blockchain_python

The github repository contains a basic implementation of a blockchain.

Code implementation contains

Part 1 - Building a Blockchain

By creating Blockchain class that has the main params/data_variables and the main functionality related to the blockchain it's self.

Main params/data_variables of Blockchain class

1. chain list:: which is the list will be updated every time you mine a new block.
2. block:: is the current block which we are trying to mine using the blockchain class functions. Every block has it's own set of key value pair which are 'index', 'timestamp', 'proof', 'previous_hash'.
3. new_proof:: is the value we are trying to find to be able to mine a new block.

Main functionality of Blockchain class

1. fun __init__ is the constructor of the Blockchain class, it initialize the chain list and create the very first block with proof of 1 and previous_hash equals to 0.
2. fun create_block it creates a new block as a new instance of the Blockchain class.
3. fun get_previous_block is for getting the previous block from the chain list and using it's previous_hash for th mining process.
4. fun proof_of_work to proof that the current proof is thr right value using hashlib and sha256 operation for hashing and make sure that the end value starts with '0000'.
5. fun hash using hashlib and sha256 operation for hashing values.
6. fun is_chain_valid to be able to check if the chain values and no fake values.

Part 2 - Mining our Blockchain

Creating a Web App

using Flask.

Creating a Blockchain

creating a new instance from the Blockchain class.

Mining a new block

using that new blockchain use this web based function mine_block to mine a new block.

Getting the full Blockchain

using that new blockchain use this web based function get_chain to get the full chain.

Checking if the Blockchain is valid

using that new blockchain use this web based function is_valid to check is_chain_valid.

Running the app

$ FLASK_APP=blockchain.py flask run
* Running on http://localhost:5000/

Or run our app using the ide to be deployed and start testing it.

Testing

Postman

1. GET http://127.0.0.1:5000/get_chain which will initiate the chain and create the first block.
2. GET http://127.0.0.1:5000/mine_block which will mine a new block.
3. GET http://127.0.0.1:5000/get_chain which will get the new chain after mining that new block form the previous step.
4. Repeat mining step 2 for 5 times for example.
5. GET http://127.0.0.1:5000/get_chain again.
6. GET http://127.0.0.1:5000/is_valid to check if your chain is valid.

Httpie

# Install httpie
$ pip install httpie

$ http http://127.0.0.1:5000/get_chain
$ http http://127.0.0.1:5000/mine_block
$ http http://127.0.0.1:5000/get_chain
# Repeat http http://127.0.0.1:5000/mine_block 5 times.
$ http http://127.0.0.1:5000/get_chain
$ http http://127.0.0.1:5000/is_valid

Curl

$ curl http://127.0.0.1:5000/get_chain
$ curl http://127.0.0.1:5000/mine_block
$ curl http://127.0.0.1:5000/get_chain
# Repeat curl http://127.0.0.1:5000/mine_block 5 times.
$ curl http://127.0.0.1:5000/get_chain
$ curl http://127.0.0.1:5000/is_valid

Dependencies

Flask is the only required dependency.

$ pip install -r requirements.txt