Topic: Security analysis of PoW/PoS hybrids with low PoW reward - page 5. (Read 13268 times)

Blocks may have timestamp different from real time. This allows keeping low difficulty. Time window is limited but enough for this attack.


No.


Again, one PoS block will not stop attack. Two will.

You dont need 51% of the coins, you need 51% of the coin age
So, with a pure pos coin that has no upper limit for coin age it might be enough to own 10% of the coins and let them age long enough......

Going back to the OP,
"At such difficulty a sequential chain of PoW blocks can be mined in a flash."

And what artiface said,
"If the difficulty is very low due to low network hash rate then applying a substantially higher hashrate can cause many POW blocks to be generated quickly, much quicker than the target rate."

How exactly is this possible, particularly with difficulty re-targeting every block? Also, it is my understanding that not only would the difficulty of finding a PoW block go up, but the difficulty of finding a PoS would go down in response as well.


Additionally, no matter how fast you can manage to generate a string of PoW blocks there is no way to know with certainty that a PoS block wont be randomly generated within that time and interrupt the string? The best you could do is estimate based on the average block time, right? But this would be further complicated since the chance of finding a PoS block is increased by PoW blocks being found.

Attacker should build a chain longer than main. The more he waits the less chance to success.


Yes, this attack has not 100% chance to success. The point is that average block time is known.
One honest PoS block will not stop attack. Two will.

Colossuscoin is 100% Proof of Stake through Pow/Pos. It it the oldest Proof of stake only coin and I started working with it about 4 months ago, right after it finished Pow and became POS only.

But like you said "Attacker should wait for 1 PoS block and delay announcing this block." Why couldn't this process be simply reiterated to form a string? You wouldn't need to "find" >2 blocks in a row, you would just need to announce them in a row. Or am I missing something?

My edit of what I said above, must have been editing while you responded:
"So, in that case, what is preventing an attacker from waiting for multiple PoS blocks and delaying announcing the multiple PoS blocks to form a string of PoS blocks similar to a TX attack chain like the one anonymousg64 was talking about? If it is not possible to wait/delay more than one block per wallet, then one could easy use multiple wallets. If the timing of generating/announcing a single PoS block can be controlled, what is preventing reiteration of the process to control a series of single blocks?
Also, what would prevent another block from being announced at that same time or right before you? Say you control when you can announce your PoS block, but does that mean you can control when other people generate/announce theirs?"

Similar to mercSuey's point that PoS is a stochastic process,

What would prevent another block from being announced at that same time or right before you? Assuming you can control when you can announce your PoS block, does that mean you can control when other people generate/announce theirs?

PoS block is a stochastic process.  You say this like it's a given that it can be done...it's not.

I'm sure he does. But he has stated his thinking and now it is time to test it. If not, well...

At this point we all need concrete facts.

Nothing prevents. Chance to find even 2 blocks in a row is low.
Long chain of PoS blocks is realistically only for exchanges with old coins in cold wallet.

Ya markm knows what hes talking about.. But rather then talk gibberish its better to simply try a demo coin like last poster said.. run fast hash on non mined pow with low rewards and see if you cam break it before pos catches on... Would be cool to know once and for all.. maybe a curious dev can do this to put an end to all the shitcoins with pos claiming its the greatest thing when sunny king hasnt even explained himself yet regarding his fix...

Well unless there is some kind of actual effort to collect objective facts about the matter it's not worth paying any attention to a lot of talk.

Until there is that's pure FUD

So, in that case, what is preventing an attacker from waiting for multiple PoS blocks and delaying announcing the multiple PoS blocks to form a string of PoS blocks similar to a TX attack chain like the one anonymousg64 was talking about? If it is not possible to wait/delay more than one block per wallet, then one could easy use multiple wallets. If the timing of generating/announcing a single PoS block can be controlled, what is preventing reiteration of the process to control a series of single blocks?
Also, what would prevent another block from being announced at that same time or right before you? Say you control when you can announce your PoS block, but does that mean you can control when other people generate/announce theirs?

Also though by the sound of it they can separately and independently conduct their attacks?

If so then maybe for example a PoW attack can be accomplished and over and done with then a PoS block or series of blocks come along taking the success of the attack as valid accomplished fact and building upon it?

And maybe vice-versa also?

So that although they are two independent separate means of securing a chain they are also two separate and independent vulnerabilities whereby attacks can be performed?

-MarkM-

thats pure speculation

It would not be the same as a standalone PoS system; rather, what it is is a PoS system plus a pathetically weak work PoW system which completely sidesteps aka does an end run around the PoS, so that the PoW attacker can attack without the PoS system getting in the way of the attack. Basically the PoS part is almost irrelevant given that the PoW attacker can do their attack and run with the loot before PoS even notices or acts?

Possibly the PoS might even lock into place the success of the attack, by building on a chain that already has the attack in place as having happened, over and done with, fait accompli ?

-MarkM-

Maybe dev should build test coin and use 51% premine for attack to see what happens that way no damage to existing coins

Attacker should wait for 1 PoS block and delay announcing this block.

There's only one way to find out and that is to pick a target, attack, and see what happens.

I would say this to OP
People who live in glass houses shouldn't throw stones.

I have still not seen any good proofs around Sunny's PoS methods.

Someone pointed out a gaping hole once upon a time, he claimed to fix it but refused to explain, and since then everyone seems to have run along in blissful ignorance blindly spawning clones of the mysterious unexplained but according to its author fixed system.

Which might even by why no one has bothered to actually implement either of the methods of PoS that discussions in the development and technical section had eventually managed to come up with that seemed as if they might actually be able to work.

(Sunny was proud not to have even read any of the research, claiming he simply came up with an idea out of the blue himself and flew with it. Then on having it pointed out that it was utterly broken/flawed/vulnerable, claimed to have come up with a fix out of the blue himself, that he refused to explain.)

-MarkM-