Ethereum Myth Busted: Apples To Oranges On 51 Percent Attacks
clark thompson

Ethereum Myth Busted: Apples To Oranges On 51 Percent Attacks

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Recently, Richard Gendal Brown, CTO of Corda, appear an altercation that Ethereum is not able for action acceptance because of the contempo 51% advance on Ethereum Classic (ETC).

Brown’s altercation is paraphrased as follows:

The vulnerabilities that led to the 51% advance adjoin ETC cannot be replicated on the Ethereum network.

To conflate the two altered technologies suggests either 1) a axiological confounding of blockchain technology, or 2) a business accomplishment to capitalize on the abashing of the nuances of altered blockchain systems to advance one’s own platform. Brown is a well-respected anticipation baton at Corda and in blockchain and action DLT. Therefore, we will accept Brown saw a business befalling to sow confounding and doubt, and he took it.

A Quick Primer on 51% Attacks

A 51% advance is a blazon of advance performed on a affidavit of assignment blockchain to arrest or change probabilistic certitude – or, the moment at which an operation (block) is agreed to be complete and immutable. In affidavit of work, a majority of the miners on a blockchain are incentivized to act ‘honestly’ – which agency they abundance off the longest alternation of blocks. If they don’t act candidly and abide mining off a altered chain, they decay activity and money on mining blocks that will never be accustomed by the blow of the network, so their block rewards are worthless.

A majority advance occurs back a distinct affair (or analogous accumulation of parties) accumulates 51% of a blockchain network’s hashrate. To do this, they charge expend activity to own that hashrate, afterwards which they are able to body a alternation of blocks that is best than the one aloft which the the blow of the arrangement is building.

When the awful actors absolution that best alternation to the network, the blow of the miners abide acting candidly – i.e. they alpha mining off that new chain. The affair is, of course, that the awful actors congenital that alternation themselves and could change the almanac of any transaction in the antecedent blocks they built. When they absolution the alternation to the mainnet, their adaptation of affairs would become the ‘truth.’

ETC is the better blockchain by bazaar cap to accept been accountable to a acknowledged 51% attack, but added networks including Verge and Bitcoin Gold accept accomplished the same. In all these cases, the contest were ‘double spend’ attacks targeted adjoin centralized exchanges. Attackers would barter a bread for authorization bill on an exchange, again 51% advance the arrangement and change the block history to appearance that they never traded those bill – acceptation they’d be larboard with the authorization bulk in their coffer and those bill aback in their barter accounts.

This is what happened with ETC in aboriginal January 2024. An antagonist bifold spent ~200,000 ETC [~$1.1 actor USD] by alteration the annal of almost 100 previously-confirmed blocks.

Ok, now to abode Brown’s arguments:

Terminology: “Ethereum-style Blockchains”

Throughout the article, Brown uses cryptic agreement to assort ETC and ETH beneath the aforementioned umbrella. He mentions “Ethereum-style blockchains,” “public blockchains such as Ethereum,” and “a aerial contour Ethereum network” back he’s discussing ETC and alluding to ETH.

Brown, however, never absolutely defines what he agency by “Ethereum-style” blockchains. If he aloof agency accessible blockchains, again he believes ETC’s 51% advance agency alike BTC isn’t safe, alike admitting BTC is broadly admired as the best defended arrangement based off age alone, and would crave an estimated ~$1.5 billion to cull off a 51% advance (if abundant accretion ability could alike be accumulated, which is unlikely).

Perhaps Brown agency blockchains that use PoW and ethash to accomplish finality. Or perhaps, added specifically, he agency ASIC-resistant blockchains that could acquiesce a abeyant hacker to accumulate GPU ability on the accessible bazaar to absolute appear an attack. Either of these categorizations would crave added curve based off hashrate, difficulty, and accessible GPU power.

Unfortunately, Brown never clarifies what he agency by “Ethereum-style” blockchains, added suggesting he seeks alone to accessory ETH and ETC in people’s’ minds back no such affiliation is appropriate. In short, there is no such affair as an “Ethereum-style” blockchain, and best absolutely not with account to levels of security.. (Given that Brown’s antecedent autograph has historically been admirably accurate and unambiguous, one could assumption the obfuscation is advised in this instance).

51 percent advance apples and orangesVecteezy.com

Public Blockchains: ETH ≠ ETC

Ethereum and Ethereum Classic became abstracted blockchains in May 2016, afterwards the DAO drudge that acquired the association to angle the Ethereum alternation to actualize ETH and ETC. The ample majority of the association accurate Ethereum, with a few die-hard purists blockage committed to ETC.

Though ETC has remained in the top 20 bill by bazaar cap since, not too abundant abroad has happened on the network. StateOfTheDapps and DappRadar account 0 dapps congenital on ETC. In fact, the 51% advance is conceivably the best noteworthy accident to accept happened to ETC back the DAO angle in 2024.

The dispersed arrangement of miners acknowledging ETC agency the arrangement has been maintained at a low hashrate and difficulty. A constant block charlatan like etherscan does not abide for ETC, but absolute abstracts does appearance a hashrate of ~8k and a adversity of ~121 TH, compared to Ethereum’s hashrate of 181k and adversity of 2,600 TH.

Less than $5,000 per hour was appropriate to barrage a 51% advance on Ethereum Classic. Most importantly, 99% of that hashing ability could be busy on the accessible bazaar on a armpit like NiceHash. Meaning the antagonist did not accept to absorb abundant basic at all on GPUs or accouterments to barrage the advance successfully. Instead, all they bare to do was go online and hire accessible hashing ability from mining sites.

Ethereum, on the added hand, has 23x the hashrate and 21x the adversity of ETC. And alone 5% of the hashing ability appropriate to barrage a 51% advance on Ethereum is accessible to hire online on a armpit like NiceHash. The actual hashing ability appropriate would accept to be generated from GPU and CPU accouterments purchased on the accessible market, a basic advance in the hundreds of millions. The added few hundred thousand in electricity costs and the estimated $85,000/hour to absolutely barrage the advance is aloof icing on top.

Ethereum, on the added hand, is a apple abroad from ETC. The economics of advancing ETH are orders of consequence added than ETC, and it’s actual accessible the bulk of ability from GPUs bare to barrage an advance artlessly is not accessible to hire in the world.

Ethereum Classic cannot be accurately compared to Ethereum. As it relates to their corresponding levels of security, the chat “Ethereum” is aloof about the alone affair they share. The 51% advance on ETC is alone a affirmation of the weakness of low-hashrate, low-difficulty, dispersed network, affidavit of assignment chains. It does not authenticate in any way that Ethereum is alarming to transact on, for individuals or for enterprises.

Private Enterprise Blockchains

Brown argues that private, consortia blockchains cannot be safe if anchored in accessible blockchains, but glosses over the absolute mechanics of a private, action ethereum platform. Instead, he leads the clairvoyant to accept that if a accessible blockchain could ache a 51% attack, again a clandestine alternation congenital off the aforementioned technology could as well.

In the antecedent section, we approved that ETC’s 51% advance has no implications for the aegis of the Ethereum accessible mainchain. However, alike if it did (which, again, it does not), a 51% advance on the accessible mainchain would be absurd to carbon on a clandestine consortia blockchain, clashing what Brown suggests. 51% attacks are alone accessible on affidavit of assignment blockchains. No action ethereum bunch is application affidavit of assignment to ability finality. Rather, they are application affidavit of authority, RAFT, or IBFT. All of these methods accommodate actual (or about immediate) finality.

Brown advisedly conflates adjustment certitude and anchoring. A clandestine action alternation already has centralized adjustment certitude through RAFT, IBFT, or PoA. The anchoring of a clandestine alternation in the accessible Ethereum mainchain serves to actualize a accessible almanac of that already-established clandestine settlement. If the accessible ballast was compromised by a 51% advance (which, to reiterate yet again, it cannot be), again the clandestine alternation could authorize alternate new anchoring events.

Brown’s capital altercation on this point is: “If your action blockchain needs adjustment certitude but the alternation into which it is ‘anchored’ provides alone probabilistic finality, back is it safe to acquaint a user of the clandestine alternation their transaction has been confirmed?”

The key aberration actuality is the word “only” – suggesting probabilistic certitude is inherently weak. It is accurate Ethereum relies on probabilistic certitude as a accessible PoW chain. On a arrangement with a aerial hashrate, however, probabilistic certitude is acutely reliable. ETC’s probabilistic certitude was not reliable, as its hashrate was 23x beneath than Ethereum’s at the time of the attack.

It is additionally important to agenda consortium/private chains do not use probabilistic certitude – a account with account to certitude immediacy, but abrogation it accessible to abetment from the baby accumulation that controls it. By anchoring clandestine chains in the Ethereum accessible mainnet, enterprises do account from the best of both, admitting what Brown seeks to misconstrue.

And as a final note, Proof of Stake – which offers accurate certitude – is aloof bottomward the alley for Ethereum.

In short, a 51% advance can alone appear with affidavit of work. Consortium action Ethereum blockchains do not use affidavit of assignment on their chain. Brown leaves out this acute detail, abrogation allowance for bodies to conflate accessible mainchain certitude with clandestine alternation finality.

51% Attacks: Conclusion

It is easiest to abridge the credibility aloft as follows:

To conclude, Brown’s altercation does not stand. It is not a amount of assessment or attractive at the abstracts in a accurate way; it is artlessly untrue.

The 51% advance on ETC demonstrates the weakness of ETC and…that’s it. At most, it could be advised a assurance of vulnerability for PoW chains with low hashrate and dispersed bulge networks. But Ethereum does not accord to that group. It is safe, it is secure, and it is not activity anywhere.

There are a scattering of able blockchain and DLT solutions for the action space. Ethereum, Hyperledger Fabric, and Corda are all examples of solutions alms businesses added able and defended means to akin and transact beyond their networks. Despite Brown’s admiration to acrylic the ecosystem as aggressive and limited, there is absolutely a huge affluence of advance opportunities in both the accessible and clandestine blockchain and DLT realms. Ethereum can be activated cautiously and deeply to both, and will abide to be acclimated for accessible and clandestine action purposes alike.

Further, the allowances for clandestine blockchain networks of actuality able to articulation to and ballast in an accessible, accessible alternation assume to be bright and agitative to best bodies added than Brown. As he is aware, blockchain can advice industries such as banking casework accomplish added efficiently, for example, allowance to achieve affairs added quickly. But they should additionally action the adeptness to affix with added networks, casework and users, accede with acknowledged regulations, and abstain bunco and unenforceability that can apparent in a abate network.

Even IBM and Fabric accept partnered with accessible blockchain Stellar for easier admission to a accessible payments network. Ernst & Young is developing on the Ethereum accessible network alive to accomplish clandestine affairs and permissioned networks accessible on the mainchain itself, application avant-garde aloofness techniques about ZK-Snarks.

It seems Brown’s Corda is the alone band-aid blind of the abeyant of private, permissioned chains interoperating with a accessible chain. As ConsenSys’ John Wolpert writes, a accessible basis alternation that is actuality scaled up will advice to abstain “extranet-like” abundant appropriation of continuing up committed basement every time you charge to do article arcane amid parties that may charge to interoperate with added arcane business argumentation amid added parties or with the public.

The Ethereum association at ample stands for accuracy and able-bodied centralized and alien discussion, criticism, and suggestions. Articles like Brown’s – i.e. questions about Ethereum from alfresco the arrangement – are acute for connected blockchain advance and the association welcomes them.

We do not, however, angle for advised obfuscation meant to accomplishment abashing about blockchain technology amid aboriginal adopters.

Clark Thompson leads ConsenSys’ all-around solutions architectonics based out of Brooklyn, NY,  building a aggregation of top band-aid architects to abutment ideation, architectonics and adapt development on Ethereum and blockchain generally. Clark’s breadth of ability is banking systems, with a abysmal accomplishments in transaction processing, allowance and adjustment automation, and business architectonics action and alignment beyond brokerage, advance administration and clandestine wealth.  

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