Ethereum: How hard is it to alter a block after it was found?

The Complexity of Editing Blocks on the Ethereum Network

Ethereum, one of the most widely used blockchain platforms, relies heavily on the decentralized mining process. Miners compete to solve complex mathematical puzzles in order to validate transactions and create new blocks. However, editing a block after it has been created is not as simple as it may seem.

In this article, we will delve into the intricacies of the Ethereum block editing process and whether miners can easily edit a block or whether there are any limitations to doing so.

The Mining Process

When a miner discovers a valid block on the Ethereum network, they typically submit it to the blockchain as a proposed change. The proposed change is then reviewed by the Ethereum community through a consensus mechanism called Proof of Work (PoW). Miners who believe their solution is better than the original solution are incentivized to solve the puzzle and add their solution to the block.

The Modified Block

Once a miner has added their solution, they must verify that it is correct. They do this by solving another puzzle, known as the “target hash,” which must be less than or equal to 6,000 times the target hash of the previous block. If the solution is valid, the modified block is included in the next block.

Can miners modify a block?

Now, let’s address the question at hand: can miners modify a block after it has been created? The answer is yes, but with some caveats.

In Ethereum, each block contains multiple transactions that are grouped together and verified using PoW. When a miner finds a valid block, they don’t simply add new transactions to the existing block. Instead, they create a new block with the modified transactions inserted into it.

Modified Block Structure

Miners can modify blocks in a number of ways:

• Inserting New Transactions: Miners can insert new transactions into an existing block by creating a new block and inserting the modified transaction into it.

• Removing transactions: Miners can also remove transactions from an existing block by solving another puzzle, which allows them to delete a specific transaction without affecting the entire block.

How ​​do miners know if they can modify a block?

To determine whether a miner can modify a block or not, they must solve the target hash for the proposed modification. However, this process has limitations:

• Miner knowledge: The miner must have complete knowledge of the Ethereum network and all previous blocks to ensure that their solution is valid.

• Time constraints: Miners only have a limited amount of time (known as the “slush period”) before the block is merged with other blocks in the network.

What happens if a miner manages to modify a block?

If a miner successfully modifies a block, they will be rewarded with a certain number of Ethereum tokens known as “gas.” The gas limit is determined by the Ethereum Virtual Machine (EVM) and is calculated based on the complexity of the puzzle that needs to be solved.

Conclusion

In conclusion, modifying a block after it has been created in Ethereum is not as simple as it may seem. Miners can modify blocks, but they must have complete knowledge of the network and solve the target hash for the proposed modification. The process involves creating a new block with modified transactions inserted into it, which requires significant computing power.

Although it is possible to modify a block, miners are typically limited by their knowledge and time constraints. It is worth noting that the Ethereum development team has implemented measures to prevent malicious modifications, such as the use of sharding and zero-knowledge proofs.

In summary, the complexity of modifying blocks on the Ethereum network makes it difficult for miners to modify a block after it has been created.