
    

• Frontend

  •   cd .\frontend\
      npm start
    

• React Webpage will be hosted on http://localhost:3000/

  • Create New Account
    • Enter Username, Email, Password
      • Public-Private Key pair will be generated for User once registered
      • User's credentials are added to Firebase Authentication
      • User is added to 'users' collection in Firestore Database
    • Ideally there will a admin account
      • Byte Coin can be statically added to this admin account's accountBalance (as no Mining Rewards are given, only way to "introduce" new coins to the economy)
      • Once added, Admin can freely transfer Byte Coins to other users
        
        

PayByteCoin Usage

• Password of account needs to be inputted for a transaction (making a transfer of ByteCoin)

  • password of user's account is used to encrypt user's private key
  • user's decrypted private key is needed to sign a transaction
  • Note: wrong password entered will cause an error, transaction will fail
    
    

• Minimum Number of 2 Pending Transactions to mine a new block

  • Due to calculation of Merkle Root Hash
  • Enforced in Frontend
  • No Maximum Limit of Number of Transactions implemented (but computation time & python's recursion limit should be considered)
    
    

Additional Notes / Improvement Points

• Double Spending Issue

  • Possibility of Double Spending -> Leading to negative balance in account balance
  • Eg Alwin has 100 Bytecoins, he sends Bob 100 Bytecoins in one transaction (transaction A)
  • transaction A has not been mined to a Block
  • ALwin sends Alice 50 Bytecoins in another transaction (transaction B)
  • transaction A & transaction B are mined into a new Block and Block is added to Blockchain
  • Alwin has double-spent, and now has -50 Bytecoin account balance
    
    

• Cloud Firestore storage of datetime objects

  • Currently transaction and mining datetime is generated by backend using python datetime library, and stored as a sting ("%d/%m/%Y, %H:%M:%S" format) in cloud firestore
  • May lead to ordering errors when fetching pending transactions/blocks in blockchain/transaction records as documents are ordered by their datetime string (eg "01/01/2023, 00:00:01" will be ordered higher than "31/12/2022, 23:59:59" even though the latter is earlier)
  • Solution: store datetime as a datetime object in firestore, which itself needs to be generated in frontend, whenever a new transaction/block is generated