Network Security Concepts in Blockchain

ENPM693 Project

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Project Usage

This project relies on GCP's PubSub offering to work and expects a gcp-pubsub-private-key.json that can be generated in GCP. Provide this path as a variable in constants.py.

This PubSub offering also expects the topics to publish and subscribe to transactions and blocks. These too are specified in the constants.py file

Once these constants are setup, the path of private keys of the transaction's recipients need to be specified in private_keys.py file. These are loaded at runtime.

With all these constants set up, the code is ready to be executed as follows:

1. start miner.py and participant.py in 2 separate terminals
2. edit transactions in transaction_feeder.py and execute it.
3. post execution, use ^C to exit from the miner and participant sessions.

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Block Class

This class represents a block in a blockchain.

Attributes

• index: The index of the block.
• previous_hash: The hash of the previous block.
• proof: The proof of work for the block.
• timestamp: The timestamp of when the block was created.
• transactions: A list of transactions in the block.

Methods

• proof_bytes() -> bytes: Returns the bytes of block data used for calculating the proof of work.
• hash_bytes() -> bytes: Returns the bytes of data used to compute the hash of a block.
• hash() -> str: Returns the SHA256 hash of the block.

Usage

block = Block(index, previous_hash, proof, timestamp, transactions)

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Blockchain Class

This class represents a blockchain.

Attributes

• chain: A list containing blocks in the blockchain.
• proof_length: The length of proof required for adding new blocks to the chain.

Methods

• length() -> int: Returns the number of blocks in the chain.
• first_block() -> Block: Returns the first block in the chain.
• last_block() -> Block: Returns the last block in the chain.
• add_block(block: Block) -> None: Adds a new block to the chain.

Usage

blockchain = Blockchain(proof_length)

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Miner Class

This class represents a miner node in a blockchain network.

Attributes

• blockchain: An instance of the Blockchain class representing the blockchain.
• current_transactions: A list containing current transactions being processed by the miner.
• subscriber: A Google Cloud Pub/Sub subscriber client.
• publisher: A Google Cloud Pub/Sub publisher client.
• topic: A dictionary containing information about topics for adding transactions and blocks.

Methods

• transaction_add_callback(message) -> None: Callback function for adding transactions received through Pub/Sub.
• block_add_callback(message) -> None: Callback function for adding blocks received through Pub/Sub.

Usage

python miner.py

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Participant Class

This class represents a participant node in a blockchain network.

Attributes

• blockchain: An instance of the Blockchain class representing the blockchain.
• subscriber: A Google Cloud Pub/Sub subscriber client.
• publisher: A Google Cloud Pub/Sub publisher client.
• topic: A dictionary containing information about topics for adding blocks.

Methods

• block_add_callback(message) -> None: Callback function for adding blocks received through Pub/Sub.

Usage

python participant.py