Abstract / Introduction

The Proof-of-Work (PoW) consensus mechanism, fundamental to blockchains like Bitcoin, is vulnerable to a "51% attack" where a malicious miner with majority computational power can manipulate the blockchain.

This project implements a proactive defense algorithm named "Safe Mode Detection" to counter this threat. The core idea is to modify the consensus rules to impose a hard limit on consecutive blocks a single miner can produce and to implement a Unspent Transaction Output (UTXO) based comparison mechanism to detect fraudulent chains attempting double-spending utilizing a 51% attack.

Functional Requirements:

• Implement a blockchain to configure a malicious miner capable of initiating a 51% attack by building a private chain.
• Implement the "Long Private Chain (LPC)" defense: The system must automatically reject any new block that would create a sequence of six or more consecutive blocks from the same miner on the honest chain.
• Develop a comprehensive simulation framework to run multiple scenarios: an attack under standard consensus rules, and an attack under the modified consensus rules.
• Generate and present results analyzing the success rate of attacks, the structure of the final blockchain, and the computational performance of the proposed defense.