Bcoin

• A simple implementation of a cryptocurrency in python made on top of blockchain technology.
• It is a simple working blockchain cryptocurrency and to be used as an educational material.

Blockchain

• A blockchain is a digital record of transactions. The name comes from its structure, in which individual records, called blocks are linked together using cryptographic principles in single list, called a chain.

• The blockchain network has no central authority.

• The information in it is open for everyone to see.

• Main Properties of blockchain for its popularity

  • Decentralization
  • Transperancy
  • Immutability

Take a look at the simple implementation of blockchain. Bcoin is built on top of this blockchain implementation.

Find more information in the original paper.

Take a look at the original bitcoin repository.

Requirements

• Python 3.x
• Flask
• Requests
• Postman

How to run it

Install Python 3.x and Postman in your local machine.

Install flask and requests through pip(python package installer) in your command prompt.

• Example

  pip install flask
  

Clone this repository https://github.com/bharathikannan1311/bcoin.git

• After cloning just go into the folder and run the bcoin.py file.

  • Example

  C:\Users\BHARATHI KANNAN.N\Desktop\bcoin>python bcoin.py
  * Serving Flask app "bcoin" (lazy loading)
  * Environment: production
  WARNING: This is a development server. Do not use it in a production deployment.
  Use a production WSGI server instead.
  * Debug mode: off
  * Running on http://0.0.0.0:5001/ (Press CTRL+C to quit)
  

• Then open your postman desktop app and test your application.

  • Example
  

How this code works

bcoin.py

• Running the file will create a node. It will create a genisis block at first and then you can add transactions and mine the block. As a reward for this you will receive some coins.
  • Consensus Mechanism - Proof of work

bccoin_node_5001.py
bccoin_node_5002.py
bccoin_node_5003.py

• Running these files seperately will create three nodes in your local machine.

• Connect these nodes using the POST request in postman.

  

Adding Transactions

• Transaction can be added as a post method in postman.

  

Mining the block

• We can then mine the block and we will be rewarded with some bcoin.

  

Updating the nodes

• Since it is a distributed system if one block mines and update the chain all other nodes should update their chain.

• We will replace the chain with the longest valid chain by checking all other nodes otherwise we will not update.

  

Bcoin Blockchain

• Blockchain after mining 5 times will be

{
  "chain": [
    {
      "index": 1,
      "previous_hash": "0",
      "proof": 1,
      "timestamp": "2020-08-21 12:06:37.449432",
      "transactions": []
    },
    {
      "index": 2,
      "previous_hash": "913cc3fe381c77586eef6355c39a8e7d31b257c4870823a7f8bb2784b12eb9b1",
      "proof": 533,
      "timestamp": "2020-08-21 12:59:09.199361",
      "transactions": [
        {
          "amount": "10bcoin",
          "receiver": "Receiver",
          "sender": "Bharathi"
        },
        {
          "amount": 1,
          "receiver": "Bharathi",
          "sender": "56d710bdb1eb447bb4e3a82c3c32bf5d"
        }
      ]
    },
    {
      "index": 3,
      "previous_hash": "063c0a4b20355ec7a63402ebdb5acd9829fa33ac00b4631046b268fad780d3ee",
      "proof": 45293,
      "timestamp": "2020-08-21 13:16:49.391491",
      "transactions": [
        {
          "amount": "15bcoin",
          "receiver": "Naveen",
          "sender": "Bharathi"
        },
        {
          "amount": 1,
          "receiver": "Bharathi",
          "sender": "56d710bdb1eb447bb4e3a82c3c32bf5d"
        }
      ]
    },
    {
      "index": 4,
      "previous_hash": "881ad3ccebbe6f2ffb48e8ed295a1f47aa12c766b5fffab0a85501c23d74976a",
      "proof": 21391,
      "timestamp": "2020-08-21 13:18:49.014229",
      "transactions": [
        {
          "amount": "20bcoin",
          "receiver": "Naveenraja",
          "sender": "Bharathikannan"
        },
        {
          "amount": 1,
          "receiver": "Bharathi",
          "sender": "5b4fb2883b7c4497b5076696cc57d7d9"
        }
      ]
    },
    {
      "index": 5,
      "previous_hash": "a8a887acffbe477c293019b5e33829aa55d848bb726743beb0233e5b518f5b3e",
      "proof": 8018,
      "timestamp": "2020-08-21 13:20:26.953987",
      "transactions": [
        {
          "amount": "25bcoin",
          "receiver": "Naveenraja",
          "sender": "Bharathikannan"
        },
        {
          "amount": 1,
          "receiver": "Bharathi",
          "sender": "68aae997dc6a4c7da90a109586d019d3"
        }
      ]
    }
  ],
  "length": 5
}

Inspired by: https://www.udemy.com/course/build-your-blockchain-az/