class1.txt

Blockchain:
-----------

Dev:

1. Front end/UI    -  20%
2. Backend         -  70%  (java/node js/go + solidity) ---> 80%
                           (RUST --> PolkaDOT/Solana) ---> 10%
3. Network/admin   -  10%

Prerequiste:

node js --> backend (cohort1)
java    --> smart contracts (cohort 2) -- HYperledger, R3 corda
Linux + docker --> commands
Solidity --> ethereum, polygon


Blockchain network: (B2B) Use cases Banking consortium (5 banks for trade finance bond)

private/enterprise blockchains ----> b2b (insurance bonds, trade bonds, )

public ---> b2c (digtal assets, tokens, nfts, digital currencies)

sbi, icici, hdfc, idfc, pnb -->

(on premises) , (on premises), (on premises), (aws), (gcp)

1. everone in the network should have some visibility on the ledger
2. everyone should have same access to create blocks 

 Consensus ---> mutual agreement among participants

Cryptography --> data encryption, hashing, digital singatures


Class Block
{
  header 
   block id
   timestamp
   nonce
  body
   transaction
}


Hashing --> concept cryptography which enables secure communation

[user1, $100, user2] ---> plain text/raw transaction

hash of the message --> ghg768769867987hb,jhbhj987987987

given input we can calculate output using hashing

 encryption - symmetric/asymetric
 digital signatures
 hashing


Genesis block: first block in blockchain

var genesis = {
  network name: bitcoin
  network id : 756
  no of bitcoins : 1 MN
  start
  end date
} 



hash (genesis) --- hiulhui7869876086098908nkjj98798



genesis block([empty [] + current hash) ---> block 1 (previous hash + current hash) ---> block 2 ----> block3


1500 transactions in the network ---


protocol - 

1. create blocks for every 5 seconds ---> 50
2. crete blocks for 100 transacions ---15
3. create blocks for 400 KB ---> 25





Private blockchains ---> enterprises 5 banks 

public ---> miners/validators ---> to validate the data and append to blocks
            miners create pool of miners(sub groups) ---> control
 400-1000 nodes (network mining is 5-10 large pool of miners) 
 


digital asset ofmy degree:
--------------------------

Name: jag
course: CSE
duration: 4 years
CGPA:8
start date:
end date:

 to smart contracts that creates unique id for me on blockchain for tohers to validate and verify my creditials

tokenizee --- token id (209898098)

query data from blockchain by passing this uniq (209898098), created by university ABC

Fungible tokens vs non fungible tokens:

 Fungible tokens --> each and evry token is same --- digitial currency (bitcoin,ethereum)
 Non fungible token --> each and evry token is diff


Banka, b ,c ,d ,e , bank e (regulator bank) --- USE case

bank a lend 100 CR to bank b (bank a, b) (bank a, b, c, d, e)

bank e wish to verify the amt of bank a lent to other banks ---> it can perform an analytical query on data avaailble in the ledger

public blockchains --> data visiblity of other banks is an issue

privtae blockahins/enterprise blockchains ---> data hiding/private data collection

 based on txn origination , banks can specify the data visilibyt parameters 

 bank a --- bank b , ---- bank e (bank1, transfer amt 100 CR, bank b, approved by bank e)

 c,d----> stores the hash of the data hash(bank1, transfer amt 100 CR, bank b, approved by bank e)


role definitons on transaction level 
--------------------------------------

smart contract:

 if txn == bank A and involved with bank B
   {
     only bank a and bank b  }
 else
  { 
     record/store the transaction
  }


data is stored on blockchains:

1. data can be persisted (backup) on external disk/hardware
2. sync data in the network from others

   seed nodes in the network (this will help in sync up to date ledger)

protocol level ---how many n of seed nodes --- (10-20)

yahoo ---> yahoo

gmail ---> gmail

rediff

hotmail