Blockchain-Class-Notes

Contains my notes from Blockchain Lectures.

Lecture 1 - 5th August

Blockchain is chain of blocks, each block has set of transactions, based on these transactions it creates a hash code.
These set of blocks have a unique hashcode associated to details of transactions. Combining these blocks make a node.
All cryptos are one possible application of blockchain.
Zero block is called the Genesis Block. (Zero Block: The first block of Blockchain)\

Features of Blockchain

• System of recording information
• Difficult/Impossible to change, hack or cheat
• Fully decentralized p2p data storage spread across all particiapnts that are reffered as nodes.

Features of Distributed Ledger (DLT)

• Programmable i.e Smart Contracts
• Secure
• Anonymous
• Unanimous
• Distributed
• Immutable
• TimeStamped

Lecture 2 - 6th August

Blockchain - Distributed ledger for maintaining a permanent and secure ledger managed by p2p network.\

Blockchain Internals

Miner Node

• Extremely powerful hardware
• Can take multiple transactions, create a hash that meets blockchain's difficulty level
• somebody takes group of transactions and create a valid hash for it.
• Once such block is accepted in blockchain, Miner gets his fees.

Types of Blockchain

Public Blockchain

• Anyone can be a node in a public network and submit transactions
• Example: $BTC, $ETH

Private Blockchain

• use blockchain according to your business logic
• private in scope and limited to defined users.
• Example: Ethereum, Polygon

Permissionless Blockchain

• Anyone can process transactions

Permissioned Blockchain

• Only approved nodes(also referred as users) can process the transaction

Lecture 3 - 12th August

Ethereum

• Blockchain-based computing platform

This includes three things

• Gas: Price per operation
• Nonce: Random number a mining algorithm uses to affect outcome of hashing algorithm
• Difficulty

Accounts in Ethereum

• User accounts
• Contracts

Nodes

• Computers that are part of blockchain network
• Miners are nodes that are willing to participate in transactions and creating a hash for it.

Ether

• Digital currency used by Ethereum
• 10^8 wei = 1 ether

Smart Contracts

• Programmatic definition of business rules for 2 or more entities to transact with each other
• Written and deployed on blockchain framework.

DApps

• Code running on decentralized p2p network.
• DApps = UI + Smart Contracts

Lecture 4 - 13th August

• Create directory called Ethereum - mkdir ethereum

• Create an environment var called ethereum_home export VARIABLE_NAME=Path of folder {export ETHEREUM_HOME=/path} export ETHEREUM_HOME=/Users/abhinav/ethereum

• check environment variables printenv

• Create a file genesis.json in your ethereum_home directory

• To init your first ethereum node:

geth --datadir “$ethereum_home/NUclass” init “<ethereumdir>/genesis.json” [**run once only**]
geth --datadir ”$ethereum_home/NUclass” console 2>console.log
admin. [tab key] to view all options possible with the admin command
admin.nodeInfo - observe the default port and the enode id
personal. [tab key]
personal.newAccount() to create a new account

• Operations

personal.listAccounts() to list accounts
eth. [tab key]
eth.blockNumber should return 0 since we are yet to create our first block\

Create a 2nd node: geth --datadir “$ethereum_home/Nuclass-node2” init “<ethereumdir>/genesis.json” [**run once only**]\

geth --datadir ”$ethereum_home/Nuclass-node2” --port 30304 --nodiscover -- networkid 1234 console 2>console.log [different port number – also, need to restart first node with same networkid]

(On Windows, add --ipcdisable, if you get access denied)