Litecoin Cash developer Tanner spoke to CCN about the recent 51% attack on the LCC network and how such attacks could be avoided in future.
Litecoin Cash was created as a way to launch a refined SHA coin to offer SHA256 miners more options and to create the fairest distribution through an IFO (initial fork offering), educating users on safe forking in the process.
Tanner thinks the hashpower used to attack the Litecoin Cash network was rented, with the 51% attack coming only one day after CCN published an article on how this could be achieved on small proof-of-work networks for as little as $500 per hour. CCN interviewed the owner of a website who published their calculations revealing the vulnerability of these networks, including Litecoin Cash.
“The attacker would have had to start with some real LCC, but while they were secretly mining ahead they would have been able to spend that real LCC on the public network, for example transfer it into an exchange.
The secret blocks the attacker was mining and withholding would not have included those spends.
The attacker could then wait for the exchange deposit to confirm, sell the LCC for Bitcoin, and then release their withheld blocks.”
Tanner confirmed that he had seen the website in the above CCN article.
“I have seen that website, and it’s a cold hard wake-up call for any pure proof-of-work coin. It brings home a key point about any proof-of-work coin with a relatively small market cap; at any time you can assume that whichever hashing algorithm is used to secure your blockchain, there is a lot more hashpower available out there for that algorithm than is currently mining your coin.”
Tanner said he couldn’t say whether the specific dollar amounts were accurate, but that the method of renting the hardware to attack networks remotely was definitely feasible.
“This attack was part of a pattern seen across several altcoins within a 2 week period. It’s not clear whether the same attacker or attackers were responsible, but the behaviour was very similar in each case.”
“Most affected coins are starting to announce plans to introduce additional means of securing their networks; in some cases, for example, pure proof-of-work coins are switching to proof-of-work/proof-of-stake hybrid systems.
Most are utilising pre-existing codebases and ideas, though there are few more innovative solutions appearing. ZenCash in particular have released an interesting paper, but I haven’t fully analysed it yet.”
Of course, Litecoin Cash is also working on new security methods designed to prevent such an attack from happening again. Tanner stated that the team also evalutated hybrid PoW/PoS schemes but didn’t find anything already developed by another team that they felt guaranteed their network’s security – so they had to get creative.
As well as securing against 51% attacks, Tanner said they wanted to avoid requiring existing miners or pools to change their behavior — as the original idea was “the SHA256 Litecoin Fork,” the last thing they want is to make things difficult for their mining community.
“We’ve come up with a unique solution, ‘The Hive’, which helps to secure the network against a 51% attacker by ensuring that the public chain has higher work than the attacker can realistically hope to accumulate individually.”
The Hive is an agent-based mining system. Users create “worker bees” which secure the network while earning block rewards for their bee keepers.
“Proof-of-work miners can continue exactly as before, and a further advantage of The Hive is that the network can “see into the future” to a certain extent, with the potential that the network will be able to see upcoming attacks before they happen.”
“We have a preview whitepaper available that fully explains our idea, and we hope to have a testnet up and running within the coming weeks,” he added.
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