Node.js Blockchain Simulation Guide & Implementation

Node.js Blockchain Architecture

Assignment Solution: Custom Data Structures, Cyclic Mining, and Economic Simulation

Network Topology & Wallets

The simulation initializes a closed network of 10 participants. Wallets A, B, C, D, and E are designated as Miners responsible for block creation. Wallets F, G, H, I, and J act as standard Users. Every participant begins with an initial balance of 100 coins to facilitate immediate transaction testing.

Transaction Fee Economics

An aggressive deflationary mechanism is implemented where base fees are burned. Miners are incentivized via a priority fee and a significant block reward. This chart breaks down the coin distribution for a single mined block header.

Data Integrity: Merkle Tree

A custom Merkle Tree class was implemented to ensure transaction integrity. By recursively hashing transaction pairs, we generate a single 'Root Hash'. This root is stored in the block header, allowing lightweight verification of any transaction in the block without downloading the entire ledger.

Efficiency: Bloom Filter

To optimize search speed, a Bloom Filter class is integrated. This space-efficient probabilistic data structure allows us to rapidly query if a transaction exists within a block. While false positives are mathematically possible, false negatives are impossible, making it ideal for lighter client queries.

Consensus: Round-Robin Mining

Deterministic Consensus: Mining privileges rotate among Minters A-E in a fixed cyclic order.

Order Flow: The sequence A → B → C → D → E → A repeats continuously.

Load Balancing: This ensures fair distribution of the 60 coin block reward across all mining nodes.

Block Structure & Limits

Each block is strictly capped at 50 transactions. This includes standard user transfers and the mandatory final 'Coinbase' transaction. This final transaction aggregates the 60 coin global reward plus all 'Priority Fees' collected from the other 49 transactions, crediting them to the current round's miner.

Simulation Parameters

The simulation processes mock traffic to stress-test the network. 200 random transactions are generated between the 10 wallets. The system runs the mining loop until the mempool is fully drained into blocks.

Implementation Details & Notes

Core: Single-file Node.js solution (`main.js`) containing Wallet, Transaction, Block, and Blockchain classes.

Structures: Manual implementation of `MerkleTree` (SHA256 based) and `BloomFilter` (MurmurHash approximation).

Verification checks: Includes a final routine that attempts to validate a tampered transaction against the Merkle Root, proving integrity measures work.

Known Limitations: The simulation runs synchronously. In a real-world scenario, mining would be an async operation with network propagation delays.

How to Run the Code

1. Ensure Node.js is installed on your machine. 2. Place `main.js` in your directory. 3. Open terminal and run: `node main.js`. 4. Observe the console output for block mining logs. 5. View the final summary report titled '--- Final Financial Report ---'.