Ethereum: Does Bitcoin Blockchain Solve Byzantine General Problem?
The Byzantine General Problem (BGP) is a complex computational puzzle that was first proposed by Dimitris J. Christodoulou and Silvio Micali in 1980. It’s a challenging problem for the Byzantine Network (BNets), which refers to the collective behavior of nodes on the blockchain network, including Ethereum. The BGP states: given multiple nodes on a graph, determine if it is possible for at most two nodes to agree on any given value.
Bitcoin Blockchain and Byzantine General Problem
While Bitcoin’s blockchain solves some problems related to Byzantine Generals, such as the difficulty of solving a linear congruence equation (a form of the BGP), Ethereum’s mainnet blockchain does not directly solve the problem. However, it provides an alternative approach that can be used in conjunction with other solutions.
Bitcoin Blockchain Solution
A Bitcoin block is essentially a group of transactions bundled together and verified by a network of computers called miners. These nodes work together to validate the transactions and create a new block. One way to view this process as solving the BGP is through the concept of “consensus”.
In the context of blockchain, consensus refers to the agreement among nodes on the collective state of the network. For instance, when multiple nodes on a graph agree on a value (e.g., a timestamp), it means that all nodes have reached a common understanding. This consensus process is not directly related to solving the BGP, but rather serves as a mechanism for ensuring that nodes maintain a shared view of the blockchain state.
Ethereum’s Approach
Ethereum, built on top of a proof-of-work (PoW) consensus algorithm, provides an alternative approach to solving the BGP. One way to solve the problem is through the use of “decentralized orderings”, which involve aggregating multiple data sources to produce a single, authoritative order.
In Ethereum, nodes can participate in the network and contribute their local ordering information (e.g., transaction timestamps) to achieve a shared view of the blockchain state. This allows nodes to agree on the collective state of the network without relying solely on central authorities or consensus mechanisms like Bitcoin’s.
Example: Ethereum’s Byzantine General Problem Solution
To illustrate how Ethereum solves the BGP, consider the following scenario:
Imagine two nodes, Node A and Node B, connected in a graph. Each node has its own set of local ordering information (e.g., transaction timestamps) for a particular block of transactions. The goal is to determine if it’s possible for at most two nodes to agree on the collective state of the network.
Node A knows that all transactions in this block have been verified by Node B and are therefore “valid”. However, Node B may not know anything about other blocks or transactions outside its local ordering information. In this case, Node A can use Ethereum’s decentralized orderings to aggregate multiple data sources (e.g., node timestamps) and produce a single, authoritative order.
By doing so, Node A can determine if at most two nodes agree on the collective state of the network, thus solving the Byzantine General Problem for that particular block. This approach provides an alternative solution to the BGP problem that is more resilient against Byzantine attacks.
Conclusion
In conclusion, while Bitcoin’s blockchain solves some problems related to the Byzantine General Problem, Ethereum’s mainnet blockchain does not directly solve the problem. However, Ethereum’s decentralized orderings approach can be used in conjunction with other solutions to provide an alternative method for solving the BGP problem.