This post will talk about what is blockchain technology, it’s types, and a simple example on how to create a blockchains using python so, let’s get started!
Blockchain Technology
Blockchain technology is a decentralized digital ledger that allows for secure, transparent, and tamper-resistant record-keeping. It allows multiple parties to participate in a network without the need for a central authority to validate transactions, making it a trustless system.
In a blockchain, each block contains a cryptographic hash of the previous block, creating a chain of blocks that are linked together. This ensures the integrity of the data stored in the blockchain, as any attempt to alter a previous block would require the alteration of all subsequent blocks as well, which is computationally infeasible.
Types of blockchains
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- Public blockchains: These are open to anyone to participate and are permissionless, meaning that anyone can read, write, and participate in the network without the need for permission. Bitcoin and Ethereum are examples of public blockchains.
- Private blockchains: These are permissioned, meaning that access to the network is restricted to a specific group of participants. Private blockchains are often used by organizations for internal purposes, such as supply chain management.
- Hybrid blockchains: These combine elements of both public and private blockchains. For example, a consortium blockchain may be a private blockchain that allows a specific group of participants to participate in the network, but it is still decentralized and open to the public to some extent.
How does blockchain work?
At its core, a blockchain is a decentralized digital ledger that allows for secure, transparent, and tamper-resistant record-keeping. Here’s how it works:
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- Transactions are verified: When a transaction is initiated, it is broadcast to the network of nodes (or computers) that make up the blockchain. These nodes verify the transaction and its authenticity, ensuring that it follows the rules and protocols of the blockchain.
- Transactions are grouped into blocks: Once a certain number of transactions are verified, they are grouped into a block. Each block contains a cryptographic hash of the previous block, creating a chain of blocks that are linked together. This ensures the integrity of the data stored in the blockchain, as any attempt to alter a previous block would require the alteration of all subsequent blocks as well, which is computationally infeasible.
- Blocks are added to the chain: The newly created block is added to the existing chain of blocks, which is distributed across the network of nodes. This makes the blockchain decentralized, as there is no single central authority controlling the network.
- Consensus is reached: In order for a block to be added to the chain, a consensus mechanism is used to ensure that all nodes on the network agree that the block is valid. Depending on the type of blockchain, this may involve a proof-of-work, proof-of-stake, or other consensus algorithm.
- The blockchain is updated: Once a block is added to the chain, the information it contains becomes a permanent part of the blockchain. This creates a transparent and immutable ledger that can be used for a variety of purposes, such as tracking financial transactions, managing supply chains, or securing data.
Example of Blockchain
Now let’s see a simple example of a blockchain, implemented in Python
Step 1: The below code defines a simple blockchain with the ability to add new blocks and transactions, calculate a hash for each block, and use a proof-of-work algorithm to mine new blocks.
import hashlib
import json
from time import time
class Blockchain:
def __init__(self):
self.chain = []
self.current_transactions = []
self.create_block(proof=1, previous_hash=’0′)
def create_block(self, proof, previous_hash):
block = {
‘index’: len(self.chain) + 1,
‘timestamp’: time(),
‘transactions’: self.current_transactions,
‘proof’: proof,
‘previous_hash’: previous_hash or self.hash(self.chain[-1]),
}
self.current_transactions = []
self.chain.append(block)
return block
def new_transaction(self, sender, recipient, amount):
self.current_transactions.append({
‘sender’: sender,
‘recipient’: recipient,
‘amount’: amount,
})
return self.last_block[‘index’] + 1
@staticmethod
def hash(block):
block_string = json.dumps(block, sort_keys=True).encode()
return hashlib.sha256(block_string).hexdigest()
@property
def last_block(self):
return self.chain[-1]
def proof_of_work(self, last_proof):
proof = 0
while self.valid_proof(last_proof, proof) is False:
proof += 1
return proof
@staticmethod
def valid_proof(last_proof, proof):
guess = f'{last_proof}{proof}’.encode()
guess_hash = hashlib.sha256(guess).hexdigest()
return guess_hash[:4] == “0000”
Step 2: Here’s an example of how to use this blockchain to create a new block and transaction:
blockchain = Blockchain()
# Create a new transaction
blockchain.new_transaction(‘Alice’, ‘Bob’, 10)
# Mine a new block
last_block = blockchain.last_block
last_proof = last_block[‘proof’]
proof = blockchain.proof_of_work(last_proof)
previous_hash = blockchain.hash(last_block)
block = blockchain.create_block(proof, previous_hash)
print(blockchain.chain)
Step 3: This code creates a new instance of the Blockchain class, adds a new transaction from Alice to Bob, mines a new block, and prints out the current state of the blockchain. The output should look something like this:
[{‘index’: 1, ‘timestamp’: 1639568479.583073, ‘transactions’: [], ‘proof’: 1, ‘previous_hash’: ‘0’}, {‘index’: 2, ‘timestamp’: 1639568527.591487, ‘transactions’: [{‘sender’: ‘Alice’, ‘recipient’: ‘Bob’, ‘amount’: 10}], ‘proof’: 35293, ‘previous_hash’: ‘c789e5e5c1d5fb5f3b3aa16984f9a30e7a1b276d2f7c2471e2f2e755d928007’}]
This is just a very simple example, but it should give you an idea of how a blockchain works and how you can implement one in code.
That’s all for this post! Hope you enjoyed reading it.
You can also check some interesting posts on machine learning from blog page: https://ai-researchstudies.com/blog/
You can explore a bit more on blockchain and AI here: https://www.ibm.com/topics/blockchain-ai
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