How long does it take to go from 51% hash power to 100% hash power?

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Once an attacker has acquired 51% hash power, is it possible to quickly get to 100% hash power by simply refusing to build on blocks created by other mining nodes and therefore discouraging mining entirely?

If 51% guarantees 100%, how quickly can this transition (from majority to total control) be expected to occur?

Manish

Posted 2013-04-19T14:20:09.973

Reputation: 1 972

Answers

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From What can an attacker with 51% of hash power do?

Prevent some or all other generators from getting any generations

So, yes. However, it doesn't immediately give him more mining income. Once the block readjustment happens two to six weeks or so after the attack, the bitcoin network will notice that far fewer blocks were made, and the difficulty will go down.

Nick ODell

Posted 2013-04-19T14:20:09.973

Reputation: 26 536

If I understand your answer correctly, you're saying that the only way to tell when it's no longer worth trying to mine any more coins is to look at the new adjusted difficulty level. Is that right? I was thinking more like if you're generating valid blocks and they're still getting rejected then maybe it's time to quit mining. But how long would it take for the rest of the 49% to notice this? I mean, is there a formula?Manish 2013-04-20T19:38:58.753

Also, what if it's not an external attack but rather an internal buyout (i.e. a big company just bought 51% of the hash power)? In this case there's no new hash power added to the network.Manish 2013-04-20T19:43:45.180

@Manish only way to tell when I think a better way would be to look at all of the pool operators now complaining that they're not making any money. Also, what if it's not an external attack but rather an internal buyout Can't be detected purely by looking at the network.Nick ODell 2013-04-20T20:02:57.197

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Remember that one would have to gain over 400 petaflops of processing power to gain 51% of the network. The top ten supercomputers in the world combined aren't even powerful enough:

http://bitcoinwatch.com/

http://www.top500.org/lists/2012/11/

Charles Hoskinson

Posted 2013-04-19T14:20:09.973

Reputation: 969

3Note that flops stands for FLOating Point operations per Second, and is perhaps not the best measure of a mining algorithm that uses no floating point operations.Nick ODell 2013-04-19T19:08:28.087

You and your semantics. I'm just trying to demonstrate that taking the network down via a 51% attack isn't going to happenCharles Hoskinson 2013-04-20T02:37:25.197

@CharlesHoskinson George Soros could just buy out most of the miners. Then what? Anyway, I see your point.Manish 2013-04-20T19:28:59.303

Doing so should greatly increase the value of the bitcoin resulting in more people entering the market to mine. Thus Soro's play failsCharles Hoskinson 2013-04-20T20:09:36.727

This misses the question.Murch 2015-06-09T22:59:09.513