Quote from: d5000 on September 11, 2018, 06:41:57 AM

Quote from: Zin-Zang on September 11, 2018, 04:49:06 AM

PoW miner has no such wait period and can run continuous succeeding attacks with no wait time.

But he has to pay for the electricity all the time.

True, but to mount a successful 51% attack , he is already showing an access to extreme financial resources.
And he could double spend early to offset the costs.
In the VIDEO: Nightmare of 51% Attack - part 2 ,
http://redpinata-development.com/bitcoin-academy/index.php/reader/items/non-technical-overview.html
It is explained how the ASIC manufacturers could profit by 51% making all of the blocks.
Governments & Large Corporations would have the financial resources to pull off an extended 51% attack.

Quote from: d5000 on September 11, 2018, 06:41:57 AM

Quote from: Zin-Zang on September 11, 2018, 04:49:06 AM

I don't care if the guy own 80% of a proof of stake coin, by combining all of my coins into a single block, and using max coin age, I could get 1 block added per dormant period and he can't stop me therefore including my transactions in the blockchain.

OK, you may have a point here. depending on the length of the "dormancy" period. But there have to be some actively minting whales for that.
(Maybe Anonymint could find some trick here, however Wink

)

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Bottlecaps is a prime example, it was 51% attacked multiple times,
all they did was reimburse Cryptopia for the double spend coins, and as of today it is still trading there,
with increased required confirmations to 200 and running a checkpoint server.

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(They could have done a rolling checkpoint and stayed decentralized, but they choose a centralized solution.)

But only with an extremely long confirmation time, and that was my point. Bottlecaps is a very small coin and not really used for something useful. It's simply a pennystock for gambling on exchanges, so nobody cares about it requiring so many confirmations. A coin with real merchants and clients waiting for goods and services wouldn't be able to recover "as a currency" without a hard fork.

We always heard that to be the case, but as long as the double spend only had a few victims, I am not so certain.
If it were fiat , it would be akin to someone using counterfeit money to buy good or services.
In real life , No one reimburses the person that sold his car for counterfeit money ,
they just try and arrest the guy who did the counterfeiting and only give back the car , if they catch the counterfeiter, and track down the car.
Replacing the doublespend amount with a hard fork implies a centralized authority making that decision,
a truly decentralized resource such as gold , no one makes the pretense that stolen gold will be replaced unless the person that stole it is apprehended.
It is funny, we want crypto to be decentralized, but we also want centralized protections.

Quote from: d5000 on September 11, 2018, 06:41:57 AM

Quote from: Zin-Zang on September 11, 2018, 04:49:06 AM

I think the fear is that an attacker could focus his attack specially trying to fork the network into more than one branch.

Agree here, but I have to investigate more.

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Easy ways to mitigate this is choose random times or allow set times in the wallets to block reorgs between a time range of between 1 hour to 2 days.

Would all clients block the same reorgs? Hm, looks complicated.

That is the trick , all clients would not block the same reorgs, (So it does need enough confirmations to be safe from a normal reorg)
it would make it incredibly complicated to focus an attack to fork a coin, if you don't know where to focus your attack.
So far no one has attacked blackcoin reorg limit, so we have little history to calculate the best settings.

Quote from: d5000 on September 11, 2018, 06:41:57 AM

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*FYI: Blackcoin choose ~8.3 hours for their no reorg limit.*
Currently the lowest one, AFAIK.

Interesting, thanks. They're one of the more interesting "traditional" PoS coins out there.

Quote from: Zin-Zang on September 09, 2018, 08:38:58 AM

Since the network always accepts the longest chain, he would end up in creating every new confirmation and getting full control over the blockchain.

OK, here it seems you're right, my bad. While others can find blocks, the dominant miner/attacker would simply orphan them. In this case PoS has a point.

I am however not sure if there is really no way to censor transactions with PoS coins. I have read something somewhere, but have to search it, I think it was a post by Anonymint.

There is only 1 way to Censor a Proof of Stake coin Transactions for an extended period,
but it is not 51% attack , it is 100% control of the full nodes, (Which is almost impossible)
the attacker has to control every single full node in existence as such he be able to accept or block whatever he wished.
But the same hold true for if an attacker controlled every single node on a PoW network,
he basically controls the consensus rules since their would be no competing viewpoints.
If that happens either coin is completely centralized to his rule system.

100% Full Node Domination can only be carried out by a collusion of the World's Governments.
If even 1 small country opted out of the collusion , the rest would fail in the attempt.

Quote from: einax_oliver on September 11, 2018, 09:06:49 AM

I think modern POS (like Casper, or deligated POS) have a solution on the majority of the issues described by OP. Casper (should) effectively punish malicious actors if hard fork occurs, and delegated POS makes it nearly impossible for a malicious actor to gain enough support to be voted into validator position. They both have their issues (like major centralization of DPOS) but my strong belief they should be developed and tested at scale anyway.

check out Casper docs for more info https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQs

Casper is a Frankenstein of proof of stake design, trying to fix @nas , when @nas is not even a real problem.
(Just a myth to scare the newbies. No one that really understands PoS is worried about @nas in the least.)
Ethereum will be crushed by it's insane blockchain bloat or its full nodes dominated by rich elite.
Vitalik's interference with multiple hard forks has proven eth to be centralized.

Delegated Proof of Stake , opens up the possibility of corruption of the Delegates nodes.
We have to look no further than the US political system to see that delegates only rule leads to disaster.
As the Delegates vote in favor of their personal self interests and ignore the Greater Good.
We have over 200 years of proven history that delegate rule is corruptible.