Malibuflyer wrote:
Faking the past is impossible, right. Spending somebody else’s bitcoin is simple if you own the majority.
Faking the past is only possibel if you have enough hashing power to rewrite the blockain from a certain point in the past and then overtake the rest of the world. So if you do that for a second ago some amount north of 50% might be enough. If you want to start further back you will need even more performance.
Spending somebody else’s bitcoin is simple if you own the majority.
I think there is some confusion here. The first thing is a 51% attack which as was written by others can only be used to double spend ones own coins or starve the network. This would require 51% (in real life probably more to be reliable) of the hash power. Other nodes in the network will let you get away with this unless there is human intervention.
If you want to take other peoples coins this would usually require a so called hard fork. You have to make most people in the network change their software so it validates your new tampered version of the blockchain. This can not be done with 51% of hash power but you will have to convince enough users, so coin owners, miners, vendors selling products in exchange of bitcoin, bitcoin trading platforms etc. In the case of Bitcoin such a project would probably require Satoshi Nakamoto himself to speak up.
One exception I am not sure about would be to stage a 51%+X attack so strong that you can go all the way back when a coin was actually mined, change that block and then attribute all to yourself. That might work but the required hash power would be huge.
You are technically correct. They can not take it away – what they can do, however, is to a) reroute the original transfer to one of their wallets and b) prevent that you can ever do anything with “your” btc.
Therefore the statement “nobody can take it away from me” is as valid as “they can’t take money from my account as my printed account statement is in my vault and nobody can change it” in traditional banking.
Cobalt wrote:
Given the massive power required to do that, the theory is that it is actually much more economical to just mine bitcoin with that power because you can’t really make much money of a 51% attack – it is almost purely malicious.
This is assuming that all parties in bitcoin are purely economic driven. It fully ignores the fact that some have political interests.
Off_Field wrote:
You’re repeatedly wrong on this as you don’t seem to understand that having 51% of the hashpower mining does not give you carte blanche to rewrite the software and do whatever you like.
Oh yes, it does …
Off_Field wrote:
The protocol is well understood in what it can be done and what is needed to validate. The best that miners can do
… is change the protocol (as has happened with bitcoin cash or bitcoin gold). The only difference is that in these cases it was a minority that forked.
I can only repeat myself: The whole point about Bitcoin (and other schemes) is that there is nor external truth and no regulatory body that defines what is right or wrong but at any given point in time the majority of miners define truth.
Therefore the fact that the historic part of the blockchain can not be altered – while it is true – is completely worthless as it is the majority of the miners today who define how it is read/used. If the majority of the miner decide we just ignore blocks 680000 to 687567 that is what they do. And there is no “higher power” that could tell them that this is wrong…
Malibuflyer wrote:
This is assuming that all parties in bitcoin are purely economic driven. It fully ignores the fact that some have political interests.
Jup – hence I wrote that a 51% attack is almost purely malicious, it is not to gain coin benefit, but to destroy the currency.
There are other, computationally cheaper and easier ways to destroy a cryptocurrency. Ultimately it is a trusted network made from untrusted nodes, anything that destroys the trust in the network takes the currency down. Making it impossible to exchange BTC for anything but BTC. Attacking the exchanges and wallet providers. Simply filtering crypto protocols going through ISP nodes or crossing borders, completely fragmenting the chain in multiple duplicates etc. etc.
So in short – I think your concern and skepticism is entirely warranted, but the threat isn’t 51% of the hashing power being told by some government what to do.
Or in other words – although the explanation ‘the air above the top of the wing goes faster so it takes the same time as the air at the bottom of the wing and both streams join up’ is wrong, the aircraft still flies… ;-) SCNR
Malibuflyer wrote:
You are technically correct. They can not take it away – what they can do, however, is to a) reroute the original transfer to one of their wallets and
No they can’t.
They don’t have my private key so cannot sign the movement. Even if they are faking transactions to double spend they still need to look “legit” and pass the hashchecks.
Malibuflyer wrote:
Oh yes, it does …
Oh no it doesnt :)
Malibuflyer wrote:
… is change the protocol (as has happened with bitcoin cash or bitcoin gold). The only difference is that in these cases it was a minority that forked.
Yes the btc cash and gold are separate from the Bitcoin blockchain. This isn’t changing the protocol, it’s forking off a separate system / modified clone.
And when it comes to getting changes into the protocol, I think the recent taproot approval for implementation needed something like 90% approval rate to make the change.
Malibuflyer wrote:
at any given point in time the majority of miners define truth
I would not agree to that. In fact I think it is not mainly the miners but the people accepting Bitcoin in exchange for US dollar, Tesla cars or “other” things who judge. If you create a fork and all those people are still giving you dollars or equivalent for tokens your fork project did work out and miners will most probably follow the money. So in the end it comes down to marketing.
As we have a nice selection of critical minds here an idea which was lately discussed with a few friends was this design:
The transactions get validated by a computer located on a spacecraft. Fully open source hard and software and no possibility for any updates after launch. This way the transactions could be processed very efficiently and with minimal environmental footprint (after launch). External intervention would be extremely difficult as there is no physical access, the spacecraft has autonomous power supply and radio communication would be very hard to cut off. To account for in orbit failures probably 5 spacecraft would be required and a transaction would become final if validated by at least 3. With enough budget even all 5 could be designed by different teams so any bugs affecting more than 2 and thus breaching security would be extremely unlikely. Would you trust such a system?
No, after China demonstrating that they can destroy a satellite in orbit with a targeted attack, I wouldn’t put my wealth in it.
And not being able to do updates has more downsides than upsides. This is exactly the problem of embedded systems in critical infrastructures, which have been doing their work sometimes for decades, but were never designed to be patched because the assumption was they would remain well isolated from the outside world/Internet. Afterwards, someone wants to not drive out to each substation for routine maintenance, and connects part of it to some “remote access box”, and the trouble starts.
Most security problems of crypto systems also lie in the implementations around them. The algorithms may be very secure, but the applications around them are much harder to scrutinize for security flaws because they are more complex and evolve much quicker. In your satellite scenario, you still need to communicate with them in a 100 % secure way for this to work.
Sebastian_G wrote:
n fact I think it is not mainly the miners but the people accepting Bitcoin in exchange for US dollar, Tesla cars or “other” things who judge.
Another big Hoax – there has never ever been anyone (documented) who accepted bitcoin to pay for Tesla cars.
A well known Twitter-Star announced that to boost the exchange rate after he bought a significant amount of btc himself but it actually never happened. Yes, The Tesla Website (controlled by this Twitter Star) said the same, but actually it was never possible to buy an actual car for Blockchain – a scam within the scam. The small print of the “offer” that was online for less than a week was, that at any given point in time the buyer owes the dollar amount so you theoretically could transfer an amount of btc to Tesla but they would not accept it as payment but all they offered was to try to convert it into USD on your behalf. If it was successful and if the dollar amount they got was at least the price of the car they would be fine. If they had not realized the price of the car in dollar, you would still owe them the difference.
In that very way, I hereby publicly announce that I accept peanuts as payment for brand new Cirrus airplanes!
Off_Field wrote:
Even if they are faking transactions to double spend they still need to look “legit” and pass the hashchecks.
The “Hashcheck” is a piece of code that runs on the client. If the majority of clients decide that the result of the hashcheck for this specific transaction is positive, it is. The maths do not matter.
I have a hard time to understand how the people promoting bitcoin fail to see that its very concept is that the majority is always right.
Off_Field wrote:
Yes the btc cash and gold are separate from the Bitcoin blockchain. This isn’t changing the protocol, it’s forking off a separate system / modified clone.
What is “the clone” and what is “the original” is defined by the majority. If the majority of miners would have gone for the btc-cash protocol, we would no call btc-cash “the original” and the remainders of the original protocol “the clone”.
Sebastian_G wrote:
So in the end it comes down to marketing.
Could not agree more! Like in any ponzi scheme…
Rwy20 wrote:
Most security problems of crypto systems also lie in the implementations around them.
Absolutely! Plus in how people use them. Most people who beliefe they own btc do not actually own them but have a vostro account at a more or less reliable totally unregulated bitcoin bank w/o access to the actual btc. Most people are actually surprised that if they want to directly transfer btc they need 350GB of blockchain data on their computer (and there is not a single solution to handle btc on mobile devices w/o an intermediary..)
If you want to get rid of your Bitcoins you could buy this airplane
https://www.planecheck.com/aspdet.asp?nr=51357 local copy
;-)
