We can confirm that there was a successful 51% attack on Ethereum Classic • Hacker News Board

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#151

Post by stale2002 » Tue, Jan 08, 2019, 1:34 AM UTC

AlexCoventry wrote: post #119

stale2002 wrote: post #112

Earlier quoted context omitted.

Well, the reality is that "attacking" a coin is much more difficult than just spending 3$ on something. You also have to actually do the double spend transactions, and hope that the person that you are stealing money from doesn't do anything about it. It is that step 2 that is actually much harder than a nieve attack might suggest.

Not really, you just have to short the coin in trading, then cover your short when your double-spend discredits the coin's security.

Attacking a coin, in an attempt to drive down the price, and make money on an open short that you have is very risky behavior.

Historically speaking, the effects of an attack on the price aren't that clear cut.

The price of an "attacked" coin can jump, just as often as it crashes. The narrative being "oh, there was a problem, but we fixed it! Look at how great we were at defending against an attack!".

Crazy, I know. I am just saying that it is not that simple, and a person is risking losing as much money as they might gain.

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#152

Post by lojack » Tue, Jan 08, 2019, 1:43 AM UTC

nickpsecurity wrote: post #137

lojack wrote: post #132

Earlier quoted context omitted.

> A key difference is most of the new techs like Internet, email, Paypal, and so on improved on what people already had in a way that delivered obvious value. I'd argue that for most people the value was only obvious afterwards. To put email in perspective, early adopters had to choose between what they already knew and all the hurdles involved in connecting to the internet and using the new technology. There was als…

The thing I was getting at is, if you had a computer and Internet, then email would be a free, fast alternative to traditional mail. That has obvious benefit. Whereas, these currencies are volatile, slower, often dont allow charge backs, use more energy, and accepted at fewer places. Worse in every way to checking accounts and credit cards. Esp if we have multiple cards or accounts to reduce risk of single institutio…

> if you had a computer and Internet

Thats a lot of hand waving for something that wasn't trivial at all in the 60s and 70s.

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#153

Post by butisaidsudo » Tue, Jan 08, 2019, 1:43 AM UTC

xur17 wrote: post #139

zik wrote: post #134

Earlier quoted context omitted.

It's worth pointing out that just getting 51% hash rate isn't enough to steal money. It's really just the entry point at which you _might_ be able to steal money. To actually steal money you need to falsify at least six blocks, which in turn means you need to mine six blocks in a row (roughly speaking). The probability of this being successful is (1.0-0.51)^6 - ie. about 1.5% chance of being successful. You can incre…

> You can increase your chances by increasing your mining percentage. Make it a 75% attack and you have an 18% chance of success. To have a 50/50 chance of success you really need to mount about a 90% attack which is pretty ambitious. I'm not sure this is accurate. You don't need to mine 6 blocks in a row on the existing chain. Clients are programmed to recognize the longest chain, so you just need to silently mine n…

I'm trying to understand what "cashing out" would look like in an attack like this. One option would be to send coins to an exchange as you mentioned, and I presume cash them out before publishing your longer chain.

However, after the attack wouldn't it be easy to compare both chains and see which coins were double spent? Wouldn't you obviously be the perpetrator, having both double spent, as well as having cashed out a large amount of money? Or is the idea that you'd be able to cash out to a bank account not tied to your real identity?

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#154

Post by martindale » Tue, Jan 08, 2019, 1:43 AM UTC

_n6th wrote: post #141

martindale wrote: post #140

Given enough time, chains behind the lead position will always succumb to this attack vector. Ethereum's design was flawed in other ways, but at least now it's clearly best used as the sandbox that it is.

You are aware that Ethereum Classic is not the same as the much, much higher-hashpower Ethereum chain, right?

The mining on that chain is largely pointless, as it's directly controlled by Vitalik. If I held assets on either, it'd be on the chain that didn't hard-fork to reverse a single user's transaction.

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#155

Post by xur17 » Tue, Jan 08, 2019, 1:48 AM UTC

butisaidsudo wrote: post #153

xur17 wrote: post #139

Earlier quoted context omitted.

> You can increase your chances by increasing your mining percentage. Make it a 75% attack and you have an 18% chance of success. To have a 50/50 chance of success you really need to mount about a 90% attack which is pretty ambitious. I'm not sure this is accurate. You don't need to mine 6 blocks in a row on the existing chain. Clients are programmed to recognize the longest chain, so you just need to silently mine n…

I'm trying to understand what "cashing out" would look like in an attack like this. One option would be to send coins to an exchange as you mentioned, and I presume cash them out before publishing your longer chain. However, after the attack wouldn't it be easy to compare both chains and see which coins were double spent? Wouldn't you obviously be the perpetrator, having both double spent, as well as having cashed ou…

It absolutely would be easy to compare both chains and see exactly which coins were double spent, and you'd obviously be the perpetrator. Not that I advocate it, but if you wanted to carry out an attack, you'd likely target an exchange that didn't require verification, and you might exchange and withdraw under another coin (ex: trade ETC for ETH).

Then spend and/or clean your ill-gotten gains.

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#156

Post by lokedhs » Tue, Jan 08, 2019, 1:50 AM UTC

Klathmon wrote: post #32

kryogen1c wrote: post #21

Earlier quoted context omitted.

> That's like saying "this whole programming thing just keeps on giving" every time a bug is discovered in any program. No it's not. Programming is a tool to create programs with. Block chain is a technological buzzword being used (and implemented) wildly inappropriately. 51% attacks are a fundamental vulnerability in decentralization. It would be like inventing programming when everyone pretends bugs don't exist at…

You won't find any disagreement from me that there is a LOT of garbage out there using blockchains and cryptocurrency tech inappropriately. The extreme vast majority is trash, manipulative, and awful in most every way. Not to mention the charlatans and fanboys that hype it as able to do everything and anything perfectly. But the few that use it well are doing fairly well, and innovation is happening. You shouldn't lo…

Are they though? I'm honestly curious as to what those things could be. A lot of people talk about good uses of blockchains, but all examples I've seen are either not actually good uses, or they have some flaw that makes practical implementation impossible (or at least highly unlikely).

What examples of good use of blockchains are you thinking of?

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#157

Post by jonahx » Tue, Jan 08, 2019, 1:54 AM UTC

jancsika wrote: post #108

jonahx wrote: post #81

Earlier quoted context omitted.

Would you mind elaborating on this for someone unfamiliar?

Imagine all the Bitcoin miners out there right now using their ASICs to do extremely efficient hashing in the hopes of generating a block reward. Let's didactically suppose there are 100 such miners total. Now imagine Dinkycoin comes along and releases their cryptocurrency that uses the same hashing mechanism for the block reward. Initially they have the block difficulty level pretty low as there aren't that many peo…

Terrific post. Thanks for taking the time to write it.

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#158

Post by [deleted] » Tue, Jan 08, 2019, 1:55 AM UTC

dragontamer wrote: post #150

koolba wrote: post #147

Earlier quoted context omitted.

If the attacker has 50+% of mining power for the entire duration then yes it wouldn’t work as the longer things stretch out the further ahead the attacker gets (statistically). However it the attacker has less than 50% they can still wage an attack. With 10% of mining power I’ve got a 1% chance of mining consecutive blocks. It dwindles quickly even for larger percentages and a large number of confirms makes that angl…

> However it the attacker has less than 50% they can still wage an attack. With 10% of mining power I’ve got a 1% chance of mining consecutive blocks. It dwindles quickly even for larger percentages and a large number of confirms makes that angle impractical. ETC's blockchain just had over 100+ blocks change, according to the tweet. Even with 40% of the mining power, the probability of such an event (40% mining power…

[deleted]

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#159

Post by matte_black » Tue, Jan 08, 2019, 1:58 AM UTC

vasilipupkin wrote: post #102

matte_black wrote: post #91

Earlier quoted context omitted.

It’s not very often you get a chance to take down a currency. In 30 years from now you’ll be able to brag about how back in your day you took down entire cryptocurrencies with 51% attacks.

51% attacks are quite possibly wire fraud so I would refrain from bragging about them. More accurately, trying to double spend the coins is wire fraud.

Which government will prosecute?

Re: We can confirm that there was a successful 51% attack on Ethereum Classic

#160

Post by pmohun » Tue, Jan 08, 2019, 3:10 AM UTC

theamk wrote: post #54

albertgoeswoof wrote: post #29

Earlier quoted context omitted.

There are some cool things you can do with blockchains, they’re just a little over hyped. It’s pretty neat to send funds to someone without going via a 3rd party, it’s cool to run code on a global computer, it’s awesome to have digital assets that can’t be doled out on a whim by a central authority.

... It's great when you can lose lots of money by spilling soda on your computer?* *more money than this computer's price

This is not an effective argument - you are assuming that a user of digital currency will not keep multiple copies of their money, especially in meaningful amounts.