What concerns you about blockchain tech is the memory problem of the blockchain itself. Is it possible to shut down a blockchain (Bitcoin’s system) for an hour, delete all of the blocks except the genesis block, and restart the blockchain again? This would result in a one-hour shorter chain than the current longest chain, but since it’s the longest chain, it would be accepted as valid by the network. In this article, we’ll explore the idea of a 51% attack on the blockchain and how it could be used to delete blocks from the chain maliciously. We’ll also discuss some potential solutions to this problem.
What is a 51% Attack?
A 51% attack is a double-spend attack that occurs when a single entity controls more than 50% of the network hash rate. This allows them to create two versions of the blockchain, one of which they can control and manipulate. In a 51% attack, an attacker can:
- Prevent new transactions from being confirmed
- Reverse transactions that have already been confirmed
- Double-spend coins