Do you REALLY understand Bitcoin 51% Attack? Programmer explains.

Watch live: ivanontech.com/live

[@omnichron3374]

If you have 51% of the hashing power, dont you already have a house and a car? Hash power is expensive.

[@rootycrypto7655]

I believe he said THEORETICALLY speaking!

[@broski2399]

What if you also want that yacht?

[@scottbuszard]

Exactly, it is easier (more cost-effective) to play the game and get paid to mine honestly, than to subvert the blockchain.

[@polopunk7003]

Billions of people trapped into financial slavery in the debt based fiat system is worth ahellava lot more money than dozens of houses, cars or yachts.

[@scottbuszard]

Watch your language there mate. Manners maketh Man.

[@jimwilde]

Thanks for the explanation Ivan. P.S. I noticed your lighting is using at least 51% of the national grid power.

[@IvanOnTech]

Haha!

[@JohnLocke87]

I was just looking for info on this and the video popped up! Awesome Ivan, thanks!

[@chavdarmihaylov5941]

Great video, Ivan. You cannot see why would someone want to crash bitcoin today. But still you need just 2 conditions for this to happen. First, you need someone or a group of people able to get 51% of the hash power. Second, you need economical logic for someone to crash Bitcoin. 1. Lets review the industry. The barriers to entry the Bitcoin Mining Industry are getting higher and regular people are already not mining. Which means you can easily have a cartel in a few years (Chinese miners for example, who have ASICs developed for them and have independent and cheap energy sources might cooperate). 2. In just a few weeks from now we are going to see futures and options trading on CBOE (Chicago Board Options Exchange) and CME (Chicago Mercantile Exchange). So, if in 2020 you are able to buy a put option for Bitcoin (that's the option to sell a certain asset at a certain price), you can easily find economic logic for someone to crash Bitcoin. The same way some people and organizations have made a killing betting on the financial meltdown in 2008. Not hard to imagine at the time the price of Bitcoin might be $100,000 or even greater. After all, we are lucky to have tech guys warning us on the possible traps. Thanks a lot.

[@kvanw4241]

Thank you for a very good explanation of this 51% attack possebility! It prooves again that decentralisation of miners is vital.

[@pietervanhooydonck5903]

You're doing so well on using the opportunities you get to the fullest. Keep it going!

[@Brix_Creative]

Goodness grace I felt so lucky finding your channel. Very very informative !!

[@alexanderesslinger4971]

If bitcoin derivatives are traded, a 51% attack on bitcoin together with simultaneously short-selling bitcoin could of course be very profitable

[@MauriceLacerda0]

Hey Ivan, what's up? Best explanation of the 51% attack I heard (or read) so far! Thank you for that! I have a question though: as the cryptocurrency market gets more popular, and more and more coins appear, doesn't the 51% attack becomes more likely on "smaller" coins? I mean, getting 51% of BTC hashing power today would be an herculean (and virtually impractical) task to accomplish. But what about 51% of, say, ZenCash, or Faircoin? Since there aren't as many people mining thoses coins, isn't it easier for one node to accquire the network absolute majority? Yours is a great channel and I wish you all success!

[@mf0x222]

Hi Ivan, thanks for the video; keep up the work! Just one question regarding the double spending when having >50% of hashing power: You said that network would choose you privately mined blockchain once it’s longer than the publicly mined blockchain. This means that the publicly mined blockchain would be abandoned by the network. Doesn’t this mean that all transactions that where saved on the abandoned publicly mined blockchain will need to be reprocessed (unless they are already included in your privately mined blockchain). That would mean that eventually your transactions would show up again in the new blockchain which means double spending is not possible??

[@esrayeniaras9292]

Best explanation of %51 double spending attack ever! Excellent. Thanks a lot!

[@danielvega3363]

"It's not profitable to crash the network"... It's not about the money, It's about sending a message

[@CryptoNewsTV]

Seem's like governments only options will be to control 51% of the hashing power to control the money flow they cling to and love to much. Great to know. Will keep an eye on the pool for bitcoin and pray that ant pool gets smaller ...

[@Yewbzee]

Crypto News my thoughts exactly

[@stasyszy]

TANGLE

[@luckerooni7628]

Chinese anti-establishment controls almost a majority the mining and also make many of the most powerful mining products. Rothschild and their like have no skin in this game nor a way to throw money at a shortcut that doesn't pay the people they are trying to overturn and enable them to just purchase yet more powerful technology and then respond by controlling the market of mining equipment.

[@Jordan-Ramses]

Its totally obvious if you understand how bitcoin works. Its a majority rule system. If you can control a majority of the network you can make bitcoins out of thin air.

[@r3d0c]

stop smoking crack Skyler

[@simaogoncalves1957]

Great explanation Ivan. I suggest in videos like this to prepare a little animation. I think it could be a lot easier to understand. Cheers

[@user-oj7ss4up1t]

Ivan great video. Love how you get to the point much quicker now. Great work. Keep it up mate!

[@Flavius-Tech]

There is 2 easy ways how the gov's can stop bitcoin. 1) bitcoin works on a specific port and specific protocol, internet providers can block those protocols in their nodes. So a simple stop is to impose isp's to block ports. 2) is to change online servers time clocks, today is only few servers that serve as clock over the world, including microsoft and linux systems are syncronized by those servers :) , if they want they can easily shutdown those servers and all online computers will be desyncronized :).

[@blackagentsmith3562]

What are your thoughts on tails and the onion network

[@TheSweetswed]

If Cryptos disrupt current Fiat currencies Why is that not enough of an incentive ??? People stop paying taxes trying to hide everything in Crypto and that for me sound like an incentive. Crypto starts messing with the USD and that sounds like enough of a reason to do this

[@DamianGodos]

Hi Ivan, Although you are my guru I've got to correct you because you chose a bit unfavorable wording. 51% of computing power doesn't mean that you will automatically win the competition and that you immediately outperform all other miners. It only means that your PROBABILITY of finding the nonce hence to mine next block is higher! That's how the proof of work algorithm works - based on probability. Best Damian.

[@IvanOnTech]

Yes good detail, however constantly having a higher probability over time will practically mean that you win the competition in building the longest chain :)

[@DamianGodos]

Well, not really. In the long term you will mine more blocks in total but in the short term you will loose about 50% of the 'battles' (51% to 49% is not much of a difference) which makes tampering with the blockchain i.e. creating longer chain difficult...

[@IvanOnTech]

The attacker privately mines their own chain and then publishes that chain reversing transactions that are not included in that new chain, so it's not about winning the "battle" for each block in my view but the overall ability to create the longest chain by having more power

[@pfcwells522]

Don't for get that when the other miners start noticing that 51%er none keep popping up. They will start dropping from that network. Making the pool smaller and giving the 51%er more changes to validate more blocks. Which goes to Ivan's point.

[@banzobeans]

Is there no way on the protocol layer to instead drop the source of the 51% attack?

[@ZakionBitcoin]

Hi Ivan, it's been a while since you talked about the 51% attack, what is your take on the current mining pools having few holding more than 70% of the hash power?

[@doorknobfart]

My understanding of blockchains is still very limited so correct me if im wrong, but the mining power required to consistently pull off a 51% attack would actually require a lot more than 51% control of the network, especially if you are trying to tamper with blocks further back in the chain. This is because with each edit, the hash of the block will change and you will need to rediscover the hash with the proper nonce value. If there are 10 blocks ahead of the one you edited, you will then need to do this for each subsequent block until you catch up to the current block. To consistently do this would require much more than 51% control because you are trying to beat out the rest of the network, which has about the same odds as you to solve blocks. (51% vs 49%).

[@akita5580]

No, 51% really is enough. The easiest way to perform double spending is to spend the first time after having started to compute unbroadcasted blocks. But if you want to "change history" before you start to compute, it will only take longer. For example, if you want to change a block 10-block ago, with a 51/49 ratio, it will take you 245 blocks to catch up, so about 2 days. Not bad if you ask me.

[@garyshaw8449]

isn't there a time limit also like 10 minutes?

[@menacetohighsociety]

Which is why the electrical cost of generating that much hashing power is an important deterrent to put off would-be attackers.

[@ethercept]

Ivan, thank-you for this video, I tried to explain a 51% attack the other day and failed miserably, just emailed this to those two Devs.

[@NixonRexzile-xz4sq]

you know he's wrong and it's completly impossible to compete with miners and consumers!

[@jonashapp3867]

Great explaination! I thought I kind of knew how it works but you told be better :D Greetings from Germany

[@soldadopreciso]

hello pal greetings from Ecuador, thanks for the video, explanation begin at 1:25

[@Jeryboulet]

Great video, I was hoping that you would talk about the lost in confidence. People often think that an attack would means that they lose their bitcoins, while actually bitcoin would likely loses its value (which could have the same result in the end!).

[@stuarthayward4756]

Best technical crypto commentary by a long shot, the only people that truly understand investment prospects are programmers. Keep up the good work Ivan ! Please publish a video on Stratis if you are able.

[@JohnDoe-kg4zn]

So basically what your saying is that the cost of destroying bitcoin is within the budget of any major nation?

[@TheSirkarl101]

There are calculations on this exact attack. It calculates 1, 006,247,972 dollars per day in equipment and power to perform such an attack. I have no idea how accurate these numbers are but that is what I have been able to find. Found interesting. I found another calculation that puts such an attack at over 4 billion dollars. Hell Jeff Bezos could perform himself given time to accumulate the over 40k S9 mining rigs etc....

[@JohnDoe-kg4zn]

Thank you for sharing that

[@TheSirkarl101]

yes, yes, yes!!!!

[@JohnDoe-kg4zn]

What are your thoughts on the assertions that Bitfinex and Tether are manipulating the bitcoin market cap through issuing non-USD backed Tethers which are then sold for BTC?

[@CheeseChuckie]

Jeff Bezos owns AWS... he could do it right now. He owns the most computing power of any organization on the planet, by a mile. I think 95% of the internet is powered by AWS today.

[@archhangell]

Welcome back to Cold and Dark timings of the day :)

[@sudd0]

Great to know! Can you please next time compare this to Tangle or some other cryptocurrencies to mention these possible/unpossible risks? I think this will be helpful to know for many people including me, thumbs up. I am so happy that you make these videos about technical side of cryptocurrencies, for me and also many other people its very helpful to understand cryptocurrencies, hope you will continue, you make awesome knowledge for people 👍🏻👍🏻👍🏻

[@Bitcoin_not_crypto]

Thanks for a good explanation. This further supports my belief that running our own Full Node to verify our txs is essential for security and the well being of the network.

[@P-nutBD]

Dude, this is something that I had figured a while back but thought of it as extremely hard to do. Glad there's others like me.

[@NUFCMVFC]

Thanks for explaining. Makes one wonders about the implications of "arbitrage" perhaps under certain circumstances or Miners to act akin to Fed Primary Dealers and influence the inflation rate, eg hold and then dump heaps of BTC at once impacting its Purchasing power etc...

[@georgechristou7982]

well explained. thanks Ivan. keep making these videos man!

[@jos705]

what if 51% of the mining power is owned by different companies, but these companies are from the same owner without anybody knowing it?

[@muhamyakbar7363]

Hi Ivan, really happy watching your videos, it means a lot for me and my friends who start creating research team since the beginning of this year, we'd be happy if you can come to Indonesia and speaking about blockchain. do you have a plan to visit Indonesia ?

[@izio4408]

Well since bitcoin is a public ledger, you would be able to trackdown whoever did this 51% attack. And that person would be put in jail. But also this is just a ridiculous feat that would never happen.

[@mathiasvangenabet368]

First of, love your videos Ivan, they've been more than helpfull. However, I don't quite understand what happens to unconfirmed transactions. They're going back into to 'unconfirmed pool' I guess? But what if the 'double spending' transaction gets confirmed and the original goes back into the unconfirmed pool?

[@hebraist]

Awesome! Love this! Thanks man. Where are you from and how old are you? You look around 28? Maybe 32?

[@niclandstrom3516]

Thank you for spreading the knowledge!

[@ZIINOMUSIC]

great info as always :)

[@spamp2179]

@Ivan on Tech Why would there be different length chains? Can you please elaborate and provide and example? Thank you great video!

[@lenishe]

Great video! Thanks, Ivan

[@emilsajatovic9197]

Hey Ivan, since i couldn't find any decent comparison and you do great content, could you make a video comparing Blockchain PoW/PoS vs Tangle for non "technical" people like me :) i think that would be awesome video!

[@subrotoxing8214]

thank you for taking the time to explain it's great info ^^

[@banzobeans]

Thanks for your explanation. As for your double-spend example: Do I understand correctly that after having bought my house or car in the original public chain and then announcing my privately-mined version to the public, those first transactions would be annulled? So the sellers of those original assets (house/car) would notice this and context. i.e. they wouldn't let me have my car or house? => So this attack can only work for things that can very quickly change hands in a way that can't be undone. It seems a car or a house are not such good examples?

[@hanstausend9922]

Hi Ivan, great video but there are 2 things I havent quite understood yet. 1. Wouldnt it be obvious that someone commited a 51% attack because once he releases the longer chain the notes could see that an usual high amount (lets say 10) of blocks were verfied by the same Miner in the row giving himself also all the coinbase transactions to his adress? 2. Is it correct that the 51% attacker may doubke spend or exclude all transactions to a certain adress BUT would not be able to transfer money to himself because he doesnt own other Note's private Keys. Hence all these transactions would be detected a froud immeditely by other Notes because they cant use the public keys to decrypt the transactions when checking them?

[@swedishmanguy]

Yes, Ivan did not point out the reality that you just did. Also, the longer chain goes back to the genesis block of the bitcoin blockchain which is longer than an attempted 51% attack would have. Therefore, there cannot be a successful attack. Therefore, a 51% attack is a myth because it's not possible with all the nodes protecting the blockchain.

[@alastairlocke4621]

You can make as many wallets as you like!

[@karimi1367]

Ivan If that happens, does the community notice it right away? for example in the double spending, does the sender and the receiver have the bitcoins in their wallet or is it just the sender that has it?

[@nataliapritt3641]

Question, from your explanation, I still don't get why must it be 51%? If it's a matter of competition and being the fastest, then isn't the fastest miner can do double spend attack regardless of the percentage of the hashing power? For example, if there are 3 miners each with 33%, 33%, and 34% hash power. All of them would create their own version of the truths, and theoretically, the 34% can outpace the rest and do the double spend attack as well, am I right?

[@manfredexz5197]

I have the same question, did you figure it out?

[@willglynn1231]

the two 33% won't act against each other based on game theory

[@generalaone]

You are right it's just an unlikely scenario. And it could backfire. For instance if the 34% starts manipulating the network, both the 33% miners are in 0 control of the network. It would make more sense for them to team up and they now control 50% of the network each because their combined hashing power of 66% beats 34%. The 34% miner now has 0 control and unless he can 51% attack them both he has to join them because he will control 0% of the network. Did that make sense? And after he joins them his presence turns their 50% shared ownership of the network back to 33% and we're back where we started.

[@cryptobirddog334]

I agree the potential profitability of the digital currency markets will be more attractive than the sabotage project of 51% ~ Good Vid Ivan, Thanks!

[@MerlinMason]

Except if you can short bitcoin in a futures market 😬

[@simonlock846]

A question, Ivan. If you spent your BTC on the public chain and then announced a longer chain without your transaction excluded, would your transaction not just go back in to the pool of pending transactions? To pull this off would you not need to create a conflicting transaction from your address so that your original transaction will be rejected next time around as a double spend? Thanks for another great video!

[@gavingonzalez7174]

Yeah, had the same question lol

[@deathsalesman8462]

Great explanation!

[@MawaMaverick]

@Ivan on Tech. You sound Kazakhstani. Are you from there?

[@michaelleon9436]

Very interesting. Would people that have downloaded the entire ledger be able to see that the bitcoins coins that the 51% attack have spent twice, will they be able to know that there are more bitcoins then should have been created.

[@benrim7466]

with futures starting Dec. 18 , a large hedge fund would have the incentive from shorting the futures to pull off this attack because even if bitcoin burns he can profit from the futures, what is your opinion about this risk ? is ETH or any other crypto immune to 51% attack ?

[@quietackshon]

The 51% problem was a concern in the early days of BTC, but now it's not very likely, I won't say impossible, but improbable. Also, 3/4 of BTC has already been mined.

[@exploredreamdiscover2591]

Thank you for explaining this and all of your videos! I hope one day to be able to meet you at one of the conferences. Here's a crazy idea, let's ban all private companies and governments from buying coin. Keep it free.

[@alanlanzoni8854]

Great video. Congrats.

[@al-jabalaudiovisualproject4828]

Hello Ivan, First of all thank you, sir, for sharing your valuable knowledge in such a fair and professional manner. Can you please elaborate on the likelihood of a 51 percent attack, and how much it would cost a malicious entity to activate it? Because I mean even if it costs several hundred billion, it would still be considered peanuts for governments and central banks to do away with bitcoin once and for all.

[@boring-username]

This is a really great video. I've been trying to read all about this, but you explained it in one go. I do have a follow-up question, however. So what would the attacker be adding in their private blockchain? Are these the same blocks that the other miners with less computing power are ALSO trying to solve, you just happen to be the one getting them since you have all the power? I think I'm mixing up the term "private" with "illegitimate". If I understand, this is actually just private because you are adding the latest blocks to the chain, but you just aren't announcing them. So these blocks you are privately mining can include legitimate transactions happening in the Bitcoin network, correct? Thank you again.

[@monicasmith936]

Great video. Thank you!

[@JohnDoe-kg4zn]

What are your thoughts on the assertions that Tether is being used to pump up the bitcoin market cap?

[@maartenkaspersma]

Hi Ivan, I would love to hear your opinion about what happens when the block reward incentive for miners goes away when the maximum amount of bitcoins have been mined. Will they switch their mining to other currencies causing bitcoin to collapse? I find it hard to believe that transaction fees would keep the miners aboard.

[@stevenjohnston5737]

What about owning 51% of nodes? How would this change the equation?

[@ThomasHaberkorn]

Truth is provided by an arms race of computation power.. Do not let one become too powerful

[@michelefacchini7764]

in case of a 51% attack to roll back a chain, chain could be rolled back at any event/moment in the past , or the attack should last as the time passed from the event that should be reverted till the start of the attack??? @Ivan on Tech

[@TheKarantan]

Really good explanation of the 51% attack. Although I don't agree that if you have 51% of the mining power you would always mine the next block (and always receive the reward). You would have 51% of the chance of mining the next block and not 100%.

[@pawel82x]

karantan but in long period of time 51 will increase because many other miners will quit bacause they will mine very rarely and electric bill will eat all profit. 1% looks small but in statistcs it is everything. Lok at rulette game the adventage of casino is similar and in long period of time they get all money

[@TheKarantan]

True but 1% is still not 100% no matter how you look at it :)

[@Ekitchi0]

All you have to do is keep your blocks private until your chain is longer and then release it. You will have 100% of the blocks on that part. Then do it again, wait a couple of blocks and win the race again. That's how with 51% of the hash power you can get 100% of the mining rewards.

[@CristianoRonaldo272]

Great explanation

[@i8aNooB]

So how do we know Bitmain aren't doing this on the bcash network?

[@mamunhasan5242]

Great Explanation. Is it possible to run a modified version of Bitcoin node which will always generate less complex puzzle for the Block so that someone can mine 51% faster than others with small computation power?

[@davidselovin6053]

Photographer's friendly advice: position you lightsource a little bit further from yourself (inverse square law), so that the contrast between the lighting levels on your face and environment go down, it will look much better. ...or you could just put some diffusers (eaven papper tissues would do) over it....

[@Cryptokane-xm5mw]

thanks for explaining this attack now I understand how it works and puts me at ease because you are right this would not be a wise attack to try and do. thanks

[@letsfixit1594]

So would that mean the coins would be taken from the wallets where you had sent them to buy all the stuff?

[@taopaille-paille4992]

Very clear and good explanation

[@pveentjer]

Good explanation.

[@galbak9445]

hey ivan and hat will happend to the transaction you made for the housh? the bitcoin will stay in the seller account or they will disapear?

[@traiancoza5214]

Very well explained, thank you.

[@ithound]

perfect explanation!

[@theflipside2709]

Again, very helpful!

[@rpals5412]

Hey Ivan. Great video. just wondering about a scenario. What if 99 people are the only miners, and 98 of them mines with 1h/s and the last person mines with 2h/s (100h/s total). Will that one person, who has the fastest miner also be able to execute these attacks? In that case, why are the biggest mining pools not performing these attack all the time?

[@PedroRodriguez-ip2gs]

Hey Ivan , I was watching one of your videos from back in the day, and I have a serious question About the “Shadow Mining” or Bitcoin Blockchain Reorganization If somebody created a longer blockchain, with different block/transactions in each block, then passed them on to the full nodes, that, following the longest chain Rule, would accept this new “erroneous Block chain” as valid, and drop the “Real” Blockchain, wouldn’t all transactions, contained in the dropped blockchain, return to the mempool to be added to new blocks again? As in when we have an orphaned block? So one day or another, the transactions that a malicious person/miner kept out of that new block chain, would be added again to a new block, no?

[@jdylan637]

There is one man that would do this his name is SORO!

[@Peace-nz3jx]

Stop is dead . Maybe the GOV

[@jdylan637]

George Soros!

[@iexist6021]

Bigger. The IMF.

[@theGADGETSplaylist]

The best explanation on this vulnerability.

[@DoubleBassX2]

Can we force the discovery of new blocks as soon as they are mined? (Blocks found instantly/publicly update network or something?)

[@lm07jem96]

Great explanation - so, how can the network be protected from the 51% to prevent this?

[@IvanOnTech]

good question! will cover in a later video!

[@lm07jem96]

Look forward to that. Thanks, Ivan - great content!

[@RandomNoob]

It cannot it's up to the users and miners to protect it for example back around 2013 there was a huge pool that was gaining a huge share so they shut off new users so they could not gain over 50% now people don't seem to care. It in theory can be executed on say the Bitcoin Cash network by any unknown mining group because they have a much smaller amount of hashing power so much easier to exploit but with bitcoin having so much it's much less likely to happen

[@worldzztv7710]

The more miners out there the harder it becomes to gain the 51% of hashing power.

[@scottbuszard]

The goal is to have at least 3 major miners who are at a constant state of war with each other. Equilateral distribution creating balance and no clear dominant miner.

[@walterormsby4931]

Thanks for your explanation, 51% hashing power makes BTC less decentralised? If someone can control it like that?

[@TheSirkarl101]

What would it cost approximately to perform a 51% attack? So if me and my wealthy friends were to buy the equipment and set up, then short Bitcoin on Chicago mercantile how much would we profit while killing Bitcoin in the process? This now is going through my mind anyways if I had any money to speak of! So maybe having Bitcoin traded on markets is not such a good thing after all hum? Sorry Ivan but this video indeed left me confused and now worried that institutions and central authorities will have the means to kill Bitcoin and until you tell me otherwise profit in the process...Love to see a follow up video explaining why it will not happen!

[@FourOneNineOneFourOne]

Would cost around $6.000.000.000 - $10.000.000.000. And you'd be able to do it once. So it's hard to imagine what can you buy for 10$B+ keeping your anonymity, without crashing the market, in a stealthy way, because the rig will be useless after that. Most people agree that 51% attack is not practical anymore.

[@NHKxt]

your LED lighting is really screwing with your auto-white balance lol

[@barrietremans219]

Great stuff Ivan! Thank you for thorough breakdown of the issue. let's Not allow Government to mine! :)

[@cyleyoakum9449]

Ivan is going places guys. He's gonna be a big key figure in this new crypto world.

[@enyx6754]

what does he mean by private mining? thought you couldnt do it offline?

[@wbltrack07]

Great video Ivan. So why do they allow miners to mine in secret and then notify the network at a later date? Wouldn't requiring them to immediately report that they are working on new blocks massively help to prevent such attacks?

[@gtbsaraiva]

When all the other miners receive a blockchain for example 10 blocks longer and diferent from the previous they were validating they will realize that theres something illegit. At this moment there will be a fork on the network. Other way to realize that theres something abnormal is the sudden increase in the hashrate of the network or the longest chains coming often from the same place

[@Ofirsen]

I like how your pic in the corner says 45k ! Nice growth, mb update it at 100 😀

[@hussamkhatib746]

But will there even be a conflict in the first place to consider the longest chain? consider the hacker changes a block in the chain , and hashes all the following blocks and has the longest chain now. But the conflict shouldn't arise because the hacker's validated hash is different than the general ledger /basically everyone else. So the hacker's should be cut out , because his hash values don't match with majority of the world.

[@script4724]

In this case hacker has majority of the computing power in the world - 51%

[@DanielDerDenis]

Thank you for this video. There are a few flaws in your explanation but you final result/conclusion is definitely right: A 51% is ultimately prevented by simple economics (destroying value of your coins). The biggest and very important flaw in your explanation is, that with 51% mining power you DO NOT get All the blocks! With 51% hashing power, the chance THAT YOU GET ALL BLOCKS is statisticaly at exactly 51%!!! that means that over 1000 blocks, you will probably mine 510 blocks. The rest of 490 blocks WILL PROBABLY STILL BE MINDESTENS BY OTHERS! That also means, that the chance that you buy your house and your double spend is successful is only at 51%! So if you do that with 100 houses, you will probably only be successful with 51 of those houses. And while you do that, people and the network would probably start to realize what you are doing and the value of Bitcoin/BitcoinCash would immediately drop tremendously. That would make everything next house, on the way to 100, more expensive. So if the others power up und you loose your 51% status and prices go up again, the 49% of house sellers who received your coins will probably have received round about double the amount of Bitcoin/BitcoinCash as they would have without your attack. So if you loose your 51% status, prices will normalize, ~half of the house sellers will have received nothing and the other ~half will have received double the amount. Which means: the attacker spend the same amount of money and has no gain. = attack has no economical benefits. Additionally, when you have 51%, the other miners all have still 49% of the blocks and therefor still receive 49% of the Block rewards. So every single miner is always competing with THE WHOLE REST of the network. If he has 10% hashing power. He will on average mine 10% of the blocks and will also get 10% of all the block rewards. At the same time he will only have paid 10% of all the electricity cost of the network. How/If the other 90% are divided doesn't matter for this miner at all. He will never be put out of work because of that. That's the beauty of the Bitcoin concept, it is soo genius because it takes just everything into account :) So ultimately this attack is in no means a success. TL;DR: The explanation is flawed and underestimates the prevention mechanism of the original Bitcoin concept. 51% attack to doublespend is already prevented by immediate economic effects --And therfore still: Your conclusion is absolutely right!

[@psawmora]

I am finding it hard to understand how a completely new chain gets announced. Could you please explain the logic involved in accepting a block by a node ?

[@joaosousapinto3614]

Very good video! Most discussions on this topic are super wishy washy, and don't concretize exactly what one can and cannot do with 51% attacks.

[@gp3631]

thank you for talking with a fast pace. Annoying setting all my videos to 1.25x lol.

[@pfcwells522]

I already understood what it was. I think it was a pretty good break down for the newer folks. Keep up the good work.

[@polopunk7003]

PfC Wells congratulations what a worthwhile comment to share 👻

[@pfcwells522]

Polopunk lol to the ghost.

[@daytradingpsychology]

How long would it take for a 51% actor to have the longest chain? Thx.

[@kckong3]

Is there & what is the official response to these scenarios? If the transactions (1st round spending on house car etc) are excluded, surely the seller's wallet will be short - wouldn't he raise a ruckus? UNLESS, you're saying that his wallet will be credited but the perpetrator's won't be debited... in which case the total amount of bitcoins in circulation will have increased by the amount of that 1st round spending. Is there any check on the total amount of bitcoins in circulation ?