BDCCOIN

[fanifanaseki]

import hashlib
import json
from time import time

class BDCcoinBlockchain:
def init(self):
"""Initialize the blockchain with the genesis block"""
self.chain = []
self.transactions = []
self.create_block(proof=1, previous_hash='0') # Genesis block

def create_block(self, proof, previous_hash):
    """Create a new block and add it to the chain"""
    block = {
        'index': len(self.chain) + 1,
        'timestamp': time(),
        'transactions': self.transactions,
        'proof': proof,
        'previous_hash': previous_hash
    }
    self.transactions = []
    self.chain.append(block)
    return block

def get_last_block(self):
    """Return the last block in the chain"""
    return self.chain[-1]

def add_transaction(self, sender, receiver, amount):
    """Add a new transaction to the list"""
    self.transactions.append({
        'sender': sender,
        'receiver': receiver,
        'amount': amount,
        'coin': 'BDCcoin'
    })
    return self.get_last_block()['index'] + 1

def proof_of_work(self, previous_proof):
    """
    Proof of Work Algorithm:
    - Find a number 'new_proof' such that hash(new_proof^2 - previous_proof^2) starts with 4 zeros
    """
    new_proof = 1
    while True:
        hash_val = hashlib.sha256(str(new_proof**2 - previous_proof**2).encode()).hexdigest()
        if hash_val[:4] == '0000':
            return new_proof
        new_proof += 1

def hash(self, block):
    """Create SHA-256 hash of a block"""
    encoded_block = json.dumps(block, sort_keys=True).encode()
    return hashlib.sha256(encoded_block).hexdigest()

def is_chain_valid(self, chain):
    """Verify if the given blockchain is valid"""
    previous_block = chain[0]
    for index in range(1, len(chain)):
        block = chain[index]
        if block['previous_hash'] != self.hash(previous_block):
            return False

        previous_proof = previous_block['proof']
        proof = block['proof']
        hash_val = hashlib.sha256(str(proof**2 - previous_proof**2).encode()).hexdigest()
        if hash_val[:4] != '0000':
            return False

        previous_block = block

    return True

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✅ ব্যবহার (Demo Example)

================================

if name == "main":
blockchain = BDCcoinBlockchain()

# একটি লেনদেন যুক্ত করা
blockchain.add_transaction(sender='Alice', receiver='Bob', amount=100)

# ব্লক মাইন করা
previous_block = blockchain.get_last_block()
previous_proof = previous_block['proof']
proof = blockchain.proof_of_work(previous_proof)
previous_hash = blockchain.hash(previous_block)
block = blockchain.create_block(proof, previous_hash)

print("✅ Block mined successfully:")
print(json.dumps(block, indent=4))

[fanifanaseki]

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