Toward a 12-second Block Time

The blockchain, a decentralized platform that enables secure and transparent transactions, has been plagued by a significant issue: the sheer length of delay before a transaction gets finalized. In the Bitcoin network, for instance, one confirmation takes an average of 10 minutes, but in reality, it takes much longer due to statistical effects. This delay is not only inconvenient but also poses a significant threat to the security and stability of the network.

Stale Rates and Centralization

The problem arises when we take into account the fact that network propagation is not instant. According to a 2013 paper from Decker and Wattenhofer in Zurich, once a miner produces a block on average it takes 6.5 seconds for the block to reach 50% of nodes, 40 seconds for it to reach 95% of nodes, and the mean delay is 12.6 seconds. This gives rise to the following problem: if, at time T = 500, miner M mines a block B' on top of B (where "on top of" is understood to mean "pointing to as the previous block in the chain"), then miner N might not hear about the block until time T = 510, so until T = 510 miner N will still be mining on B. If miner B finds a block in that interval, then the rest of the network will reject miner B's block because they already saw miner M's block which has an equal score.

The Impact of Stale Rates on Centralization

The stale rate has a significant impact on centralization. The more time it takes for blocks to propagate, the more likely it is that a single miner or a small group of miners will dominate the network. This is because the miner who produces the block first has a significant advantage over other miners, as they are more likely to have their block accepted by the network. As a result, the network becomes more centralized, and the security and stability of the network are compromised.

GHOST: A Solution to the Problem

The GHOST (Graphical History Object) protocol, proposed by Aviv Zohar and Yonatan Sompolinsky in 2013, is a solution to the problem of stale rates and centralization. The protocol takes stale blocks into account even if they are not part of the main chain, and rewards them with a smaller amount of cryptocurrency. This approach has several benefits, including:

Reduced stale rates: By taking stale blocks into account, the protocol reduces the number of stale blocks that are produced, which in turn reduces the stale rate.
Increased security: By rewarding stale blocks, the protocol incentivizes miners to produce blocks that are more likely to be accepted by the network, which increases the security of the network.
Reduced centralization: By rewarding stale blocks, the protocol reduces the advantage that a single miner or a small group of miners has over other miners, which reduces centralization.

Single-Level GHOST

Single-level GHOST is a simplified version of the GHOST protocol that only takes into account blocks that are one level back in the chain. This approach has several benefits, including:

Reduced complexity: Single-level GHOST is simpler to implement than the full GHOST protocol, which makes it easier to deploy and maintain.
Increased efficiency: Single-level GHOST is more efficient than the full GHOST protocol, which reduces the computational resources required to implement the protocol.
Reduced centralization: Single-level GHOST reduces the advantage that a single miner or a small group of miners has over other miners, which reduces centralization.

Four-Level GHOST

Four-level GHOST is a more advanced version of the GHOST protocol that takes into account blocks that are up to four levels back in the chain. This approach has several benefits, including:

Reduced stale rates: Four-level GHOST reduces the stale rate by taking into account blocks that are up to four levels back in the chain.
Increased security: Four-level GHOST increases the security of the network by incentivizing miners to produce blocks that are more likely to be accepted by the network.
Reduced centralization: Four-level GHOST reduces the advantage that a single miner or a small group of miners has over other miners, which reduces centralization.

Twelve-Second Block Time

The twelve-second block time is a significant improvement over the current block time of ten minutes. This improvement has several benefits, including:

Reduced stale rates: The twelve-second block time reduces the stale rate by allowing blocks to propagate more quickly.
Increased security: The twelve-second block time increases the security of the network by incentivizing miners to produce blocks that are more likely to be accepted by the network.
Reduced centralization: The twelve-second block time reduces the advantage that a single miner or a small group of miners has over other miners, which reduces centralization.

In conclusion, the twelve-second block time is a significant improvement over the current block time of ten minutes. This improvement has several benefits, including reduced stale rates, increased security, and reduced centralization. The GHOST protocol, including single-level and four-level GHOST, is a solution to the problem of stale rates and centralization. By taking stale blocks into account and rewarding them with a smaller amount of cryptocurrency, the protocol reduces the stale rate, increases security, and reduces centralization.

Source: https://blog.ethereum.org/en/2014/07/11/toward-a-12-second-block-time