Quote from: DeathAndTaxes on May 16, 2014, 09:30:06 PM

Quote from: Eadeqa on May 16, 2014, 08:25:58 PM

Quote from: DeathAndTaxes on May 16, 2014, 07:26:53 PM

snip

https://nxtforum.org/general/how-does-nxt-fix-the-nothing-at-stake-problem/msg22882/#msg22882

Quote

Hehe, so sad D&T is not registered on this forum. Could anyone ask him the following:

Alice wants to attack the blockchain.
She owns private keys of 400 accounts totalling to 75% of the stake.
She is planning to rewrite the history from block 5'000.
Legit chain is at block 5'300 (less than 720).
Cumulative difficulty at block 5'000 is 8'000'000.
Cumulative difficulty at block 5'300 is 9'000'000.
How many SHA256 operations in average it's necessary to do to find a branch where cumulative difficulty at block 5'300 is at least 9'000'001?
Hint: Blocks from 5'000 to 5'300 were forged by 100% of the stake..

You can register to answer him directly on that forum

Yeah when the thread is filled with insults before a countering view is even posted I don't really see the point. Still the example is flawed. There is no assumption that all of Alice's "old coins" would be contributing to the stake. 100% of the money supply isn't being used for forging it isn't a valid assumption that 100% of the coins she sold would be used as well. Still it is possible depending on how much stake Alice had and how much of it ends up supporting the main chain she might not be able to sell all of the coins. The attacker may only have reduced amount at risk rather than nothing at risk scenario.

And
https://nxtforum.org/general/how-does-nxt-fix-the-nothing-at-stake-problem/msg22968/#msg22968