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Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 7:40 am
by tommy
doublec wrote:tommy wrote:
Can this be hardcoded into the namecoin client software? Please provide an updated client version that will revert back to block 19100 once this attack is over.
Run a client that has a recent checkpoint and it'll refuse to accept any chain that was rewritten before that checkpoint. Are you able to do your own namecoin builds?
I just downloaded and ran this client:
http://dot-bit.org/files/namecoin_linux32.tgz
It's version 0.3.24.61, and the downloaded blockchain is up to date. I'm making a backup of the ~/.namecoin directory just in case people are going to have to do things manually after the attack is over, and a trusted copy of the pre-attack blockchain will be needed. I'm not a *coin developer, just a user.
Do you know if the 0.3.24.61 version has a checkpoint hardcoded into it, and at what block number that checkpoint would be?
Edit1:
> Are you able to do your own namecoin builds?
I haven't tried it and don't know how difficult that would be. I used to compile stuff from source many years ago when I was using Red Hat and often wanted software that wasn't available in the package repository (rpm). So if it's "compile-n-go"-easy I should be able to. Why?
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 8:01 am
by doublec
tommy wrote:
Do you know if the 0.3.24.61 version has a checkpoint hardcoded into it, and at what block number that checkpoint would be?
It does not have a checkpoint. I asked about if you could build because then you could add a checkpoint yourself.
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 8:33 am
by tommy
doublec wrote:tommy wrote:
Do you know if the 0.3.24.61 version has a checkpoint hardcoded into it, and at what block number that checkpoint would be?
It does not have a checkpoint. I asked about if you could build because then you could add a checkpoint yourself.
Oh, ok. Thanks, but I'll just wait and see how this all plays out. I have the blockchain backed up at least, in case I'll have to do something manually later.
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 9:23 am
by twobits
tommy wrote:doublec wrote:tommy wrote:
Can this be hardcoded into the namecoin client software? Please provide an updated client version that will revert back to block 19100 once this attack is over.
Run a client that has a recent checkpoint and it'll refuse to accept any chain that was rewritten before that checkpoint. Are you able to do your own namecoin builds?
I just downloaded and ran this client:
http://dot-bit.org/files/namecoin_linux32.tgz
It's version 0.3.24.61, and the downloaded blockchain is up to date. I'm making a backup of the ~/.namecoin directory just in case people are going to have to do things manually after the attack is over, and a trusted copy of the pre-attack blockchain will be needed. I'm not a *coin developer, just a user.
Do you know if the 0.3.24.61 version has a checkpoint hardcoded into it, and at what block number that checkpoint would be?
Edit1:
> Are you able to do your own namecoin builds?
I haven't tried it and don't know how difficult that would be. I used to compile stuff from source many years ago when I was using Red Hat and often wanted software that wasn't available in the package repository (rpm). So if it's "compile-n-go"-easy I should be able to. Why?
A patch to add checkpoints to 0.3.24.61 is @
https://github.com/zamgo/namecoin/commi ... 628#diff-0
Binaries built with that patch included are @
http://www.wuala.com/jbw9/pub/Bitcoin/n ... eckpoints/
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 11:24 am
by Seraphim401
Ok.I downloaded the patched binaries.
So all I have to do now is make a backup of the block chain?
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 11:54 am
by thirdlight
So, thinking about checkpoints.... I could add
Code: Select all
(nHeight == 19001 && hash != uint256("0x00000000000000000000000000000000000000000000000000000000000000001"))
to my client, wait for nodemaster, or other trusted miner to declare the hash for block 19001, and update my client, adding
Code: Select all
(nHeight == 19002 && hash != uint256("0x00000000000000000000000000000000000000000000000000000000000000001"))
In effect manually verifying the block chain.
Anyone who has my ip as a "connect" would only get the "honest" chain, albeit slowly.
Problems:
- It's slow. I have to get home from work, playgroup, whatever to update.
- I have to be trusted.
- I have to trust an "honest" miner.
Solutions
- The network is already really slow, & I'd swap slow for destroyed.
- I trust me, but you don't. Maybe if there were 20 of me, you could trust any 8 you choose.
- Hmm. I think I can trust a couple.
Any good?
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 12:30 pm
by paraipanakos
nice try twobits, none of those hashes exist... grrr but hey thanks for implementing the method, I would put my custom block hashes in place
edit: nvm, i just realize that namecoin block explorer can't search blocks by hash, sorry, good hashes in place
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 12:38 pm
by twobits
paraipanakos wrote:nice try twobits, none of those hashes exist... grrr but hey thanks for implementing the method, I would put my custom block hashes in place
I took the hashes from zamgo's patch I linked to. I compiled and ran it on a virutal machine, and with those checks in place it successfully downloaded the blockchain.
http://explorer.dot-bit.org/b/500
http://explorer.dot-bit.org/b/18932
show hashes that match also, so testing and the block explorer say otherwise, why do you say they do not exist?
Re: Namecoin is Prime for a 51% attack
Posted: Tue Sep 13, 2011 11:46 pm
by moa
BitcoinEXpress should remember the age old adage:
bulls make money,
bears make money,
pigs get slaughtered.
He seems to forget that the mining pool itself is a centralised structure, probably the most vulnerable out-growth of the bitcoin network.
Re: Namecoin is Prime for a 51% attack
Posted: Wed Sep 14, 2011 2:45 am
by vinced
I released version nc0.3.24.62 with a corrected lockin patch from makomk. Please test.
For now, I suggest we lock in often while we investigate a more permanent solution to the timing attack.
We definitely need more hash power too and that should come with merged mining. If an attack starts, we could restart the chain at the last lockin with merged mining.