https://github.com/vndee/blockchain-demo

A very simple implementation of blockchain and its applications in Python.
https://github.com/vndee/blockchain-demo

blockchain

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A very simple implementation of blockchain and its applications in Python.

• Host: GitHub
• URL: https://github.com/vndee/blockchain-demo
• Owner: vndee
• License: mit
• Created: 2023-01-29T06:26:33.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2023-02-22T15:53:41.000Z (over 2 years ago)
• Last Synced: 2025-01-19T07:26:50.113Z (9 months ago)
• Topics: blockchain
• Language: HTML
• Homepage:
• Size: 616 KB
• Stars: 3
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
A very simple implementation of blockchain and its applications in Python.

- [Blockchain](#blockchain)

- [Cryptocurrency](#cryptocurrency)

- [Smart Contracts](#smart-contracts)

### Blockchain

To use the base functionality of the blockchain, you can use the `Blockchain` class. It has the following methods:

- `new_block`: Adds a block to the blockchain.

- `hash`: Hashes a block.

- `proof_of_work`: Simple Proof of Work Algorithm:

    - Find a number p' such that hash(pp') contains leading 4 zeroes, where p is the previous p', p is the previous nonce, and p' is the new nonce.

    - The number of leading zeroes can be changed by changing the `difficulty` variable.

    - The `proof_of_work` method returns the nonce that satisfies the above condition.

    - The `new_block` method calls the `proof_of_work` method to get the correct nonce for the new block.

- `check_valid_nonce`: Checks if the nonce satisfies the proof of work condition.

- `check_valid_chain`: Determines if a given blockchain is valid.

I also add a REST API server to serving these above functions. The API has the following endpoints:

- `/mine-block`: Mines a new block.

- `/get-chain`: Returns the full blockchain.

- `/is-valid`: Checks if the blockchain is valid.

In order to try out the demo, you can run the following commands:

```bash

# Install FastAPI and uvicorn

$ pip install fastapi uvicorn

# Run the server

$ uvicorn blockchain:app

```

Now, navigate to `http://localhost:8000/` to have a look at the demo page and `http://localhost:8000/docs` for the detail

documentations. The app behaviors should be like the following:

Figure 1: Mine a block

![Mine a block](assets/mine.png)

Figure 2: Get the blockchain

![Get the blockchain](assets/get-chain.png)

Figure 3: Check if the blockchain is valid

![Check if the blockchain is valid](assets/check-valid.png)

Developed by [Duy Huynh](https://duy-huynh.com/), 2023.