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Title: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 04:40:54 AM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack.
Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: koelen3 on February 28, 2015, 05:08:39 AM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting 51% attack means To own the 51% of hashing power over all not 51% of btc Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: sandy47bt on February 28, 2015, 06:41:57 AM If you keep buying bitcoin, it will be more expensive.
And you will reach point where you can't buy bitcoin since bitcoin price is too expensive. Maybe you will like The Hunt brothers who trying to buy as many silver as they can Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: Lauda on February 28, 2015, 06:47:07 AM 51% attack means To own the 51% of hashing power over all not 51% of btc When a coin is POW, yes, but POS is different. POS is vulnerable to a 51% shareholder attack. Honestly I don't believe that this could be done. Good luck finding 7 million Bitcoin to buy.Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: stopsigningbitch on February 28, 2015, 06:53:56 AM 51% attack means To own the 51% of hashing power over all not 51% of btc When a coin is POW, yes, but POS is different. POS is vulnerable to a 51% shareholder attack. Honestly I don't believe that this could be done. Good luck finding 7 million Bitcoin to buy.You have it wrong. You don't need 51% of the total coins to do the attack. You just need 51% of the total staking coins to do the attack(which is much lower than 51% of the total coins). Thats why PoS is not as secure as PoW. Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 07:07:01 AM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting 51% attack means To own the 51% of hashing power over all not 51% of btc the whole point is to consider this this if Bitcoin switched to Proof of Stake (POS)... so not about hashing power...but the number of units my curiosity is what people think the cost of buying the coins would be if it was POS Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 07:11:54 AM 51% attack means To own the 51% of hashing power over all not 51% of btc When a coin is POW, yes, but POS is different. POS is vulnerable to a 51% shareholder attack. Honestly I don't believe that this could be done. Good luck finding 7 million Bitcoin to buy.You have it wrong. You don't need 51% of the total coins to do the attack. You just need 51% of the total staking coins to do the attack(which is much lower than 51% of the total coins). Thats why PoS is not as secure as PoW. That's a good point.. though that seems to be alleviated by things like "balance leasing" Quote "it is possible to loan forging power from one account to another without giving up control of the tokens associated with the account. Using a transaction of the account control type, an account owner may temporarily reduce an accounts effective balance to zero, adding it to the effective balance of another account. The targeted accounts forging power is increased until the end of a time period specified by the original account owner, after which the effective balance is returned to the original account." https://wiki.nxtcrypto.org/wiki/Whitepaper:Nxt#Balance_leasingTitle: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: koelen3 on February 28, 2015, 07:13:17 AM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting 51% attack means To own the 51% of hashing power over all not 51% of btc the whole point is to consider this this if Bitcoin switched to Proof of Stake (POS)... so not about hashing power...but the number of units my curiosity is what people think the cost of buying the coins would be if it was POS Okay so even if you're considering it to go PoS , it is quite good but will need 51% of Staking hash Though i would like to know this too , what could happen and how ? Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 07:16:34 AM I think you need at least $1 trillion to buy 51% of all bitcoin I'm sure bitcoin price could rise up to $1 million if you do that ;D But, bitcoin will fail if it going to PoS I hope you voted <$5 billion in that case... since you think POS will kill bitcoin Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 07:19:49 AM A friend of mine suggested that the gov't (or some evil attacking entity) would ANNOUNCE their plans publicly to buy 51% of the POS Bitcoins
Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: virtapayseller666 on February 28, 2015, 07:21:03 AM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting 51% attack means To own the 51% of hashing power over all not 51% of btc 51% hashing power its very large bitcoin network is very large so need so manny bitcoins this will rise bitcoins price if you bought Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: LiteCoinGuy on February 28, 2015, 07:29:01 AM https://www.youtube.com/watch?v=bi2thGzzNSs
Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: happygeorge on February 28, 2015, 07:41:37 AM https://www.youtube.com/watch?v=bi2thGzzNSs This video talks about the "old" bitcoin that is POW... this thread is on the "what if..." on a new bitcoin that were to become Proof of Stake Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: Lauda on February 28, 2015, 08:49:52 AM You have it wrong. You don't need 51% of the total coins to do the attack. You just need 51% of the total staking coins to do the attack(which is much lower than 51% of the total coins). I did not realize this, thank you for telling me. Well then PoS seems even more vulnerable to me.Thats why PoS is not as secure as PoW. Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: BitmoreCoin on February 28, 2015, 11:24:17 AM The more you buy, the more expensive the coin will be. So it could cost you $10m*7m to buy up 51% of existing btc. However, if somebody owns 51% of btc, it could be worthless then.
Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: franky1 on February 28, 2015, 01:31:43 PM OP ill sell you my:
1st bitcoin for $250 2nd bitcoin for $255 3rd bitcoin for $260 .... ..... ...... 3000th bitcoin for $15000 if everyone else done the same .. well your thinking billions$ -> trillions$ just to get 7m coins Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: redsn0w on February 28, 2015, 01:35:17 PM If bitcoin change to a PoS algorithm then it is not more "bitcoin" , because the real bitcoin is based to a PoW algorithm. However I think "> $1 trillion".
Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: DannyHamilton on February 28, 2015, 01:43:54 PM I don't know much about POS, but my understanding was that the problem is that you don't need to own ANY of the coins that currently exist at all. You just need to own 50% of the coins that existed at some point in time in the past.
So, I could spend some of my unspent outputs, and then I could sell (or give) those useless (worthless) now spent outputs to someone else. If they can manage to collect up >50% of the outputs that were unspent at that point in time (even if they've all been spent since then), then they can mount an attack. Perhaps my understanding is flawed? This is where I thought the biggest vulnerability was. Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: LiteCoinGuy on February 28, 2015, 01:49:54 PM https://www.youtube.com/watch?v=bi2thGzzNSs This video talks about the "old" bitcoin that is POW... this thread is on the "what if..." on a new bitcoin that were to become Proof of Stake ah okay, i thought it was the same old story again :D Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: inBitweTrust on February 28, 2015, 01:53:44 PM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. Your question is based upon a false assumption that a 51% attack on a PoS coin requires one to purchase 51% of coins. Certain variations of PoS have already been successfully attacked with only 5% stake - https://bitcointalk.org/index.php?topic=897493.0, and more sophisticated variants of PoS likely need around 25% stake. This stake doesn't need to be purchased either but could be temporarily leased, held by an early stakeholder, or come from a compromised large stakeholder. With PoW there are physical considerations and expenses that often need to be met before performing a 51% attack which raises the security of bitcoin. This being said, I like TaPoS and would like it added as a PoW/TapoS sidechain or as a security layer within a wallet ontop of PoW for bitcoin. We should be considering ideas to make bitcoin more secure and not less secure just in the name of cutting down on an electric bill. Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: koelen3 on February 28, 2015, 03:43:23 PM If Bitcoin were to go the Proof of Stake option (using sidechains perhaps), one of the problem people have with the idea is that it will become much less secure because it would be very cheap to perform a 51% attack. Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now. How much would it cost to buy 51% of BTC (not including lost/unused/unallocated) Please comment below. The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting 51% attack means To own the 51% of hashing power over all not 51% of btc 51% hashing power its very large bitcoin network is very large so need so manny bitcoins this will rise bitcoins price if you bought You realise that will cost 1.8 trillion USD to get 51% of the coin And yes sure! if someone buys it and keeps it just for staking , that will increase it's price so much , becausethat will mean less circulation of coins and thus a big rise in price Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: koelen3 on March 01, 2015, 03:36:28 AM Definitely >1trillion, probably >10 trillion. Once they bought the first 5% of coins, everyone would know somebody was trying to get a 51% stake and would either refuse to sell or hold out for much higher price. Maybe they could try to do it slowly over time to keep people from noticing. Then the question becomes not how much would it cost but how long would it take. A year? 5 years? Not that long If some have 2 trillion He could do it easily within a month Buying off exchanges and places in different wallets Using proxies and VPN's to cover up his shit! Title: Re: Cost of buying 51% of BTC (for attack if bitcoin were to go PoS) Post by: jonald_fyookball on March 01, 2015, 06:32:51 AM I don't know much about POS, but my understanding was that the problem is that you don't need to own ANY of the coins that currently exist at all. You just need to own 50% of the coins that existed at some point in time in the past. So, I could spend some of my unspent outputs, and then I could sell (or give) those useless (worthless) now spent outputs to someone else. If they can manage to collect up >50% of the outputs that were unspent at that point in time (even if they've all been spent since then), then they can mount an attack. Perhaps my understanding is flawed? This is where I thought the biggest vulnerability was. That is generally correct to my understanding as well. Many POS security schemes limit how many blocks deep you can do a reorg, so the "at some point in the past" is limited to a somewhat recent past, but the issue still remains. A person can keep buying coins and selling them, and trying to attack after selling them, so there is essential no cost to the attack, and as such has been dubbed the 'nothing at stake' issue. The higher cost of a 51% attack by PoS is an enticing goal, but I don't think anyone has been able to show how to achieve that while addressing the other security concerns. A hybrid PoW/PoS system also sounds like a good idea, but each such variation has it's own challenges and drawbacks. |