Quote from: valarmg on January 17, 2015, 01:15:32 PM

I'm incredulous about it being easy/cheap to get 10% of a stake of a well functioning coin. If you can get 10% of a stake without buying and want to profit from it, the easiest way is not to give back the 10%, and sell the coins on the market.

If you have the resources to get 10% of a PoS coin, often the price to buy enough hashrate to control a PoW coin is much less than 10%. I don't see how the incentives are drastically different. Usually owning a coin gives more incentive to not damage the coin than owning hardware does. For example, say bitcoin falls more, and lots of bitcoin mining rigs get shut off. Someone who doesn't own any bitcoin, and has lots of unprofitable bitcoin miners could just launch an attack at very low cost. Maybe put money on some shorts on bitfinex to offset the cost of electricity while attacking.

Banks and exchanges already have far greater than 10% stake for certain PoS coins right now. I am not discussing a hypothetical. It is also likely that a few Nxt users have over 10% stake.

Quote from: valarmg on January 17, 2015, 01:19:22 PM

Source? As I understand it, he is still deciding between a PoS/PoW combo and full PoS.

https://www.youtube.com/watch?v=qPsCGvXyrP4
More specifically, Ethereum will be a hashimoto dagger IO bound PoW consensus mechanism.
The latest under review is here under PoC7:

https://github.com/ethereum/cpp-ethereum/wiki
http://gavwood.com/Paper.pdf

He may use both however:
https://blog.ethereum.org/2015/01/10/light-clients-proof-stake/

Whether he uses straight PoW or PoW/TaPoS the point to consider is that he has thoroughly studied the vulnerabilities within PoS variations and deems them to have insufficient security alone without PoW.

Quote from: valarmg on January 17, 2015, 01:19:22 PM

So just extend the number of confirmations to 30, then short range attack becomes impossible. (6 confirmations on bitcoin is an hour, so a shorter block PoS coin would still take less time than bitcoin confirmation)

20 Blocks , not confirmations. The attack would have still occurred whether you wait for more confirmations or not. waiting for 30 confirmations simply means that you could avoid participating in an illegitimate transaction, but the attack still occurred. 20 blocks is merely the window the attack needs to occur in for NxT, once the attack occurs the network will need to perform a hardfork, or rollback the blockchain to recover which has its own set of problems.

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TaPoS can be used with PoW to improve the security of Bitcoin like one example I provided:

Quote from: inBitweTrust on January 06, 2015, 03:05:01 AM

Sidechain or not. No need for burning bitcoins, as someone could simply create a TaPoS blockchain that mirrored and synced the distribution of BTC and than have a wallet acknowledge both blockchains but have the TaPoS layer hidden where only BTC is used and the TaPoS layer acts to add another form of security that could have 1-30 second confirmation times in addition to PoW 10 min confirmation times.

I.E... pay for a cup of Coffee the confirmations start rolling in this way:
TaPoS 1 second confirmation, TaPoS 3 second confirmation, TaPoS 5 second confirmation, TaPoS 10 second confirmation, TaPoS 30 second confirmation, TaPoS 1 min confirmation, TaPoS 3min confirmation, TaPoS 5 min confirmation,TaPoS 7min confirmation, PoW Bitcoin 1st confirmation ~10min, TaPoS 13min confirmation, ect...

This would allow you to have instant confirmations and better security because now you are trusting full nodes and miners and you could detect a PoW 51% attack if the TaPoS confirmations weren't confirming while the PoW confirmations were.

You wouldn't even need a softfork or hardfork to accomplish this, just a TapoS blockchain and a wallet that acknowledged it.