Introduction to Blockchain
• What is
Blockchain?
• History
and Evolution of Blockchain
• Cryptography
Basics
• Blockchain
Networks and Types
Introduction to Blockchain:
Blockchain is a distributed digital ledger technology that
allows transactions to be recorded securely and transparently. It operates on a
decentralized network of computers that work together to verify and record
transactions. The blockchain technology has gained popularity in recent years
due to its ability to eliminate the need for a central authority or
intermediary.
History and Evolution of Blockchain:
The first blockchain was introduced in 2008 as the
underlying technology for Bitcoin, a decentralized digital currency. Since
then, it has evolved into a versatile technology with applications in finance,
supply chain management, healthcare, and many other industries. Today, there
are multiple blockchain platforms and protocols, each with their own unique
features and capabilities.
Cryptography Basics:
Cryptography is a fundamental component of blockchain
technology. It involves using mathematical algorithms to secure data and
communications. In the context of blockchain, cryptography is used to secure
transactions and ensure the integrity of the data stored on the blockchain.
Some common cryptographic techniques used in blockchain include hash functions,
public-key cryptography, and digital signatures.
Blockchain Networks and Types:
The two primary types of blockchain networks are public and
private. Public blockchains are open and accessible to anyone, while private
blockchains are restricted to a specific group of participants. Public
blockchains, such as Bitcoin and Ethereum, are decentralized and rely on
consensus algorithms to validate transactions. Contrarily, private blockchains
are often utilized within organizations and are governed by a single entity.
Here is a simple Python code example that demonstrates how
to create a basic blockchain using hash functions:
python code
import hashlib
class Block:
def __init__(self,
data, previous_hash):
self.data =
data
self.previous_hash = previous_hash
self.hash =
self.generate_hash()
def
generate_hash(self):
data_string =
str(self.data) + str(self.previous_hash)
sha =
hashlib.sha256()
sha.update(data_string.encode('utf-8'))
return
sha.hexdigest()
class Blockchain:
def
__init__(self):
self.chain =
[Block('Genesis Block', None)]
def
add_block(self, data):
previous_hash
= self.chain[-1].hash
new_block =
Block(data, previous_hash)
self.chain.append(new_block)
def
is_valid(self):
for i in
range(1, len(self.chain)):
current_block = self.chain[i]
previous_block = self.chain[i-1]
if current_block.hash !=
current_block.generate_hash():
return
False
if
current_block.previous_hash != previous_block.hash:
return
False
return True
This code creates a Block class that represents a single
block in the blockchain. The Blockchain class contains a list of blocks and
provides methods for adding new blocks and validating the chain. The
generate_hash() method uses the SHA-256 hashing algorithm to create a unique
hash for each block based on its data and the previous block's hash. The
is_valid() method checks that each block's hash matches its data and the
previous block's hash, ensuring the integrity of the blockchain.
