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

#21

Post by kryogen1c » Mon, Jan 07, 2019, 9:33 PM UTC

Klathmon wrote: post #6

hacker_9 wrote: post #3

Amazing, this blockchain technology really just keeps on giving. I have to say, it's quite entertaining to watch. It's pretty much a car crash happening in slow motion at this point. At least it provides something else to nerd joke about by the watercooler that isn't brexit for once.

That's like saying "this whole programming thing just keeps on giving" every time a bug is discovered in any program. Those involved have been warning of the insecurity of smaller chains for a long time now, and they aren't representative of the entire ecosystem.

> 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 all. Bugs are inherent to the task, just like blockchains have a very narrow set of use cases, but everyone's too busy flying too close to the sun.

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

#22

Post by semi-extrinsic » Mon, Jan 07, 2019, 9:35 PM UTC

johndunne wrote: post #7

This is inevitable. Ethereum Classic (ETC) isn't the only currency such attacks have been successful on. The site https://www.crypto51.app/ puts the cost of running a 51% attack on ETC at ~$5k per hour. The incentive for running these attacks for profit becomes higher as the market cap of these coins increases, making long-term 'investment' in these coins nonsensical.

How can there be coins with $5M+ market cap where the cost of a 51% attack is $3.00 ?? In an efficient market, thieves should just immediately attack that. Or is the benefit too low?

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

#23

Post by brianwawok » Mon, Jan 07, 2019, 9:39 PM UTC

NathanCH wrote: post #18

johndunne wrote: post #7

This is inevitable. Ethereum Classic (ETC) isn't the only currency such attacks have been successful on. The site https://www.crypto51.app/ puts the cost of running a 51% attack on ETC at ~$5k per hour. The incentive for running these attacks for profit becomes higher as the market cap of these coins increases, making long-term 'investment' in these coins nonsensical.

Some of these numbers are very low. $30/h for Bitcoin Private? Seems inexpensive, what am I missing?

No one uses it. So you attack it. Cool. You can't turn it into USD or anything else, so you just spend $30 for nothing.

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

#24

Post by leevlad » Mon, Jan 07, 2019, 9:39 PM UTC

orblivion wrote: post #11

bonyt wrote: post #8

Earlier quoted context omitted.

In this kind of blockchain network, the longest chain of blocks is considered to be the valid one. However, someone that has 51% of the hashing power (i.e. more hashing power than everyone else combined) can create a chain that grows faster than the chain used by everyone else. This means that they could tamper with their chain, potentially rewriting history on it, and because it is the longest chain, it will be acce…

Being only somewhat familiar, I wonder this: Why don't clients have a simple rule against accepting changes to history that are more than one or two blocks old?

Because it's an eventually consistent system. If what you proposed was implemented, you could end up with a fork that would never get reconciled.

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

#25

Post by pietjepuk88 » Mon, Jan 07, 2019, 9:39 PM UTC

aetherspawn wrote: post #2

What does this mean? (Not all of us know a whole lot about how crypto works or why this is good or bad and what it means for our investments)

The most typical way to profit from this, is to have quite a bit of ETC, and then sell it on an exchange or buy something expensive. This transaction would then end up on the block chain, and eventually be considered secure / part of history.

Privately, you are building a chain where said transaction did _not_ occur. Because your hash rate is high enough, you are generating blocks at at least the pace of the public chain. You keep mining your chain (without your transaction) privately until the bank transfer from the exchange goes through, or you are sure whatever you bought is on its way. Then you broadcast your private chain as soon as it has at least one block more than the public chain and voila, you have your ETC back and the USD/EUR/crypto you sold it for (or the product you bought). You can have your cake and eat it too. This is because the rule of most cryptocurrencies is that the longest chain is the truth, and everyone mines on top of the longest chain. If a longer chain appears out of nowhere, all miners will jump on top of this one. There is no such thing as "finality" in most cryptocurrencies, where something becomes actually (read: much more) irreversible.

Of course, doing this only makes sense if what you gain outweighs the costs of performing such an attack.

Note that you typically _cannot_ steal coins from specific wallets, as you do not have the keys to those coins. You can however censor transactions that you may not want, but the above is a common way to benefit from a 51% attack.

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

#26

Post by ceejayoz » Mon, Jan 07, 2019, 9:42 PM UTC

semi-extrinsic wrote: post #22

johndunne wrote: post #7

This is inevitable. Ethereum Classic (ETC) isn't the only currency such attacks have been successful on. The site https://www.crypto51.app/ puts the cost of running a 51% attack on ETC at ~$5k per hour. The incentive for running these attacks for profit becomes higher as the market cap of these coins increases, making long-term 'investment' in these coins nonsensical.

How can there be coins with $5M+ market cap where the cost of a 51% attack is $3.00 ?? In an efficient market, thieves should just immediately attack that. Or is the benefit too low?

There's no demand for those coins. $PAC may have a $5M market cap, but it had $6,500 in volume in the last 24 hours. Some (most?) of that volume is likely to be people just moving stuff around rather than actual buying/selling between people.

You might get rich on paper, but good luck getting anyone to help you convert your riches into spendable currency.

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

#27

Post by leevlad » Mon, Jan 07, 2019, 9:42 PM UTC

soared wrote: post #19

According to [1], running a 51% attack for an hour is incredibly cheap for most currencies. Why doesn't this happen more often, or is running the attack for an hour not a long enough time frame to double spend? [1] https://www.crypto51.app/

I think it's just not worth the time. What do you do when you've successfully run a 51% attack? You go on an exchange and double spend the money, which means you have to maintain the 51% attack for longer than min # of confirmations for this currency on said exchange. And even after that, most exchanges (in NA at least, can't say much about intl) require KYC.

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

#28

Post by johndunne » Mon, Jan 07, 2019, 9:48 PM UTC

NathanCH wrote: post #18

johndunne wrote: post #7

This is inevitable. Ethereum Classic (ETC) isn't the only currency such attacks have been successful on. The site https://www.crypto51.app/ puts the cost of running a 51% attack on ETC at ~$5k per hour. The incentive for running these attacks for profit becomes higher as the market cap of these coins increases, making long-term 'investment' in these coins nonsensical.

Some of these numbers are very low. $30/h for Bitcoin Private? Seems inexpensive, what am I missing?

You're not missing anything. The coins are literally worthless other than to those who trade them on crypto exchanges, to steal each other's lunch money. Plus, launching an attack isn't just a case of paying $30 per hour. You need to have a client able to perform whatever your aim is for the attack, which requires a level of coding knowledge. And dev's at that level of knowledge are probably earning real money for their time.

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

#29

Post by albertgoeswoof » Mon, Jan 07, 2019, 9:52 PM UTC

kryogen1c wrote: post #21

Klathmon wrote: post #6

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. Those involved have been warning of the insecurity of smaller chains for a long time now, and they aren't representative of the entire ecosystem.

> 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…

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.

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

#30

Post by johndunne » Mon, Jan 07, 2019, 9:52 PM UTC

leevlad wrote: post #27

soared wrote: post #19

According to [1], running a 51% attack for an hour is incredibly cheap for most currencies. Why doesn't this happen more often, or is running the attack for an hour not a long enough time frame to double spend? [1] https://www.crypto51.app/

I think it's just not worth the time. What do you do when you've successfully run a 51% attack? You go on an exchange and double spend the money, which means you have to maintain the 51% attack for longer than min # of confirmations for this currency on said exchange. And even after that, most exchanges (in NA at least, can't say much about intl) require KYC.

Exactly, it's not worth the time. And once the attack is underway, it'll be detected and everyone can simply increase the number of confirmations needed before finalising.