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Byzantine Generals' Problem Meaning

May 21, 2023 | Updated May 24, 2023
The Byzantine Generals’ Problem is a game theory problem that illustrates how difficult it is for decentralized parties to arrive at a consensus or agree on a single truth without relying on a trusted third party.

What is the Byzantine Generals’ Problem?

The Byzantine Generals’ Problem is a classic game theory problem that has become particularly appropriate for decentralized networks and blockchain.

The problem derives its name from the ancient city Byzantium, which had complex communication and defense systems. The problem is set during an attack on an enemy city, when the generals have to coordinate a joint attack. In the problem, the generals can only communicate with each other through messengers for a course of action. However, some of the messengers or generals may be traitors who might deliver false information, which would lead to a failed attack. The goal is to find a way for the loyal generals to arrive at a consensus despite the possibility of conflicting messages from traitors.

The problem arises because the generals cannot trust their messengers to deliver accurate information. In the context of decentralized systems, the Byzantine Generals’ Problem demonstrates the difficulty in coordinating network users in a trustless environment to come to a common consensus. This is because nodes, which are anonymous and could theoretically be malicious, have to trust each other to arrive at a consensus on a shared ledger.

How does Blockchain Solve the Byzantine Generals’ Problem?

Blockchain technology solves the Byzantine Generals’ Problem through protocols that use fault-tolerant mechanisms like proof-of-work (PoW), proof-of-stake (PoS), and delegated proof-of-stake (DPoS) mechanisms. Blockchains create a layer of trust through a consensus mechanism, where the participating nodes have a copy of the ledger. Every transaction has to be verified by a majority of the nodes for it to be added to the ledger, creating a tamper-proof record of all the information on the network. In addition, blockchains utilize cryptographic methods for encryption to ensure the security of transactions or information within the network.

For example,  Bitcoin addresses the problem by using a blockchain network to hold all transaction history in a public and trustless manner, where all participating nodes have to agree on the transactions that occurred and in the order in which they occurred. Several cryptocurrencies, including Bitcoin, use the proof-of-work mechanism that requires nodes (who represent the generals) to solve a mathematical puzzle in order to add new blocks to the blockchain. The amount of computational work required makes it difficult for a single node to manipulate the blockchain’s history.

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