Blockchain - Explanation
Block
A block is a record that is linked to it's predecessor successor with a unique hash.
Block Chain
A block chain is a collection of these linked blocks. Block chains is required for Non-Fungible Tokens (NFTs) and Cryptocurrencies in their current form.
Qualities of Blockchains
- Immutable
- Persistent
- Distributed
Proof of Work
In order to keep a chronological history of previous blocks in the chain, a nonce is required. A nonce is the number of leading 0 bits when creating a new hash.
The number of leading bit is known as difficulty. Thus the amount of work for generating a new hash exponentially increases per block created. It also makes modifying previous blocks close to impossible as you need to create the following blocks in the chain.
What you will find in this project is an example of simple block chain in Python using an SHA-256 Hash.
How to use
python3 app.py
This will run a flask server on port 5000 that with three end-points:
POST /pay Send JSON data to simulate a purchase
GET /chain Gives the current chain with all it's blocks
POST /mine Takes all the transactions after the last mine and then creates a new block with it