Topic: Network Redundancy - page 2. (Read 2962 times)

Oh, why not introduce some incentives to encourage running a full node then? If not, then won't the number of full nodes just continue to decrease as the blockchain grows?

Could you comment on the incentives to maintain full nodes described here: https://en.bitcoin.it/wiki/Proof_of_Stake

I would appreciate more feedback.

You should worry about BFL, not about some supercomputer somewhere. No we are not safe from BFL (unless their claims are complete scams).

this * 1000

No need to speculate about "external capacity" of the attacker. Assuming most of miners are somewhat rational, they have some reasonable expectations for their ROI period. Let's be optimistic and say two years. This amounts to 105,192 blocks mined. With the reward of BTC25 per block, mining investment would not be more than BTC2.6M - currently worth just over USD 31M.

Alternatively, today's typical price of mining power is about 1 USD per Mhash/s. The network total is 25 Thash/s, meaning total investment of at least USD 25M. Add to this the cost of power, and we are even closer to the estimate above. It is safe to say that the total mining investment is somewhere between 10 and 50 million USD. This is the real measure of the security that miners provide, and this is what it takes to stage a >50% disruption.  It is irrelevant if CPUs, GPUs, FPGAs, or ASICs are involved - whatever the best available technology is, it is available to both honest miners and (imaginary) attackers. If bitcoin value goes up, mining investment will increase, and vice versa - it has been shown many times that difficulty follows price (especially when corrected for the technological leaps in terms efficiency). Mining power should be measured in dollars, not hashes per second.

The real question is - what would be the incentive for anyone to spend tens of millions of dollars to temporarily disrupt the network? They could just mine and make money.

The peer-to-peer network is more vulnerable to low level network attack, than the ever-discussed 51% hashing attack.

You can help, by running a full node that accepts incoming connections.

It's pretty much impossible to know what the smallest we could be without an attack being attempted is, but bigger does make coins more valuable all else equal since an attack is less likely. Also there is the other purpose of mining which is to get coins distributed initially, total power doesn't really tell you that but I would think that high power correlates with more miners to some extent.

Is the bitcoin network dangerously under powered and on the verge of being subjected to a 51% attack?

Or is it overly redundant and could afford to have the hash rate drop to a fraction of it current value and still be secure?

My instincts tell me we are safe, but where are the numbers?

Hash rate alone doesn't help us because we do not know the potential hash rate of an attacker to compare it to. The problem is determining the greatest amount of processing power that is in the hands of one single external entity.

Currently, although I may be wrong, the most powerful computational machine external to bitcoin and controlled by a single entity is the Livermore’s Sequoia supercomputer at Lawrence Livermore National Laboratory which puts out 10.5 petaFLOPS.

According to BitcoinWatch, the equivalent rate of petaFLOPS for the bitcoin network is 307.94. Now I know your going to moan about comparing flops and hashes but we have no choice here.
 
If we stipulate that the computational power wielded by the largest know potential attacker is always equal to a redundancy of 1, then we can say the bitcoin network currently has redundancy of just over 29.

redundancy = bitcoin capacity / max know external capacity
29.32 = 307.94 / 10.5

Or to put it another way, an attacker would require more than 29 times the processing power than that know to be controlled by a single external entity in order to have more than 50% of the network processing power.

Although this gauge is not perfect, as it ignores unknown entity's and pools, it does at lest provide a benchmark.

Thoughts?