141–150 of 289 posts
Given enough time, chains behind the lead position will always succumb to this attack vector. Ethereum's design was flawed in other ways, but at least now it's clearly best used as the sandbox that it is.
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Imagine all the Bitcoin miners out there right now using their ASICs to do extremely efficient hashing in the hopes of generating a block reward. Let's didactically suppose there are 100 such miners total. Now imagine Dinkycoin comes along and releases their cryptocurrency that uses the same hashing mechanism for the block reward. Initially they have the block difficulty level pretty low as there aren't that many peo…
But if they throw hashpower on Dinkycoin, wouldn't Dinkycoin's difficulty increase? If the difficulty for Dinkycoin re-targets more aggressively, then Dinkycoin would quickly gain more security in the process!
dPoW explained here. https://blog.komodoplatform.com/delayed-proof-of-work-explai...
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It's worth pointing out that just getting 51% hash rate isn't enough to steal money. It's really just the entry point at which you _might_ be able to steal money. To actually steal money you need to falsify at least six blocks, which in turn means you need to mine six blocks in a row (roughly speaking). The probability of this being successful is (1.0-0.51)^6 - ie. about 1.5% chance of being successful. You can incre…
> You can increase your chances by increasing your mining percentage. Make it a 75% attack and you have an 18% chance of success. To have a 50/50 chance of success you really need to mount about a 90% attack which is pretty ambitious. I'm not sure this is accurate. You don't need to mine 6 blocks in a row on the existing chain. Clients are programmed to recognize the longest chain, so you just need to silently mine n…
Therefore, if our malicious miner identifies that they have had poor luck and begun to fall behind the "legitimate" chain by a block or two they can start the make-a-longer-competing-chain process over again from the legitimate head with -as far as I can see- no downsides except for some lost time/resources; the main risk to them isn't really there until they commit by initiating their double-spend, something they would almost surely not do until they're confident they've acquired their own, longer competitor to the "legitimate" chain.
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Really surprised by the relatively low cost of attacking Bitcoin with 51% for one hour - claimed to be about $300k. Is this number for real? I can think of many actors for whom this is just small change, and who might have incentive to break trust in the Bitcoin network by successfully performing such an attack.
Seems like it would be very difficult to make back your $300k with a double-spend in one hour, based both on my intuition and the fact that it doesn't appear to be happening.
50% chance spend 1.1 million get 1.1 million back minus substantial overhead. Say 10% overhead although I have no idea what the actual overhead would be. So negative 100k.
50% chance spend 1.1 million + 100k overhead get 1.6 million back. Net gain of 400k
So average gain of 200k assuming you can find a market to move that much bitcoin that quickly and always assuming your creativity isn't rewarded with jail time.
People with substantial resources can find way to make money that are repeatable and don't involve finding new and exciting ways to go to jail.
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> But if you tried to sell some significant fraction of the outstanding coins then the sale price would plummet, and you'd never actually reach $5M total. Yes. But it's the same for the market cap of company stocks. So saying that "the market cap isn't truly $5M" is missing the point a bit. The market cap can truly be $5M without $5M having been invested. That's just not what market cap means.
No, this is precisely why trying to calculate the market cap of a crypto-currency is pointless. A company is a productive enterprise, that produces value for you, if you sit on shares of it. Something like bitcoin is a purely speculative instrument, that produces no value if you sit on it. The market cap for a company is an imprecise proxy for all expected revenues, discounted by time[1]. The market cap for a currenc…
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Or wait for many more confirms that the attack is impractical.
I'm not sure that is possible. If a 51% attack for 1-week costs $1-million USD to pull off (hypothetical round numbers against a hypothetical coin)... then how many confirms do you wait for? If you wait for 1008 confirms (for a transaction of $1 Million USD), then that doesn't stop the attack at all. After all, the attacker simply has to perform $2 Million USD worth of double-spends during that timeframe to make a pr…
However it the attacker has less than 50% they can still wage an attack. With 10% of mining power I’ve got a 1% chance of mining consecutive blocks. It dwindles quickly even for larger percentages and a large number of confirms makes that angle impractical.
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Well, the reality is that "attacking" a coin is much more difficult than just spending 3$ on something. You also have to actually do the double spend transactions, and hope that the person that you are stealing money from doesn't do anything about it. It is that step 2 that is actually much harder than a nieve attack might suggest.
Not really, you just have to short the coin in trading, then cover your short when your double-spend discredits the coin's security.
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I'm not sure that is possible. If a 51% attack for 1-week costs $1-million USD to pull off (hypothetical round numbers against a hypothetical coin)... then how many confirms do you wait for? If you wait for 1008 confirms (for a transaction of $1 Million USD), then that doesn't stop the attack at all. After all, the attacker simply has to perform $2 Million USD worth of double-spends during that timeframe to make a pr…
If the attacker has 50+% of mining power for the entire duration then yes it wouldn’t work as the longer things stretch out the further ahead the attacker gets (statistically). However it the attacker has less than 50% they can still wage an attack. With 10% of mining power I’ve got a 1% chance of mining consecutive blocks. It dwindles quickly even for larger percentages and a large number of confirms makes that angl…
ETC's blockchain just had over 100+ blocks change, according to the tweet.
Even with 40% of the mining power, the probability of such an event (40% mining power, 100 consecutive blocks) is 0.000000000000000000000000000000000000016%. That's a very unlikely hypothesis you're presenting.