Chapter03

Chapter 3, Cryptography in Blockchain

This chapter explains how blockchain technology makes use of few of the cryptographic primitives such as hash functions and digital signatures.

quick start

Blockchain example

Using package

Find the python package which has the all the functions bundled together.

pip install justblockchain

    >>> from justblockchain import justblockchain
    
    >>> blockchain = justblockchain.Blockchain()
    
    >>> blockchain.add_block("some block content")

    #display the blockchain
    >>> blockchain.chain
    [{'previous_hash': '0', 'hash':
    '816534932c2b7154836da6afc367695e6337db8a921823784c14378abed4f7d7',
    'timestamp': 1465154705, 'index': 0, 'data': 'my genesis block!!'},
    {'previous_hash':
    '816534932c2b7154836da6afc367695e6337db8a921823784c14378abed4f7d7', 'hash':
    'a046e0b31d2374d171a6bf62f15261f8bb1f71e6351aab2ce7ce6d550506d9ee',
    'timestamp': '1521013680', 'index': 1, 'data': 'some block content'}]

Using script

NOTE: Make sure that you are using python 3

• Install the requirements

  pip install -r requirements.txt

• Execute the application

  python blockchain_example.py

Hash nonce example

python hash_nonce_example.py

Proof-of-work example

python proof_of_work_example.py

Digital signature example

python digital_signature_example.py