Can the blockchain be hacked? Ask again.

[worldofcoins]

Talking about bitcoin’s blockchain; when a miner is trying to alter the ledger, other miners following the correct rule-see this and decline to accept the change. And as a result, the bad guy's work is pointless. At least 20% of the hashrate is now owned by publicly traded corporations, making it impossible for a miner with 51% of the hashrate to launch an attack quickly in a matter of seconds.

The 51% attack and you mentioned is about replacing an older blocks with another valid block meaning they both follow the same "correct rule" since they are both valid. You can't reject such blocks. Also technically it is not the miner rejecting invalid blocks, it is the node.
The reason why 51% attack doesn't work is because how decentralized the mining in bitcoin is. It is not possible to gain control of that much hashrate.

These days it's nearly impossible to perform that 51% hash rate attack after looking at the hardware different people are using and not at the same place.

I 'd like to know in 140 yrs when bitcoin wouldn't be mineable then how would this 51% attack be still work?, I mean at that time there will be no blocks to mine only transaction fees. but then transactions wouldn't be inside blocks.

[BlackHatCoiner]

I 'd like to know in 140 yrs when bitcoin wouldn't be mineable then how would this 51% attack be still work?

It'd be normally "mineable". Mining won't stop after a certain block. The only thing that is dropped to 0 is the block subsidy, and will happen in 120 years. 51% attack has nothing to do with it, and will always be possible to accomplish (although, unlikely) as long as there's the Bitcoin network.

[tjtonmoy]

As for me, I don't totally trust everything available on the internet. Everything on the internet is made of codes. If you are capable enough, then you can temper with the code to hack. So it's not impossible to get hacked. So the blockchain still remains in a 50/50 chance. If one day anyone can find the abck door to the codes, then yes it's possible. But we have to live with what we can get for now.

[Sandra_hakeem]

The blockchain-- as much as I know -- is not vulnerable but, that's equally to some point.  It is ALMOST impossible to hack into a priv blockchain than a public one.
It is generally known that everything Is made out of coded instructions to function and it could equally be altered. _{that's only if miners and cyberspace securities ain't doing anything as to the adjustment of those coded instructions to sync for utmost security}
Don't you think that hackers have had the conception of attacking the blockchain over the years? Why haven't they succeeded, atleast for once? So that implies as an impossibility.

Cheers,
Sandra👩‍🦱

[worldofcoins]

The only thing that is dropped to 0 is the block subsidy, and will happen in 120 years. 51% attack has nothing to do with it, and will always be possible to accomplish (although, unlikely) as long as there's the Bitcoin network.

This is what I was wondering about, In past replies, some were stating miners will only earn through transaction fee commissions, and I think there was hardly any reply focusing on dropping the block reward in btc fractions.
If the case of bitcoin reaching above 120 years occus then bitcoin should have at least 20Trillion marketcap, which is a very good possibility and I think can be achieved.

[DooMAD]

As for me, I don't totally trust everything available on the internet. Everything on the internet is made of codes. If you are capable enough, then you can temper with the code to hack. So it's not impossible to get hacked. So the blockchain still remains in a 50/50 chance. If one day anyone can find the abck door to the codes, then yes it's possible.

Finding a backdoor would not allow you to go back and edit past blocks.  It doesn't work like that.  And if you modified code that lead to a new block being created which doesn't conform to the consensus rules in everyone else's code, that new block would be rejected.  You would have to simultaneously hack every mining and non-mining node, all around the world, at the exact same time, which (in Bitcoin, at least) literally no one is capable of pulling off.  And then you would have to hope no one noticed, which someone invariably would.  

50/50?  More like 1 in 50,000,000,000,000,000,000,000,000.

[Dunamisx]

As for me, I don't totally trust everything available on the internet. Everything on the internet is made of codes. If you are capable enough, then you can temper with the code to hack. So it's not impossible to get hacked. So the blockchain still remains in a 50/50 chance. If one day anyone can find the abck door to the codes, then yes it's possible. But we have to live with what we can get for now.

How are we expected to live by what we get when we exercise fear and doubt in the network, the technology in blockchain development is so strict that it has protocols that it's built on, if the blockchain isn't like the one way systems we have with banks then if has it distribution across every connected system all over the world within it network to bear witness with thesame information, i believe there's much to say about immutability since there's no single computer system controlling the whole affairs of the blockchain technology.

[pooya87]

These days it's nearly impossible to perform that 51% hash rate attack after looking at the hardware different people are using and not at the same place.

It is not exactly because of the hardware that people use though. It is mainly about how hard it is to acquire as many number of that hardware. For example back when people were mining bitcoin with GPUs it was still impossible to perform a 51% attack because there were no better hardware like ASICs to provide much higher hashrate so you still had to buy a large number of GPUs to gain 51% of the hashrate and that was impossible.

[tjtonmoy]

How are we expected to live by what we get when we exercise fear and doubt in the network, the technology in blockchain development is so strict that it has protocols that it's built on, if the blockchain isn't like the one way systems we have with banks then if has it distribution across every connected system all over the world within it network to bear witness with thesame information, i believe there's much to say about immutability since there's no single computer system controlling the whole affairs of the blockchain technology.

I do not know much about the technology behind this whole system of blockchain. So ignore me if I'm wrong somewhere. It just that the thing in internet, everything is connected by something. if one can make something, then others can destroy that too. But as you said, it is strict. So we are safe for the time being. Let'as just hope for the best and hope it stays the same way. That's all i can say now.

[minairia3]

As for me, I don't totally trust everything available on the internet. Everything on the internet is made of codes. If you are capable enough, then you can temper with the code to hack. So it's not impossible to get hacked. So the blockchain still remains in a 50/50 chance. If one day anyone can find the abck door to the codes, then yes it's possible. But we have to live with what we can get for now.

If you talk about the future, you might be right, because the internet is essentially man-made, so one day someone smarter enough than satoshi can decipher the current blockchain codes, no what is impossible. But now I can say that it is very safe to talk about the bitcoin blockchain.
If it's really insecure and can be hacked the way people are assuming, then I think the government has found a way to destroy bitcoin instead, they must be having a lot of headaches in finding a way to ban it like now.

[lucates]

A recent discussion brought up in my locale board lead me to this little striking detail from my research that holds a contrary opinion to what most know about the blockchain.

Blockchain isn’t totally foolproof — there are a few ways that it can be hacked. “If 51% of the network of miners, or of work done by miners, is bribed to alter the ledger, this can result in corruption and incorrectness in the ledger.” Additionally, if one of the nodes of the blockchain network is disabled and it cannot communicate, it may be compromised

SOURCE

This is not to undermine the strength of the blockchain technology and make it less of what it is, but for us to discuss the possibility of this happening and the credibility of this information.

Kindly share your opinion.

In my opinion, the currently most reliable and unhackable technology is block chain technology. In every transaction, has been creating a new block by adding ID and hash code to the block. It gets rid of fraud and manipulation because each block is connected. So block chain technology is accountable, strong and proven. Every miner makes this system secure by creating a decentralized ledger.

[franky1]

The only thing that is dropped to 0 is the block subsidy, and will happen in 120 years. 51% attack has nothing to do with it, and will always be possible to accomplish (although, unlikely) as long as there's the Bitcoin network.

This is what I was wondering about, In past replies, some were stating miners will only earn through transaction fee commissions, and I think there was hardly any reply focusing on dropping the block reward in btc fractions.

you cannot change bitcoin rules with a 51% attack. you can only change transaction lists by going back and re-doing a block and subsequent blocks to catch up and over take the network to push your version of block transaction lists as the master chain to follow
where the re-done block has different transactions

in 120 years where the only mining income is from transactions.. it then becomes less likely risk of "empty blocks" because having no transactions = no income

however.
if the only income is transactions.. and thus if the total fee's are not totalling a high enough amount to make it expensive to compete on the network. thus not expensive to then re-org.. then that cheap attack makes it easier to perform than now.

so in the next 120 years we really need to push that total fee's per block are substantial amount to not make it cheap to attack.
..
this does not mean make each user pay alot more. as that just makes people not use the network and not do transactions.. but instead increasing the transaction count so the total fee's increase without hurting the average fee per user

now you might understand why scaling bitcoin ONCHAIN is more important than the silly games of "offramping"(removing) users

less users using bitcoin, and those remaining having to pay increasing fee's does not help bitcoin at all for MANY reasons
..

If the case of bitcoin reaching above 120 years occus then bitcoin should have at least 20Trillion marketcap, which is a very good possibility and I think can be achieved.

it does not matter if bitcoin market cap is $20tril because
if a user is having to pay more then a weeks wages to transact. they wont use it. no matter the market price/cap of bitcoin is.

oh and in 120 years.. the "dollar" of 20trill, might be hyperinflated to only be 3 months wage

thus you might even be looking at a market cap of 20 quintillion
where a single users transaction is 1.5trillion (weeks wage)
like how the Zimbabwe dollar hyper inflated

but no one would use bitcoin if fees were a weeks wage due to no ONCHAIN scaling to dilute fees down while offering extra transaction count (as what was demanded in 2014+ as the progress bitcoin should follow)
africa has 1 billion people. but how much % do you think would use a bitcoin onchain transaction when 35cent is a days wage. and $1.50 is a weeks wage
americ and UK still love bitcoin because 35c-$1.50 is just 2-10minutes of minimum wage. which americans and UK people think is the appropriate cost for a 10min transaction

im biitish but i can put my acceptable levels aside and see the issues third world countries have and also the risks in the future if fee's increase and scaling does not

[Dunamisx]

if one can make something, then others can destroy that too

This is muchly a case that happen to a centralized development whereby the success of an invention does not maintain being attributed to a single person but a collective efforts, in doing this, things might not work for the unity of them all with time and everyone tend to break up to stand independently, here things go wrong alot of ways because everyone will always strive for survival of which many use a counter oppositions against the other, that's why it's been taught that blockchain is a decentralized network itself unlike other networks connected to a central server.

[Dzwaafu11]

They can't edit the blockchain talkless of hacking you know blockchain is a very strong technology use to transfer btc in the global so I think to hacked blockchain must be a very difficult thing for someone to do.
And we don't even pray for such.