Casa founder Jameson Loop has published a new post in which he talks about the possibility of a so-called “slow block validation attack.” According to him, this is a serious threat to the integrity of Bitcoin (BTC). A slow block validation attack can be effective for a malicious miner.
The attack involves creating blocks that are too difficult to validate. This forces other miners to spend more resources and time verifying them. This creates a time lag, allowing the attacker to gain an advantage over the rest of the network. Developers have long warned about such threats, and it is one of the reasons why they insist on small block sizes.
One of the most well-known threats was the attack on quadratic signature hashing, which was fixed with the introduction of Segregated Witness (SegWit). However, there are still unresolved issues, such as the excessive computational costs of transaction validation. The Great Script Restoration project, led by Rusty Russell, aims to address these issues in order to optimize the computations used to verify transactions.
"The study showed that the attack on slow block validation is not as destructive as previously thought. For example, if a miner with 1% of the total hashrate gets a 7-minute advantage at the start of mining the next block, its effectiveness doubles. A miner with 5% of the hashrate will need an 8-minute advantage, and a miner with 10% will need a 9-minute advantage. As the attacker's hashrate increases, the attack becomes less effective," Loop noted.
According to the expert, if difficult-to-validate blocks start appearing in the network en masse, this will not lead to an immediate catastrophe. Most likely, professional miners, faced with such an attack, will not stop mining coins, but will simply validate only the block headers, leaving the body with transactions for later.
However, even if the attacker does not become the dominant miner, he can become the only participant including transactions in blocks, which will significantly reduce the network throughput. In the case of high demand for the blockchain, the space for transactions will decrease sharply, which will lead to a sharp increase in fees.
