Simple Blockchain Demo With Python

Blockchain, is a growing list of records, called blocks, which are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (generally represented as a merkle tree root hash). In this post we will no discuss about fundamentals of Blockchain as it was discussed in previous blog. Also there is a nice Visualization of Blockchain by Anders Brownworth at Github.

Basically we will just implement Block, Basic Blockchain Architecture, and very simple Blockchain Network.

import hashlib


class Block:
    # Defining Block Structure
    def __init__ (self, no, nonce, data, hashcode, prev):
        self.no = no
        self.nonce = nonce
        self.data = data
        self.hashcode = hashcode
        self.prev = prev

    def getStringVal (self):
        return self.no, self.nonce, self.data, self.hashcode, self.prev
    

class BlockChain:
    # Defining simple Blockchain structure, adding blocks and chaining them together
    def __init__(self):
        self.chain = []
        self.prefix = "0000"
    
    def addNewBlock (self, data):
        no, nonce,  prev  = len(self.chain), 0 ,  "0" if len(self.chain)==0 else self.chain[-1].hashcode
        myHash = hashlib.sha256(str(data).encode('utf-8')).hexdigest()
        block = Block (no,nonce,data,myHash,prev)
        self.chain.append (block)
    
    def printBlockChain(self) :
        chaintDict = {}
        for no in range (len(self.chain)) :
            chaintDict[no] = self.chain[no].getStringVal()
        print…