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Messages - Come-from-Beyond

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61
General Discussion / An attack on DevShares
« on: February 09, 2015, 07:12:41 pm »
Some people mentioned DevShares as a good way to test an attack on BitShares, I tend to follow the advice. Could anyone point me to an up-to-date documentation on DevShares (whitepaper and protocols)? Also, I'd like to get a permission from the community if it's possible to get.

62
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 09:23:35 pm »
The same way you inform others that GHash is doublespending on a gambling site ... you make a post in the community, news, forums ....

We can't make shareholders re-vote, why can we make them read the forum? Also, what should be used as a proof of the words?

63
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 07:50:37 pm »
You would run a node that gathered statistics about transactions that are delayed in their inclusion from the time they were received.

So 1000 people with 25% total stake notice that their transactions are not confirmed for a long time. Votes of these people are enough to replace 51 delegates. How will they notify the others that something went wrong?

64
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 07:20:41 pm »
Its a block chain. Everything is public

I mean what protocol should I follow to detect misbehavior.

65
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 07:10:39 pm »
...misbehavior can be detected.

How?

66
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 07:09:05 pm »
There are those forging pools or whatever NXT calls them.  So we  realize you don't call them Delegates, but what happens if 51%+ of them are malicious and ignore the blocks of the minority?  Can the rest of the network recover?

Max period for delegation of power is 32767 blocks.

67
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 05:25:41 pm »
Does game theory account for people that can't be bought?

Dunno, I'm not an expert. But a cryptocurrency can't rely on trust.

68
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 04:30:45 pm »
Thank you Come-from-Beyond, for helping us harden our security model, and harden our theories backing up our current system.

It's more about whitepaper now. :)

I see that the whitepaper lacks the following:
1. Protocol that allows to detect hostile delegates (with some quantitative analysis on probabilities of detection).
2. Protocol how hard-fork is handled.

This is a serious obstacle to world domination because the outer world doesn't know what to do in extraordinary cases. It will not figure out the details by itself and will simply pick another cryptocurrency.

69
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 04:21:58 pm »
That would be true if there was only one delegate.

The proof of this statement is not presented in DPoS whitepaper, hence it's better (for security) to assume the opposite.

70
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 04:14:28 pm »
This whole thread has been focused on the implausible scenario in which most delegates are compromised. Exploring handling for such extreme cases is healthy, but it's important to keep the probability context in mind.

Actually the thread was derailed with bribery example. The point was supposed to be - if delegates control the only medium of exchange then this channel cannot be used for sending information that affect the delegates.

71
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 03:27:39 pm »
Lastly if it is clear there is an attack, and it would be, then it would be TRIVIAL to release a universally accepted hard fork that simply reset the vote on the offending delegates to 0.

How is it trivial?

72
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 03:24:22 pm »
People who accept bribes think there's a high likelihood they won't get caught.

The delegates don't know who they're screwing over in an attack but the shareholders would  know who the majority of them are.

Finding a large group of people willing to take this risk is almost completely implausible especially high trust individuals who are elected based on established reputations.

If majority accepted the bribe then you will earn nothing because your blocks will be ignored. Game theory tells that you will follow the majority as long as risk of being caught and voted-out is below some threshold. You don't know what threshold the others chose so you start observing if Bob included voting-out transactions. With non-zero probability Bob can be a honest delegate but he picks all non-voting-out transactions (pure random). What will you do? More likely you will think that Bob is rogue. There is a bias towards scenario when delegates decide to abuse the power. Sybil attack makes it less risky to go the bad route.

73
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 01:44:52 pm »
In the scenarios discussed in this thread, I define an "evil delegate" from the perspective of a stakeholder as a delegate who the stakeholder has noticed is not including valid transactions into the blockchain in a reasonable amount of time.

Other transactions may be prioritized and occupy all available space in blocks. Unconfirmed transactions can be lost in void. An eclipse attack may be conducted against one of the delegates... Rating grinding attack becomes much easier if you decide to distinguish delegates.

74
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 01:10:17 pm »
I assumed that people will update their votes to make sure they can get all 100 evil delegates replaced by good ones so that the honest chain can take over.

Now we need something to distinguish bad and good delegates.

75
General Discussion / Re: Consensus on the list of delegates
« on: February 03, 2015, 08:11:14 am »
This means that the good chain can recover in at most 51 minutes after collecting all the valid (non-expired) transactions that vote out the 100 bad delegates and replace them with 100 good ones.

What if only 99 delegates will be voted-out on the honest chain? Or someone votes-out the honest delegate on the hostile chain? We'll get two chains of the same power => double-spending made for free.

Any game that allows a minority to win can be used for malicious things...

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