Dash has announced the future implementation of ChainLocks, an approach to solving a variety of network disruptions, including 51% attacks.
In a recent blog post, Dash developer Codablock explains a new approach to security in an upcoming release. The new Dash Improvement Proposal (DIP) 8, dubbed ChainLocks, will leverage long-living masternode quorums (LLMQs) to sign blocks as they are seen by the network, protecting against attacks and attempts to reverse transactions:
“The idea of ChainLocks is to perform a verifiable network-wide measurement/vote of the “first-seen” rule. For each block, an LLMQ of a few hundred masternodes is selected and each participating member signs the first block that it sees extending the active chain at the current height. If enough members (e.g. >= 60%) see the same block as the first block, they will be able to create a P2P message (CLSIG) and propagate it to all nodes in the network. There are some more details to this process, especially when multiple miners find a block at approximately the same time.”
The most important benefit of this new approach is that it makes purely mining-based network attacks impossible, meaning that 51% attacks, such as what recently threatened the Bitcoin Cash network, will no longer be a threat on their own. Additionally, challenges related to mining another chain in secret such as selfish mining and chain reorganizations will similarly become a concern of the past:
“It removes all incentives for miners to cause chain reorganizations. Many attacks based on secret or selfish mining become impossible as they all depend on miners withholding longer and secret chains. Under the current consensus rules, such chains would override the publicly known chain and cause a chain reorganization when published. With ChainLocks however, miners are incentivized to publish every block immediately, even if they in theory have enough hash power to overrule every other miner. Failure to publish creates substantial risks for a malicious miner since any secret chain (even if thousands of blocks longer) would be immediately invalidated if another honest miner publishes a valid block that receives a CLSIG before the secret chain is revealed.”
On the consumer side, the introduction of chain locks means that transactions can be trusted as secure after a single confirmation:
“The most important effect for normal users and merchants is that transactions can be considered fully confirmed after the first on-chain confirmation inside a block protected by ChainLocks. Transactions can no longer vanish from the chain since reorganization of signed/locked blocks is not possible.”
At present, most services such as exchanges require 1-3 confirmations for Bitcoin transactions to be trusted, with 5-6 for Dash. With the implementation of ChainLocks, this would no longer be necessary. Further details into the specifics of ChainLocks can be found in the DIP 8 specifications.
ChainLocks not possible on most cryptocurrencies
Features such as ChainLocks are made possible because of the Dash masternode network, and are not able to be implemented in the majority of cryptocurrencies. This is due to the fact that nodes on most chains are vulnerable to Sybil attacks, with a potential attacker able to spin up thousands of nodes with relative ease:
“One of the main prerequisites required to make ChainLocks secure is a Sybil protected network of semi-trusted nodes. A coin that does not offer such a class of nodes will not be able to implement something like ChainLocks in a secure manner. In Bitcoin for example, anything that would rely on “votes” of individual nodes can be gamed by simply starting up thousands of malicious nodes.”
Dash is able to avoid this risk by using masternodes, which require nodes to prove ownership of 1,000 Dash, preventing an attacker from running a majority of nodes without owning a significant portion of the entire coin supply:
“In Dash, the Masternode network is protected against Sybil attacks by requiring a collateral of 1000 Dash per Masternode. This makes it economically impractical to perform a Sybil attack, simply because buying enough Masternodes would require substantial financial resources, which would be put at high risk while performing any attacks. With the current parameters that we target for LLMQs, an attacker would have to buy at least 60% of all Masternodes to get a realistic chance of success.”
Dash’s masternode network enables a number of extra features and improvements, including instant transactions, advanced privacy, and governance, with ChainLocks only the latest in a long list of improvements only possible because of the masternode innovation.
Overhaul to increase security and efficiency for the same cost, half the energy consumption
In addition to increased security and reduced risk of network disruptions and malicious behavior by miners, ChainLocks also enable Dash’s security model to operate at vastly increased efficiency over other proof-of-work setups. As commenter 1bet 1beer pointed out, Dash’s block reward split allows its security model to operate on significantly reduced hashrate, and therefore energy consumption, compared to other networks:
“Personally one thing I was worried about is the fact that mining rewards will be lowered over time, due to the fact of lower block rewards and at the same time the aim is to keep transaction costs as low as possible as well, this would result in much lower hashrates, which in turn would make it that much more likely that some could attempt attacks as you have described. But now that is not longer possible, much lower mining rewards doesn’t mean higher risks, and the same time it will substantially decrease energy costs as well ! In other words there will be no need to keep transaction cost artificially high to protect against attacks. POW just got a how lot greener from my point of view.”
Additionally, because of the block reward split, Dash’s allocation of provides significantly more network security for the same total reward than a simple 100% mining reward. This means that, compared to an equally-valued network using basic proof-of-work alone, Dash can provide far superior security for the same price and half the approximate energy consumption.