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Sabotaging Bitcoin

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Re: Sabotaging Bitcoin

#181

Post by buzzin__ »

mrb wrote: post #105
free_bip wrote: post #104

Earlier quoted context omitted.

How are you so confident that it will never weaken? Especially since there will come a time when the block reward is literally 0.

Tx fees make up a bigger and bigger fraction of miner rewards over time.

But transaction fees reset to zero on each block. If relying solely on transaction fees, why would you mine if they are zero? So, on the start of each block, miners will shutdown, or perhaps switch to a different currency where it would be profitable to mine. This surely weakens the security of Bitcoin.

Re: Sabotaging Bitcoin

#182

Post by rlpb »

UltraSane wrote: post #75

Bitcoin is the least efficient technology ever created. There is no limit to how much electricity it can consume just to handle 7 transactions per second. No matter HOW much electricity it uses this value will never increase.

There is a limit. The cost of electricity required is bounded by the value of the reward (block reward plus transaction fees). The value of the reward is bounded too, since the "import" of electricity into the Bitcoin economy is inflationary.

Re: Sabotaging Bitcoin

#183

Post by georgefrowny »

emil-lp wrote: post #110
copirate wrote: post #100

Earlier quoted context omitted.

> If a pool can set up a situation where they mine a block and wait X seconds to reveal it, they can force other miners to waste X seconds of has power and gain an advantage. How is it wasted if they work on the current chain? If they find a block during those X seconds, they'll propagate it before the waiting pool does. The waiting pool will then just lose the revenue from the block they put on hold. They're the one…

If you mine a block without revealing it, not only are you the only one that can mine the next block after that, but everyone is mining on the "wrong head". There's of course the risk that someone finds a different head in the meantime, but otherwise, you waste competitors' resources, while you get an advantage on the next block.

What makes it more likely that your first block ends up the next head and you're not wasting your own time on the second one if someone beats you to the first one while you're holding off?

Re: Sabotaging Bitcoin

#184

Post by copirate »

Majromax wrote: post #179
copirate wrote: post #169

Earlier quoted context omitted.

> Except that by withholding their block, they got a headstart so they are more likely to find the second block. So it's not the same. Withholding their block (5s or whatever) doesn't make them more likely to find the second block. The probability of finding a block is always the same, given a hashrate. They are the only ones mining on this particular chain, but that's not an advantage either. How mining on a hidden…

> They are the only ones mining on this particular chain, but that's not an advantage either. How mining on a hidden chain is an advantage? It's easier to see the argument if you have a head start. Imagine you've somehow created a private chain that's 10 blocks ahead of the public chain. You could publish that now and earn 10 blocks of reward, or you could continue mining until the lead diminishes to 0 blocks, earnin…

But to get 10 blocks ahead you have to withhold blocks before knowing you'll be ahead. If you don't get ahead, you'll likely lose the reward of the blocks you withheld.

So, you have to risk a lot of rewards, and for what potential gain? If you win you get to discard some blocks of others. You don't get more rewards, you just make others earn less (and you push the difficulty down a bit).

I can see how you get a chance to double spend, though. If you want to double spend a transaction with N confirmations, you've to be N+1 blocks ahead in your hidden chain, publish your first transaction, wait for N confirmations on the public chain, and you publish your chain that's still 1 block ahead (and includes your double spend transaction).

Indeed, it's not "51% expensive", but it's still very expensive because of the rewards lost during the failed attempts before you get ahead enough. Actually, it might even be more expensive, because with 51% you're guaranteed to get ahead enough at some point, so you don't really risk your rewards (if you can maintain 51%).

Re: Sabotaging Bitcoin

#185

Post by jksmith »

munksbeer wrote: post #154
jksmith wrote: post #85

Earlier quoted context omitted.

Did you read the paper? There exists a technology that has purely enforceable property rights. What is that actually worth? I don't know. Yeah yeah, I've read the arguments about liquidity issues, shutting down the rails, making it illegal to trade, etc. but that's beside the point and depends on a thousand future variables to play out. So I don't know if btc will make it or not, but I do know property rights mean ev…

> So just the ability to have a technology enables pure property rights to a world where nobody really has enforceable property rights over anything seems pretty interesting to me. Bitcoin doesn't enforce property rights. The only thing you own is your bitcoin. The fact that I "own" my house and the land it is built on is enforced by the state with guns.

You're not getting what I'm saying. Before this technology, the concept of property rights could not be defended, depending on the attacker. This tech allows that, even if it is just for one use case.

Re: Sabotaging Bitcoin

#186

Post by jksmith »

nradov wrote: post #86
jksmith wrote: post #85

Earlier quoted context omitted.

Did you read the paper? There exists a technology that has purely enforceable property rights. What is that actually worth? I don't know. Yeah yeah, I've read the arguments about liquidity issues, shutting down the rails, making it illegal to trade, etc. but that's beside the point and depends on a thousand future variables to play out. So I don't know if btc will make it or not, but I do know property rights mean ev…

Property rights are enforced with guns.

So is theft. Depends on who has the most guns.

Re: Sabotaging Bitcoin

#187

Post by palata »

copirate wrote: post #177
adgjlsfhk1 wrote: post #176

Earlier quoted context omitted.

the key to realize is that this strategy only makes sense if you have a considerable fraction of total hashrate. If you have 10% hashrate, delaying for 1 block period gives you a 10% chance of finding another block on top (that no one else can search for because you haven't published the first one).

But by withholding you also increase the risk that your first block will never end up in the main chain (if the remaining 90% find a block while you're withholding). And you would sill have 10% chance of mining another block if you don't withhold. What advantage does withholding give you?

> What advantage does withholding give you?

One last time. By withholding, you have a headstart on the next block. If you can mine for longer, you increase your chances.

Re: Sabotaging Bitcoin

#188

Post by palata »

copirate wrote: post #184
Majromax wrote: post #179

Earlier quoted context omitted.

> They are the only ones mining on this particular chain, but that's not an advantage either. How mining on a hidden chain is an advantage? It's easier to see the argument if you have a head start. Imagine you've somehow created a private chain that's 10 blocks ahead of the public chain. You could publish that now and earn 10 blocks of reward, or you could continue mining until the lead diminishes to 0 blocks, earnin…

But to get 10 blocks ahead you have to withhold blocks before knowing you'll be ahead. If you don't get ahead, you'll likely lose the reward of the blocks you withheld. So, you have to risk a lot of rewards, and for what potential gain? If you win you get to discard some blocks of others. You don't get more rewards, you just make others earn less (and you push the difficulty down a bit). I can see how you get a chanc…

> But to get 10 blocks ahead you have to withhold blocks before knowing you'll be ahead.

You KNOW you are ahead, because you found a block and nobody else has published a block.

Re: Sabotaging Bitcoin

#189

Post by palata »

copirate wrote: post #169
palata wrote: post #165

Earlier quoted context omitted.

> I fail to see how withholding is profitable. Because you keep ignoring the part where it is profitable :-). > If A finds a second block between minute 1 and 2, then they win, but it would be the same if the didn't withhold their block. Except that by withholding their block, they got a headstart so they are more likely to find the second block. So it's not the same. And you keep ignoring the fact that they don't ne…

> Except that by withholding their block, they got a headstart so they are more likely to find the second block. So it's not the same. Withholding their block (5s or whatever) doesn't make them more likely to find the second block. The probability of finding a block is always the same, given a hashrate. They are the only ones mining on this particular chain, but that's not an advantage either. How mining on a hidden…

> The probability of finding a block is always the same, given a hashrate.

I think you are missing something very basic here: the longer you compute, the higher the likelihood that you will find the hash before the others.

The extreme case being that if you can try ALL the possibilities before the others can start, then you are guarantee to find the solution before them.

Re: Sabotaging Bitcoin

#190

Post by basilikum »

palata wrote: post #189
copirate wrote: post #169

Earlier quoted context omitted.

> Except that by withholding their block, they got a headstart so they are more likely to find the second block. So it's not the same. Withholding their block (5s or whatever) doesn't make them more likely to find the second block. The probability of finding a block is always the same, given a hashrate. They are the only ones mining on this particular chain, but that's not an advantage either. How mining on a hidden…

> The probability of finding a block is always the same, given a hashrate. I think you are missing something very basic here: the longer you compute, the higher the likelihood that you will find the hash before the others. The extreme case being that if you can try ALL the possibilities before the others can start, then you are guarantee to find the solution before them.

That's only mathematically true. The advantage is way too small to be relevant.

Your advantage is having exhausted a fraction of the search space. But that fraction is tiny.

You're trying to find a hash with a value below a certain threshold (simplified said, a hash starting with a certain amount of zeroes). You do this by trying random inputs to the hash function. Every input has the same probability of getting an output that is low enough in value. You are not advancing by having tried other inputs. It's practically equivalent to rolling multiple dices until enough of them show a one. Every roll has the same probability of succeeding regardless of the rolls before.

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