Thanks for taking a look at my blockchain project from my recent coursework. This app is from a course I took by David Katz after doing a Python bootcamp. I took this course and have linked the project on my CV to show that I can learn new tech stacks and also to show that if given new opportunities to do so, I will enthusiastically dive in and gain competency with which to serve.

As with many projects that are built in Udemy courses, this app is just a code-along where you build it component by component along with the instructor through the videos in the course. It certainly isn't my engineering design. David Katz is a highly skilled Silicon Valley developer, and there's a big difference in what he and I can create. But with a lot of effort, I did understand everything in the many modules as I built them.

As simplistic as it looks, this app is actually a working blockchain and cryptocurrency with the usual functionalities of:

• Block Mining with Proof of Work
• Difficulty Adjustment
• Transactions
• Transaction Validation
• Block Validation
• Chain Validation

Block Mining with Proof of Work

Here is the mine_block() function inside of the block.py module found in backend/blockchain which performs proof of work and mines a block.

You can see in the call to the crypto_hash() function that the usual data is used to create the hash for the newly mined block, including a timestamp, the previous block's hash, the current difficulty, a nonce, and the data (a transaction pool) to be recorded in the block. The mine_block() function calls the crypto_hash() function until a hash is created which has a count of leading zeroes matching the current difficulty level.

The crypto_hash() function utilizes the Python hashlib module's sha256() function to cryptographically derive a hash from the given inputs as seen here.

More code walkthrough coming soon!

Activate the virtual environment

source blockchain-env/Scripts/activate

Install all packages

pip install -r requirements.txt     

Run the tests

Make sure to activate the virtual environment

python -m pytest backend/tests    

Run the application and API

Make sure to activate the virtual environment

python -m backend.app    

Run a peer instance

Make sure to activate the virtual environment

export PEER=True && python -m backend.app    

Run the frontend

In the frontend directory:

npm run start    

Seed the backend with data

Make sure to activate the virtual environment

export SEED_DATA=True && python -m backend.app