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Author Topic: Merged mining for Ixcoin  (Read 4786 times)
John Tobey
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October 20, 2011, 03:45:24 AM
 #21

Can anyone point me to a fix for in the code of other alt coins where this [time travel exploit] was fixed please? Thanks.

I still think merged mining has more potential though.
It is not either/or.  You have to fix the exploit regardless of whether you do merged mining.

I've seen the "fix" (sorry, no link handy) but am left wondering, Why not update difficulty continuously?  Pseudocode:

Code:
# Constants set by chain designer
B=2016
N=600*second
DIFFICULTY[0] = 512
DIFFICULTYmin = 512

# Current difficulty as function of last block difficulty and time elapsed since last block
DIFFICULTY[i] = MAX(DIFFICULTYmin, DIFFICULTY[i-1] * B * N / ((B-1) * N + TIME[i] - TIME[i-1]))

TIMEi would be the "current" time as stored in the block header.  Validation would require that "now" >= TIMEi >= TIMEi-1.  (If a block appears with time in the future, the client would hold onto it in case it is part of the best chain when it becomes valid.)

Let's see how this fares in some pathological cases.  1. Difficulty too low.  A long sequence of blocks with little change in time: TIMEi-TIMEi-1 is close to zero, so difficulty increases by a factor of approx. B/(B-1) with each block.  Difficulty doubles every 1397 blocks (approx. B*log(2)).

2. Pool dumps coin.  Difficulty too high.  A long stretch of time without any blocks.  Current algorithms suffer.  This one decreases difficulty with the passage of time, not just the solving of blocks.  Difficulty halves in 2 weeks (approx. B*N) even with zero blocks solved.

3. Miners leave block time unchanged despite passage of real time.  They may gain from higher chain difficulty, but they will have to mine at an increasingly higher difficulty than the rest of us, and eventually that advantage will get us mining a block with updated time.

4. Time traveller visits.  Can't do much as far as I can see.  Blocks in past (before previous block) fail validation.  Blocks in future must wait for their time (and hope the chain doesn't pass them) before clients recognize them.  The lack of discreet difficulty jumps moderates profit.  Exploit thwarted by appeal to external authority (the stars, crystal oscillations, Naval Observatory, etc.) yet without requiring absolute, network-wide agreement.

5. Computer clocks all wrong.  As far as I can tell, the incentives are for accuracy.

I'm curious whether this has been proposed and discussed.  Edit: proposed in mid-2010 here, though in a simpler form suffering from use of floating-point arithmetic.  To clarify: the pseudocode is not meant to suggest use of floating point or incompletely specified operations.  No arguments against my form, but of course for the established chains there is inertia.

Can a change to the best-chain criteria protect against 51% to 90+% attacks without a hard fork?
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October 20, 2011, 05:22:38 AM
 #22


Yes, that's it. But do remember that you have to set this to switch over at a future block. Since it will cause previous diff changes to be incorrect.

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October 20, 2011, 06:14:22 AM
 #23

How come sometimes when I generate an Ixcoin block I get an extra .0005 for the reward? 

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October 20, 2011, 06:19:42 AM
 #24

How come sometimes when I generate an Ixcoin block I get an extra .0005 for the reward? 

Transaction fees are included in blocks.
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October 20, 2011, 01:47:48 PM
 #25


Thanks for that. It would require a chain split but seems easy enough.

If we'd be doing a chain split for this fix, we might as well look into merged mining too. Twobit suggested https://ixcoin.org/forum/index.php?topic=141.0 we use the MultiCoin client as the basis for Ixcoin. I'm not familiar with it yet, but apparently it supports merged mining and other altcoins already. If it keep sup with the main Bitcoin 0.4 updates then this could be a good option for Ixcoin. It would mean all supported altcoins could benefit from the same code updates.






Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
Ixcoin.org
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October 20, 2011, 01:54:36 PM
 #26

It is not either/or.  You have to fix the exploit regardless of whether you do merged mining.

I've seen the "fix" (sorry, no link handy) but am left wondering, Why not update difficulty continuously?  Pseudocode:


Interesting idea. I think the key issue (for Ixcoin and maybe other altcoins) is to get a substantial number of miners mining the chain to prevent 51% attacks & co. Maybe a continuous difficulty adjustments could help to motivate miners but we'd need more proof of concept before going with this.

Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
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October 20, 2011, 06:43:31 PM
 #27

I really like the idea of a small sales tax on a crypto-coin, like 1%-5% with the end of mining known rewards.  With a portion deleted and a portion going to miners.

1. The owners of the coin will like the deflation the amount of coin will diminish and the price will go up.
2. The businesses won't care, they will just increase the prices.   They want owners/consumers of the coin.
3. The consumer won't care all they want is something to buy.
4. The miners deserve little or nothing, however having it attached to a bigger transaction will create sort of a game.  If the economy grows, the sale tax might actually be larger than the 96.

People mine today because it is the easiest way to get coin, it adds little value and the first coin that ends the mining will benefit the most.  ixcoin is the 1st coin slated to end the mining, I just wish we could end the mining now.   
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October 20, 2011, 10:05:20 PM
 #28

So is Ixcoin actually going to be fixed?

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October 20, 2011, 10:09:21 PM
 #29

So is Ixcoin actually going to be fixed?

I'm not sure but a if I look at the difficulty increase (almost 100% in 24 hours in 10% steps) a lot of people assume it will  Grin

I still have a wallet with 3700 IXCoins, mined and speculated them.
I won't throw it away but I won't start mining yet... To uncertain, unless the creator can convince me Tongue
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October 20, 2011, 11:11:57 PM
 #30

So is Ixcoin actually going to be fixed?

I'm not sure but a if I look at the difficulty increase (almost 100% in 24 hours in 10% steps) a lot of people assume it will  Grin

I still have a wallet with 3700 IXCoins, mined and speculated them.
I won't throw it away but I won't start mining yet... To uncertain, unless the creator can convince me Tongue

Yeah, I'd say get the time travel exploit fixed first before even thinking about merged mining.

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October 21, 2011, 09:06:56 PM
 #31

Yeah, I'd say get the time travel exploit fixed first before even thinking about merged mining.

Would a fix for the time travel issue be sufficient to reassure DoubleC into reinstating his IXcoin bitparking exchange?

Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
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October 21, 2011, 10:04:39 PM
 #32

Would a fix for the time travel issue be sufficient to reassure DoubleC into reinstating his IXcoin bitparking exchange?

It couldn't hurt.  If nothing else, it might encourage more people to mine if they see that Ixcoin still has active development behind it... even if you just copy pasta Tongue  But it's still vulnerable to a 51% attack just like any other *coin.  IMHO you should just go back to a block-count based retarget schedule but retain the 400/10% adjustment coefficient, just to keep with a KISS methodology.

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October 22, 2011, 04:02:57 AM
 #33

I would also suggest that you contact BitcoinEXpress and figure out why he DS attacked Ixcoin
ixcoin on the bitparking exchange was never double-spent. i0coin was. I saw BitcoinExpress had in his signature for a while that he purchased an ipad 2 with money obtained from an ixcoin double spend - I don't know what that was in regard to.

I wouldn't open another ixcoin exchange (or any other low hash rate exchange) in their existing forms , unless I found some way of dealing with double-spends or improving the way existing exchanges work to reduce the risk.
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October 22, 2011, 07:35:55 AM
 #34

I would also suggest that you contact BitcoinEXpress and figure out why he DS attacked Ixcoin
ixcoin on the bitparking exchange was never double-spent. i0coin was. I saw BitcoinExpress had in his signature for a while that he purchased an ipad 2 with money obtained from an ixcoin double spend - I don't know what that was in regard to.

I wouldn't open another ixcoin exchange (or any other low hash rate exchange) in their existing forms , unless I found some way of dealing with double-spends or improving the way existing exchanges work to reduce the risk.


Hey Monkey Boy (Coinhumper), STFU.
For the record, I have never attacked, intended to attack or threatened to attack Bitparking in any way, shape or form. The quote in my signature was due to the Solidcoin freaks wackjobs cocksukers "enthusiast" kept saying it.

@DoubleC

I would also be interested in helping develop a way to protect low hash rate block chains I think both Ixcoin and I0coin would be ideal. My only hesitation with IXcoin is if you remember, IXC was the first to Pre-mine with 35,000 blocks I remember?

I0coin has no real dev other than Fusebox and a zero premine. Experimenting with these two chains wouldn't hurt anyone per say.

You could set up an exchange where IXC could be traded for I0C till the double spend issue is worked out. If somebody DS's your IXC all they get is I0C LOL....

Anyway what's your idea on preventing DS on low hash rate block chains?

I've got 10,000 I0C I can donate to the cause.



In reality, that's 20,000 IOC because you can double spend it Grin
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October 22, 2011, 07:41:59 AM
 #35

I certainly do not mind if all coins are merged, mine one and you mine all, that will certainly help increase the profits of mining Smiley
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October 22, 2011, 01:46:21 PM
 #36

Ok, thanks for the feedback. I'm going to look into merged mining for Ixcoin then as I don't see anyway to counter 51% attacks without a a-la-Solidcoin centralized approach.

Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
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October 22, 2011, 03:19:14 PM
 #37

I certainly do not mind if all coins are merged, mine one and you mine all, that will certainly help increase the profits of mining Smiley

And it increases survival chances of an alt-coin.
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November 03, 2011, 01:16:04 AM
 #38

Any status of this.  Seems network is dying I only connected to 5 nodes and I have always connected to 8.  I think merged mining is the way to go with a 5 coin reward to miners.
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Thomas Nasakioto


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November 03, 2011, 02:02:51 AM
 #39

Ixcoin.org should be back up soon.

Looking into merged mining. Anyone who wants to help with the coding can claim 5K from the 10K Ixcoin coding bounty.


Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
Ixcoin.org
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November 03, 2011, 02:46:33 AM
 #40

How about you do simple one first. Supposedly the time travel exploit is an easy cut and paste from what I have read around here so do that then update the source for download then people might actually have some confidence that you are going to do something and maybe help you out. It is up to you but I don't see much action from you on any front especially the one that stops/stopped people from wanting to use the coin in the first place after the i0 got hit by that exploit which is present in ix.

Yes, solving the time travel exploit wouldn't take much coding effort. However it wouldn't necessarily guarantee sufficient miner uptake for exchanges to be confident about potential 51% attacks. I believe merged mining would address this. Plus I'd rather include as much as possible in the next compulsory update, rather than having myself and all users go through the new release process twice.

Thomas Nasakioto - Upgrade to Ixcoin 0.3.24.3 before block 43,000
Ixcoin.org
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