The Bitcoin Satoshi Vision (BitcoinSV) blockchain has suffered a series of block re-oganizations, putting the integrity of its network in question.

On 18th April 2019, our Bitcoin Cash SV [sic] node experienced twoblock re-organizations. First, a three block re-organization, followed by a six block re-organization,tweetedBitMEX Research, the analysis arm of digital asset exchange BitMEX.

Block re-organizations occur when cryptocurrency miners are forced to orphan blocks after theyve been mined.This can happen when the network is too slow to propagate blocks effectively, and bigger blocks (like the ones featured by BitcoinSV) are especially susceptible to orphaning.

The last time this occurred was in November 2018, when two blocks one 16MB and another 13MB in size were orphaned for being too large. At the time, BitMEX researchers also blamed bad network connectivity.

This makes for three BitcoinSV block re-organizations in six months.

BitcoinSV is a fork of Bitcoin Cash (which is a fork of Bitcoin).It raised Bitcoin Cashs block size limit from 32MB to 128MB. Bitcoins block size limit is still 1MB.

Whiteblock CEO Zak Cole told Hard Fork that when blocks become too large, they take much longer to be processed by the network than smaller ones.

The longer it takes to propagate throughout the network, the higher the likelihood of it becoming an orphan, Cole said. The larger the object, the more likely it will be that it isnt transported in its entirety and will likely have to be rebroadcast.

BitcoinSV uses Proof-of-Work to come to consensus over which transactions (and blocks) to trust. Miners essentially present their own versions of the BitcoinSV blockchain for validation.

The network accepts the longest chain of blocks as the most legitimate record of transactions, but imagine a miner mines a relatively large block and presents it to the network for validation.

Now, at the same time, another miner shares a smaller block, buttheir transactions are written to the blockchain first. In this scenario, the second miner has effectively stolen the first miners intended spot in the trustworthy longest chain.

The miner with the bigger block is stuck with no place to put it. Theyre forced to orphan the block, and the transactions inside of it are effectively cancelled. This means the block was mined, but not included in the blockchain.

While this might seem like a system working as intended, regular block orphaning could have major consequences. Cole explained to Hard Fork that devastating fork events can occur when different versions of blockchains meet with conflicting block histories.

When a significant portion of nodes receive Version A of the chain and then a similarly significant portion of nodes receive Version B, everything will go to hell, Cole told Hard Fork. If blocks are too large to propagate throughout BitcoinSVs mining pools effectively, theyre all going to be deadlocked for a period of time.

These scenarios present conditions which significantly increase the likelihood of double-spends. These attacks involve spendingcryptocurrency with intent toreverse the transactions by assuming 51 percent (or more) of the networks total computing power with a 51-percent attack.

The thing is, orphaned blocks distract network participants from working with the correct chain.Having multiple active versions of a blockchain makes for lesscomputing power dedicated to the longest version of the blockchain.

This means an attacker might not even need to control 51 percent of a networks hash power to double-spend, they could actually find success with much less.

Large portions of the available network hashing rate is going to waste, which lowers the total overall security of the network. warned Cole. As theorphan count rises, it lowers the total amount of hashing power needed to engage in a 51-percent attack.'

A number of cryptocurrency services have recently removed support for BitcoinSV, after Craig Wright and his proponents launched legal action against prominent community members one of which is a pseudonymous Twitter space-cat.

Its still unclear whether BitcoinSVs recently orphaned blocks were malicious. Cole says re-organizations arent necessarily indicative of an attack, but given the current climate, he doesnt rule out this scenario.

BitcoinSV indeed boasts a tiny fraction of Bitcoins hash power, but Cole warns fixing high orphan rates isnt simply a matter of recruiting more miners to the network.

[BitcoinSVs] block sizes are massive. Id say its not an attack, but its definitely a possibility if someone were clever enough to know how to exploit the suboptimal performance, said Cole.

Its not so much to do with hashing power as it large block times, large block sizes, and a suboptimal P2P [peer-to-peer] networking stack, he added.

Hard Fork reached out to nChain, the firm behind BitcoinSVs software, to ask about this unusual activity. Unfortunately, no BitcoinSV reps were immediately available for comment. Well update this piece accordingly should we hear back.

Did you know? Hard Fork has its own stage atTNW2019, our tech conference in Amsterdam.Check it out.

Published April 19, 2019 13:49 UTC

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BitcoinSVs blockchain is struggling with its enormous 128MB ...