Cleanup: I'll attack some coins - I owned APEXcoin for 90 blocks - page 7.

Biomech

legendary

Activity: 1372

Merit: 1022

Anarchy is not chaos.

Quote from: jones_ on January 18, 2015, 09:39:39 PM

Quote from: Biomech on January 18, 2015, 09:04:50 PM

Not being a programmer, I could be totally wrong here, but I thought that in many coins with checkpointing, it's simply a flag set in the blockchain every so often. I know that peercoin used central checkpointing for a while, but then dropped it in favor of a revised system that depended on live nodes rather than any central checkpointing mechanism. Am I wrong in this?

As for NXT, other than being a cast iron bitch to set up a NXT daemon, I have no opinion on it.

checkpointing a cryptocurrency is believed to be centralized because for the checkpoint to have any effect (different than what the normal consensus would have come up with) it would have to be created by a group of people other than the original consensus group, most of the time this is the developers, so the coin with checkpoints would be centralized around the group of developers.

a good resource: links.org/files/decentralised-currencies.pdf (newbie here so probably wont show up)

Thanks, I'll check that out. My knowledge continues to evolve due to people like you Cheesy

cynicSOB

member

Activity: 106

Merit: 10

yes, sometimes I'm a cynical SOB

Quote from: TwinWinNerD on January 18, 2015, 05:50:32 PM

Quote from: Rent_a_Ray on January 18, 2015, 05:36:01 PM

NXT is centralized. There is no need for centralized checkpoints.

What is the central authority you speak of?

he may be referring to the initial distribution of the coins...

NXT's checkpointing is a nice idea that prevents "long range attacks" or "n@s-style history rewrites". But of course it has the risk of splitting the network and it won't help against this short-range attack.

cynicSOB

member

Activity: 106

Merit: 10

yes, sometimes I'm a cynical SOB

Quote from: Crestington on January 17, 2015, 11:13:37 PM

Split/combine threshold at 200,000 coins at 10 days

wtf is this? are you restricting splitting coins? this restricts valid use cases of a currency...

Quote from: Crestington on January 17, 2015, 11:13:37 PM

By the way you describe your attack, the result would cause financial detriment to you since you would be paying tens of thousands in fees but Stakers would also get all those Coins plus 10% more!.

why pay a lot in fees? the splitting is done in only one transaction. PPC destroys fees, they don't go to the stakers, but others do distribute the fees...

jones_

member

Activity: 63

Merit: 10

Quote from: Biomech on January 18, 2015, 09:04:50 PM

Not being a programmer, I could be totally wrong here, but I thought that in many coins with checkpointing, it's simply a flag set in the blockchain every so often. I know that peercoin used central checkpointing for a while, but then dropped it in favor of a revised system that depended on live nodes rather than any central checkpointing mechanism. Am I wrong in this?

As for NXT, other than being a cast iron bitch to set up a NXT daemon, I have no opinion on it.

checkpointing a cryptocurrency is believed to be centralized because for the checkpoint to have any effect (different than what the normal consensus would have come up with) it would have to be created by a group of people other than the original consensus group, most of the time this is the developers, so the coin with checkpoints would be centralized around the group of developers.

a good resource: links.org/files/decentralised-currencies.pdf (newbie here so probably wont show up)

Biomech

legendary

Activity: 1372

Merit: 1022

Anarchy is not chaos.

Not being a programmer, I could be totally wrong here, but I thought that in many coins with checkpointing, it's simply a flag set in the blockchain every so often. I know that peercoin used central checkpointing for a while, but then dropped it in favor of a revised system that depended on live nodes rather than any central checkpointing mechanism. Am I wrong in this?

As for NXT, other than being a cast iron bitch to set up a NXT daemon, I have no opinion on it.

BlindMayorBitcorn

legendary

Activity: 1260

Merit: 1116

Quote from: TwinWinNerD on January 18, 2015, 05:50:32 PM

Quote from: Rent_a_Ray on January 18, 2015, 05:36:01 PM

NXT is centralized. There is no need for centralized checkpoints.

What is the central authority you speak of?

TwinWinNerD

legendary

Activity: 1680

Merit: 1001

CEO Bitpanda.com

Quote from: Rent_a_Ray on January 18, 2015, 05:36:01 PM

NXT is centralized. There is no need for centralized checkpoints.

What is the central authority you speak of?

YarkoL

legendary

Activity: 996

Merit: 1013

Quote from: achimsmile on January 18, 2015, 04:42:45 PM

Checkpoints are not always centralized. Nxt uses a system where each client sets his own rolling checkpoint 720 blocks in the past.

isn't NXT block generation
time about one in a minute? Then if something went wrong
and 12 hours went by with two or more competing chains,
you'd have a set of hard-coded forks. Or is there some
additional mechanism to prevent that?

Rent_a_Ray

legendary

Activity: 1344

Merit: 1046

NXT is centralized. There is no need for centralized checkpoints.

achimsmile

legendary

Activity: 1225

Merit: 1000

Quote from: Rent_a_Ray on January 18, 2015, 02:24:52 PM

Quote from: YarkoL on January 18, 2015, 02:03:17 PM

Quote from: cynicSOB on January 18, 2015, 01:29:21 PM

This would mitigate the attack, but it's not a good thing as it benefits the "rich" over the "poor".

I hardly think that would deter anyone who has
investment in the coin. Just the same as with centralized
checkpointing. Philosophy drops when money talks.

Checkpointing is always centralized. Owners of the private master key (like theymos) are able to set checkpoints on demand.

Cheers,
Ray

Checkpoints are not always centralized. Nxt uses a system where each client sets his own rolling checkpoint 720 blocks in the past.

armin22

sr. member

Activity: 252

Merit: 250

I would actually love to see where this goes.

YarkoL

legendary

Activity: 996

Merit: 1013

Quote from: Rent_a_Ray on January 18, 2015, 02:24:52 PM

Checkpointing is always centralized. Owners of the private master key (like theymos) are able to set checkpoints on demand.

Quite so, but whereas in Bitcoin it is more an expediency
that prevents new nodes getting lost while downloading the chain,
in PoS it becomes essential part of the security model, thus
effectively undoing the decentralization aspect.

Rent_a_Ray

legendary

Activity: 1344

Merit: 1046

Quote from: YarkoL on January 18, 2015, 02:03:17 PM

Quote from: cynicSOB on January 18, 2015, 01:29:21 PM

This would mitigate the attack, but it's not a good thing as it benefits the "rich" over the "poor".

I hardly think that would deter anyone who has
investment in the coin. Just the same as with centralized
checkpointing. Philosophy drops when money talks.

Checkpointing is always centralized. Owners of the private master key (like theymos) are able to set checkpoints on demand.

Cheers,
Ray

YarkoL

legendary

Activity: 996

Merit: 1013

Quote from: cynicSOB on January 18, 2015, 01:29:21 PM

This would mitigate the attack, but it's not a good thing as it benefits the "rich" over the "poor".

I hardly think that would deter anyone who has
investment in the coin. Just the same as with centralized
checkpointing. Philosophy drops when money talks.

inBitweTrust

hero member

Activity: 658

Merit: 501

Quote from: cynicSOB on January 18, 2015, 01:38:00 PM

Not litecoin, but litecoin testnet: more like 11 MH/s
but is it worth it?
there's no need to prove anything by attacking, just go to hash rental site and see how much it costs to rent that for an hour.

edit: I felt attacking POS was needed to prove the point, because the point has been made and ignored many times.

I'll say it again just in case: you don't need 51% of the supply, you need 51% of the staking weight (actively forging stake, or whatever you call it). And for most coins, that's about 5% of the supply. There's no secret attack. Only splitting the staking weight so it's not affected by each block you mine/mint/forge/whatever.

There are already many examples of both SHA256 and Scrypt coins being attacked so wasting time on the litecoin testnet where coins with the exact same algo have been attacked is not needed.

With PoS there are different variations where they make wild claims like impossible to be attacked and despite you proving yourself with Apex they will merely deflect by claiming their algo is different. Better to focus on PoS.

Rent_a_Ray

legendary

Activity: 1344

Merit: 1046

Quote from: cynicSOB on January 18, 2015, 01:29:21 PM

really? meh.... why whould they pay?

Because of the safety and the future of CryptoCurrencies.
If you are able to attack LTC testnet I would spend some bucks. (If you tell us how to reconstructing the attack)

Cheers,
Ray

cynicSOB

member

Activity: 106

Merit: 10

yes, sometimes I'm a cynical SOB

Quote from: inBitweTrust on January 18, 2015, 08:15:42 AM

Litecoin would be too expensive to attack. Not likely.

https://bitcoinwisdom.com/litecoin/difficulty

1,282 GH/s

Not litecoin, but litecoin testnet: more like 11 MH/s
but is it worth it?
there's no need to prove anything by attacking, just go to hash rental site and see how much it costs to rent that for an hour.

edit: I felt attacking POS was needed to prove the point, because the point has been made and ignored many times.

I'll say it again just in case: you don't need 51% of the supply, you need 51% of the staking weight (actively forging stake, or whatever you call it). And for most coins, that's about 5% of the supply. There's no secret attack. Only splitting the staking weight so it's not affected by each block you mine/mint/forge/whatever.

cynicSOB

member

Activity: 106

Merit: 10

yes, sometimes I'm a cynical SOB

Quote from: BlindMayorBitcorn on January 17, 2015, 11:58:33 PM

OP doesn't need cheer he needs BTC. It takes money to own a coin

hehe.. well said

cheers don't hurt though Grin

cynicSOB

member

Activity: 106

Merit: 10

yes, sometimes I'm a cynical SOB

Quote from: Rent_a_Ray on January 18, 2015, 07:51:37 AM

Quote from: cynicSOB on January 17, 2015, 10:38:58 PM

And a warning: most POW coins are not safe! it's easy to cheaply rent enough hashrate to attack a lot of coins with low to medium hashrate. Only the biggest ones are good.

Start with Litecoin Testnet

If you are right, many honest coins will pay you a tax for your work.

Cheers

really? meh.... why whould they pay?

Quote from: bitcoinpaul on January 18, 2015, 09:45:33 AM

Quote from: inBitweTrust on January 18, 2015, 09:37:50 AM

Yes, I am no expert on NxT , but from what I understand a higher weight is given to large stakes in a single account vs many small ones as well.

Indeed. The gain of weight with one big account is small but exists.

This would mitigate the attack, but it's not a good thing as it benefits the "rich" over the "poor". If I'm not mistaken, in nxt the difference is so small that it doesn't matter.
BTW: you say "accounts" but is it accounts or tx outputs that are used to forge? in PPC you don't mint with your addresses, it's unspent outputs that are used to mint.

I just made my "cynicSOB" account at nxtforums, so I have the same user name there.

achimsmile

legendary

Activity: 1225

Merit: 1000

Quote from: Maestro1 on January 18, 2015, 09:55:28 AM

Yes, either 1000 x 0.001% or 1 x 1%. It's not the number of transactions, it's the number of coin blocks. Each block stakes once until it matures again (8 hours or whatever), if you have 1000 small blocks in your wallet, you can stake 1000 times right after the other and current implementations give you the full weight of your wallet in the competition for staking, giving you a great chance of finding consecutive blocks.

So basically in simple terms, current implementations give you 1000 x 1%. That's the problem.

Which specific PoS implementation are you talking about?

Topic: Cleanup: I'll attack some coins - I owned APEXcoin for 90 blocks - page 7. (Read 17296 times)