Why The Web3?
- The Web3 Revolution
- Cryptography
- How the Blockchain uses Cryptography
Network Attacks
All entries on the blockchain are read-only. Once a block of transactions is accepted by the network, it cannot be easily changed or removed. All blocks would have to be recomputed for that to happen, which would require the majority of the network participants to agree over such changes. An attacker would need to redo the computational work of all successor blocks, on the majority of the network nodes(Computers). This would require control over, or bribing of, the majority of the network nodes. Even if it would be possible to perform these computations within the block-creation period, the cost would be much higher than the rewards for attacking the network. While manipulation is possible, the mechanism is designed to make it infeasible.
Thought Experiment
51% Attack:
A Proof-of-Work network, like Bitcoin, stays safe as long as most of the miners (computers doing the work) are honest. A "51% attack" happens if one person or group controls more than half of the computing power. They could then manipulate the network and change the records. In Bitcoin's 15 years, no one has been able to successfully take control and manipulate the network.
A successful 51 percent attack could have the following impact: It would allow you to
- change network rules
- change blocks by adding or removing transactions, which requires additional Proof-of-Work (the older a transaction is, the harder an attack gets)
- Censor participants and therefore transactions of these participants
- send transactions and then reverse them
What a 51 percent attack cannot do is
- change existing transactions or fake transactions, like: ( changing the amount sent in an existing transaction)
- sending someone's tokens without their approval
This is because all transactions need to be signed with the private key of the token owner, which cannot be revealed by majority agreement of the network. Changing a detail in an existing transaction would render the ledger "Illegitimate," as a transaction without a valid signature would be in it.
