Testnet Merged Mining Block Number

nodemaster
Posts: 172
Joined: Wed Jun 15, 2011 12:46 pm
os: linux

Re: Testnet Merged Mining Block Number

Post by nodemaster »

Thanks to s3harvey who donated more than 3Ghash/s on testnet we have more than 120 blocks generated on merged mining testnet. This blockchain is now nearly 130 blocks ahead the vanilla testnet blockchain. We now have a couple of freshly minted merged mining testnet coins. If you want some for testing you can either mine on https://alpha.masterpool.eu (which is set to instant payout and rather fast ATM) or you can trigger me. I'll send you some coins for testing. But please make sure, that you have the modified client mentioned above.

The pool (and its namecoind as well as its bitcoind) are running without any flaws. But in order to double supervise it I'd like to crowd source this process. For that reason I put the raw debug.log on the webserver. Interested people are welcome to review it (You might want to grep -v all unnessecary lines):

https://alpha.masterpool.eu/files/namec ... ug.log.bz2
https://alpha.masterpool.eu/files/bitco ... ug.log.bz2

This are the logfiles from fresh wallet.dat until the first namecoin block was verified by 120 peers.
Access .bit domains with Firefox in 4 easy steps: https://masterpool.eu/proxy
MasterPool Namecoin Mining Pool

vinced
Posts: 63
Joined: Wed May 18, 2011 1:16 am

Re: Testnet Merged Mining Block Number

Post by vinced »

I have version nc0.3.24.54-rc4 up. This version fixes an exploitable bug where the same work can be used to submit multiple auxiliary blocks, by adding multiple auxiliary trees to the parent coinbase. This version only allows one auxiliary chain tree. Someone should ask luke-jr if this is the bug he found.

This version also sets the starting merged mining block on testnet to zero and advances the client version.

It would be useful if the namecoin block explorer showed the block nVersion. This would allow us to see what % of the mining power is using the merged mining patches.
!v | Namecoin founder | https://dot-bit.org/

doublec
Posts: 149
Joined: Mon May 23, 2011 12:47 am
os: linux
Location: Auckland, New Zealand
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Re: Testnet Merged Mining Block Number

Post by doublec »

vinced wrote:I have version nc0.3.24.54-rc4 up. This version fixes an exploitable bug where the same work can be used to submit multiple auxiliary blocks, by adding multiple auxiliary trees to the parent coinbase. This version only allows one auxiliary chain tree. Someone should ask luke-jr if this is the bug he found.
He pretty much suggested he was trolling previously in the channel about exploiting a bug. With regards to this one:
15:33 < luke-jr> interesting idea
15:33 < luke-jr> no, that hadn't occurred to me
...
15:34 < luke-jr> that would have been a pretty big bug
15:34 < luke-jr> non-obvious too

vinced
Posts: 63
Joined: Wed May 18, 2011 1:16 am

Re: Testnet Merged Mining Block Number

Post by vinced »

nodemaster wrote:Thanks to s3harvey who donated more than 3Ghash/s on testnet we have more than 120 blocks generated on merged mining testnet. This blockchain is now nearly 130 blocks ahead the vanilla testnet blockchain. We now have a couple of freshly minted merged mining testnet coins. If you want some for testing you can either mine on https://alpha.masterpool.eu (which is set to instant payout and rather fast ATM) or you can trigger me. I'll send you some coins for testing. But please make sure, that you have the modified client mentioned above.
...
Thank you for taking the initiative with testing. I decided to set the starting point for testnet to zero, since we can always reset it.
!v | Namecoin founder | https://dot-bit.org/

vinced
Posts: 63
Joined: Wed May 18, 2011 1:16 am

Re: Testnet Merged Mining Block Number

Post by vinced »

doublec wrote:
vinced wrote:I have version nc0.3.24.54-rc4 up. This version fixes an exploitable bug where the same work can be used to submit multiple auxiliary blocks, by adding multiple auxiliary trees to the parent coinbase. This version only allows one auxiliary chain tree. Someone should ask luke-jr if this is the bug he found.
He pretty much suggested he was trolling previously in the channel about exploiting a bug. With regards to this one:
Good to know. Thank you for following up with him.
!v | Namecoin founder | https://dot-bit.org/

doublec
Posts: 149
Joined: Mon May 23, 2011 12:47 am
os: linux
Location: Auckland, New Zealand
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Re: Testnet Merged Mining Block Number

Post by doublec »

vinced wrote:I have version nc0.3.24.54-rc4 up. This version fixes an exploitable bug where the same work can be used to submit multiple auxiliary blocks, by adding multiple auxiliary trees to the parent coinbase. This version only allows one auxiliary chain tree. Someone should ask luke-jr if this is the bug he found.
There was some discussion about this fix on #bitcoin-dev between luke-jr (Eligius pool owner) and forrestv (p2pool developer). There seem to be coinbase conflicts with these other developers:
16:10 < forrestv> grah, that commit makes merged mining incompatible with p2pool...
16:10 < luke-jr> forrestv: it does?
16:11 < forrestv> yes. before, you could stick the aux reference anywhere in the coinbase
16:11 < forrestv> p2pool takes up the start of the coinbase with its own information, but leaves all the rest free as a nonce
16:11 < forrestv> which you could stick the aux reference in
16:13 < luke-jr> wait, that patch requires it to be at the start? :|
16:13 < luke-jr> that conflicts with my stuff too
16:13 < luke-jr> and makes multiple aux chains impossible
16:13 < luke-jr> that's a retarded fix
16:14 < forrestv> well, the aux reference is indistinguishable from random data, as it is, more or less
16:14 < forrestv> i guess adding some sort of unique header and making sure that only one existed would make more sense?
16:14 < luke-jr> forrestv: irrelevant
16:14 < luke-jr> no
16:14 < forrestv> then what?
16:14 < luke-jr> just only accept an upstream-block once in the aux chain
16:14 < luke-jr> duh
I asked luke-jr if he could come on here and explain but he wasn't interested.

vinced
Posts: 63
Joined: Wed May 18, 2011 1:16 am

Re: Testnet Merged Mining Block Number

Post by vinced »

doublec wrote:There was some discussion about this fix on #bitcoin-dev between luke-jr (Eligius pool owner) and forrestv (p2pool developer). There seem to be coinbase conflicts with these other developers:
...
I asked luke-jr if he could come on here and explain but he wasn't interested.
Version nc0.3.24.55-rc5 fixes this by using a header. It allows the merged mining info to be anywhere in the parent coinbase. It is backwards compatible with the previous version.
!v | Namecoin founder | https://dot-bit.org/

Luke-Jr
Posts: 13
Joined: Wed Aug 10, 2011 3:33 am
os: linux

Re: Testnet Merged Mining Block Number

Post by Luke-Jr »

Ok, as much as it annoys me to sign up for stupid forums for a one-off discussion, implicitly relaying stuff through doublec is slow etc. And despite not really caring much about namecoin, I can't seem to resist the urge to make sure this gets done right... :p

Problems with this "header" approach:
1) It takes up extra space in the coinbase -- we only have 100 bytes, each merkle takes up 33; that gives us room for 3 aux chains at most. Adding 4 more bytes for a header kills any hope of ever doing 3 aux chains. (in fact, it would be nice if the space requirements were reduced...)
2) Since the code only allows the header once, you can't have two aux chains.
3) The header can occur accidentally in other coinbase data.

Why is it so hard to simply disallow a master-chain block from "vouching for" more than one block in each aux chain? :/

nodemaster
Posts: 172
Joined: Wed Jun 15, 2011 12:46 pm
os: linux

Re: Testnet Merged Mining Block Number

Post by nodemaster »

Thank you four your feedback. it is much appreciated!
Luke-Jr wrote: 1) It takes up extra space in the coinbase -- we only have 100 bytes, each merkle takes up 33; that gives us room for 3 aux chains at most. Adding 4 more bytes for a header kills any hope of ever doing 3 aux chains. (in fact, it would be nice if the space requirements were reduced...)
Yeah, that sounds reasonable. In fact I guess it would be desirable to even support more AUX chains
Luke-Jr wrote:2) Since the code only allows the header once, you can't have two aux chains.
I would really like to see more than one blockchain supported. There are a couple of blockchains in the make and IMHO it won't make sense to only support BTC and NMC.
Luke-Jr wrote:3) The header can occur accidentally in other coinbase data.
I'm not a C programmer, but I understand that this could lead to unwanted problems. Any idea on how to find a "coinbase proof header"?
Luke-Jr wrote:Why is it so hard to simply disallow a master-chain block from "vouching for" more than one block in each aux chain? :/
Mhmm, If I understand it correctly this might be undesirable because it might be (and is common) that you solve several AUX chain blocks and have one master-block vouching for them, right? This problem would only be solved if the difficulty of both blockchains draw levels.
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vinced
Posts: 63
Joined: Wed May 18, 2011 1:16 am

Re: Testnet Merged Mining Block Number

Post by vinced »

Luke-Jr wrote:...
Problems with this "header" approach:
1) It takes up extra space in the coinbase -- we only have 100 bytes, each merkle takes up 33; that gives us room for 3 aux chains at most. Adding 4 more bytes for a header kills any hope of ever doing 3 aux chains. (in fact, it would be nice if the space requirements were reduced...)
2) Since the code only allows the header once, you can't have two aux chains.
3) The header can occur accidentally in other coinbase data.

Why is it so hard to simply disallow a master-chain block from "vouching for" more than one block in each aux chain? :/
These concerned have already been addressed in the current code. The aux chain merkle root is stored in the parent coinbase. You can have any number of aux chains under that root with no growth in the parent coinbase.

The chance of accidental appearance of the header in coinbase data is too small to worry about - 2^-32.
!v | Namecoin founder | https://dot-bit.org/

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