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https://github.com/bitcoinclassic/bitcoinclassic/pull/152


https://i.imgur.com/AXhXNts.png
https://i.imgur.com/pvmqAmx.png

it's disgusting. he used to care about what was good for the bitcoin network. now he backtracks on everything he said, so Classic can take over the bitcoin protocol.

even if we assume that most people want a block size increase, wtf is this? now slipping things into Classic that everyone knows is bad for the ecosystem, and which users dont want? he's trying to buy miner votes for Classic with this PR, against all of our interests as users!

this really endangers lite nodes that depend on miners fully validating! people always say full node counts drop because people are moving to lite nodes. and if blocks get bigger, even more. that just means all the more people are going to lose money when miners build on top of invalid chains.

if this gets adopted, and you run a lite/SPV/api node wallet (electrum, multibit, blockchain.info etc) make sure you wait for additional confirmations (6+)! 0-2+ confirmation transactions will be much less safe for anyone that does not run a full node.

Not surprising. These are very, very dark days for Gavin. This move comes off as quite desperate. The community has been well aware of the dangers of SPV mining at least since early last summer. Hard coding it into the software so that harmful practices used by some miners are now participated in by all miners is just.....omg......especially when he has publicly stated that these are harmful practices.

Absolutely true.  Assuming that those 0-2+ confirmations all come within 30 seconds...

https://github.com/bitcoinclassic/bitcoinclassic/pull/152

So, I definitely agree with trashman43. You should absolutely wait for more than your usual number of confirmations (unless 30 seconds have already passed since you received the payment, in which case it looks like it may be ok to just go with whatever your usual number of required confirmations is).

Wow. I used to respect Classic, I thought they were a great alternative to Core if I ever was going to change. Because of this, I might as well move to electrum ::)

you do realise that making "empty blocks" is not about making the average 10 minute block empty.
its about giving somthing to ASICS to work on during the minute or 2 that the pool server is validating a competitors previous block solution. and then when validated, the pool server sends the next cluster of unconfirmed transaction hash to the asics to fill the empty block with data.

its just by pure luck that some of the blocks are solved in a couple minutes and it has become visible.
which if blocks were solved in more then 2 minutes no one would know the difference..

the only issue is that sometimes the asics get lucky and have a solution in under 2 minutes before they get a chance to handle real data. which again is just luck. so chill out

atleast its better then making all the pools wait 2 minutes before doing anything, which would bring the average solution to more than 10 minutes and causing the difficulty to drop.

which if a pool server has to validate segwit+payment codes means pools are taking even longer to validate, causing again blocks to take longer until there is a viable solution. which again reduces the difficulty.

now imagine this:

if we had all pools waiting 4-8 minutes before actually hashing. with a lower difficulty. it only takes 1 pool with less hashpower to do an empty block to get a quick solution because they have a 4-8 minute headstart against the competitors.. which is another vector of the 51% attack theorum..

also add to the mix that a malicious pool sends out false blocks to waste competitors time making then validate a block for 2 minutes because they know by sending out false blocks delays the ethical competitors by 1-2 minutes per false block, ths a malicious pool can endlessly keep doing it for hours... sending  false blocks every 30 seconds so that competitors never even get to hash anything..  causing ethical miners to waste many many minutes validating and ultimately rejecting the false flag blocks, giving the malicious pool more of a head start.

its better that all pools follow the same rules where no one has an advantage by not leaving themselves open to abuse using delays... rather than hoping everyone delays their own efforts leaving a risk for abuse..on the pure hope and blind faith that no one malicious would try.

also remember.. hashing an empty block does NOT mean it will get solved in 1-2 minutes.. its just that sometimes they get lucky before they had a chance to fill blocks

id rather have 20 pools that occassionally got lucky then 20 pools that get delayed by 2minutes-2 hours due to a malicious attack vulnerability. and have only 1 pool solving blocks with malicious intent

A couple thoughts on that, since it sounds like you are possibly being sarcastic.


I'm not sure of the math when we change the time period from 60 seconds to 30 seconds, but you get my point, right? This is particularly problematic for automated systems (although one would be pretty foolish to build an automated transaction system that does not fully validate).

The trouble with assuming that everything is fine because of the 30-second window.... if this vulnerability is consistent then an attacker only needs to wait, mining with low hashrate, for a block to happen. Luke describes how attacks could be mounted:



That's not what the issue is, although I do think that Classic users find the practice upsetting when they realize it's happening.

Hmm. Not sure about that.

https://www.reddit.com/r/Bitcoin/comments/4apl97/gavins_head_first_mining_thoughts/d13nv7p

https://www.reddit.com/r/Bitcoin/comments/4apl97/gavins_head_first_mining_thoughts/d12op9j

Now, if miners stop using that code --- and nothing in the node software can force them to do that AFAIK --- what kind of trade-off are we making? What are the risks?

Theoretically this would make attacks by a malicious pool more likely, to make attacks based on SPV-mining vulnerability less likely. That trade-off is only necessary because SPV-mining would be hard-coded into the software that all miners run, rather than a bad practice used by some miners --- and making the practice ubiquitous simply exacerbates the dangers that SPV-mining already poses. In other words, Gavin is hard-coding changes that improve orphan risk for miners at the direct cost of user security.

Is that really the best choice? And if so, let's get some more numbers and risk simulations rather than the usual on bitcointalk/reddit, which is to take Gavin's word that every change is both warranted and safe.

Why, I remember something like a year ago, Gavin made it seem like the world would end if we didn't increase the block size immediately. That simple fact should make everyone weary of his judgment and expertise, particularly when hard-coding bad miner practices into the protocol.

Side note: Wasn't Classic being passed off as nothing but a bump to 2MB, because of the controversial changes that were coded into XT? What else is Gavin planning on slipping in?

I agree with you, I don't blame Gavin, I see he realized how SPV mining actually is not that terrible for the network as evident from the start.

what else is luke Jr planning on slipping into core..
what else is Sipa planning on slipping into core..

its a bit of tit-for-tat

Luke and Sipa are not releasing a contentious hard fork. Gavin is.

And Classic is presenting that hard fork as "a one-feature patch to bitcoin-core that increases the blocksize limit to 2 MB." Is that really the case?

See https://bitcoinclassic.com/

Says it right on the front page. Further, Luke and Sipa can't just slip anything into Core anyway. Not at all. Core has a drawn-out code review process that prevents anything like that. Classic has only a few developers and no peer review. Big difference.

luke is proposing a hard fork.. to mess with the difficulty purely so his eligius pool can survive a few more weeks after the reward halving..
it might be worth to investigate blockstream just as much as any other bitcoin development group.

by the way there are 12 groups.. not two. so feel free to expand your mind, and to be less blindly faithful to one team

Don't confuse things: I am faithful to the protocol's consensus mechanism, NOT "a team." Core happens to be the only "team" that respects consensus in this debate.

Regarding this alleged hard fork, link to the BIP? I'm fairly sure you're mischaracterizing, as usual.

No comments on the fact that Classic is selling itself as "a one-feature patch to bitcoin-core that increases the blocksize limit to 2 MB"....when things like SPV mining are being coded into the software? Seems pretty shady.

blockstream just as shady.
did you know that a segwit+confidential payment codes while sticking to the 1mb maxblocksize limit actually has a real data value of 2.85mb thanks to the twisting of data. and allows for only a potential 3800 transactions.
whilst a simple 2mb maxblocksize allows a potential 4000tx for 2mb.

oh and here is a link to luke Jr wanting to throw in a difficulty twisting hard for with only a 3 month grace period (#GracePeriodHypocracy)
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-March/012489.html

enjoy.
it seems instead of thinking of a community effort where blockstream adds in the 2mb buffer to protect the community against possible consensus. you believe that blindly following them that delaying any release of code is good. that is not consensus, that is causing contention.

basically by not supplying the code they are the cause of the contention that they scream would be the result of no consensus.. yet if they release the code then everyone can have it and then there is no contention.

stop blindly following blockstream. put on your unbiased hat and think about the community as a whole not your favouritism towards one corporation.

there is no 2mb classic vs segwit blockstream debate.
there is only "when will 2mb+segwit be active" debate. (both features working together)

Actually there is no 2mb anymore: If the 2mb is accepted then you automatically go for a ...dynamic blocksize. The 2mb is just to lure in the trojan horse of dynamic blocksizes.

https://github.com/bitcoinclassic/documentation/blob/master/roadmap/roadmap2016.md

Phase 3 (Q3-Q4)

Make the block size limit dynamic

Note: This phase will only happen when miners & companies confirm Phase 2 successfully addressed their blocksize concerns.

Hmm... why would the chosen quote begin mid-sentence.  You conveniently cut the "It starts with" from that sentence.  Could it be that the entire paragraph goes a bit differently?


Gee. It sounds to me like they're doing exactly what they said they were going to do.

That doesn't support anything you said. :D


Are you not aware of the Hardfork Wishlist (https://en.bitcoin.it/wiki/Hardfork_Wishlist)? It's been around since at least January 2012. The premise is that if bitcoin ever needs to hard fork, these are desired improvements that can only be implemented with a hard fork and therefore should be included. Luke's proposal has been on the Wishlist since at least January 2012. It's always been considered a bug to be fixed when possible. And he speaks of including it in a future proposed hard fork -- not a hard fork for the sake of implementing that bug fix alone --  as would be expected. The concept isn't controversial in the slightest (assuming sufficient testing). But feel free to explain how it is.

Also, you misunderstood regarding 3 months. He said it could be rolled into anything proposed around that time, because the code should be ready by then. He says nothing about the time period between consensus on rule activation and fork in regards to this proposal, though he is known to be conservative in that regard.

Your assumptions about Luke's proposal were also shown to be false: https://bitcointalk.org/index.php?topic=1387549.0;all

lol read more. he wants the code available in april. to be activated at the turn of the block 420,000 (when the reward halves) so that miners do not lose out instantly.

have a nice day

I left it out because Classic hasn't increased the blocksize limit to 2 MB. If they had, it would have forked already.

So yes, it is dishonest to say "it starts with" when that isn't true. It actually "starts with" other "features" (like hard-coded SPV mining) that have absolutely nothing to do with increasing the block size.

More importantly, there is really no question that Classic has been marketed by everyone involved as increasing the block size -- there has been virtually no discussion of anything else at all. Just as Bitcoin XT was. Do you recall how XT similarly had "features" coded into it that the community did not support?


Um, source?

https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-March/012492.html

He also clarified the very same day regarding the link you posted:


So either you need to "read more" or you're just being dishonest here.

On that note, Paul Sztorc has some enlightening thoughts on why having such code ready is very important:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-March/012501.html

An emergency hard fork (as in 2013) is just that. There is no plan to activate this rule at halving, and Luke is not suggesting that. So stop spreading misinformation, please. And that fail of a quip you just made doesn't change the fact that your own thread shows that all of your assumptions about why the proposal is bad, were wrong.

Have a nice day

Jeez how much longer until Classic is finally confined to the garbage bin? How & why are some of the community still pushing this crap & backing Gavin?

most are not backing gavin. most see the bigger picture that there cannot be only one implementation and that all implementations should have the same basic rules and have enough buffer to allow for growth and be able to cope with change. no matter who its by or for what purpose without having to cry to a dev leader for more buffer space

its never been about a power grab of gavin vs back. nor should it.
bitcoins vision is no one is in power. yet the doomsday scenarios of trying to say any coder thats not on blockstream payroll is bad.. is ultimately on the power play that only blockstream should rule.

my personal opinion is that 2mb+segwit should be the goal. and pools not leave themselves vulnerable by not hashing solutions while they validate a possible competitor solution. because not hashing can leave them at risk of receiving an endless download of fake blocks to cause pools to never mine a block due to endlessly validating fake blocks

This is precisely why we need *viable* altcoins. They would bring balance of power.

Users like us would use the coins that are in our best interest and miners would mine those coins because they would be the only coins with a block reward worth mining.

Validating a block takes around 300ms on my pool.
My pool has the 2nd highest average block size.

The highest is solo.ckpool.org that also has this tiny time to validate blocks.

So anyone using some argument about why empty blocks are required clearly has no idea about the facts and about coding.

The pro empty block argument is FUD to cover crappy pool software and low quality coders.

I don't think this is good at all... I guess we didn't learn much from the last time we forked after a little chaos (https://www.reddit.com/r/Bitcoin/comments/3c305f/if_you_are_using_any_wallet_other_than_bitcoin/csrsrf9) in SPV mining and BIP66 activation.

maybe worth you telling that to Lauda, to debunk his validation time doomsday scenario of larger blocks

I think that the problem for china pools/miners is related to "download blocks", and not validate them.

Head first mining (that it isn't SPV mining), will work great with this too:
https://github.com/bitcoinclassic/bitcoinclassic/pull/147

Classic is a Trojan horse filled with allied Buttcoiners and CoinbaseCoiners.

The Buttcoiners failed to get Honey Badger's attention with their futile (albeit occasionally amusing) ass-clowning, so they're trying a new angle.

By pretending to be actual Bitcoiners, the media and other low-information institutions/individuals are more apt to take them seriously.

We can do the same thing back to them by feigning support for "Satoshi's Bitcoin" (a project that is not compatible with Classic's goals because it eventually changes the PoW).

Time to update the Classic #REKT thread with this latest hilarity from the Gavinista LOLcows!   ;D

mining POOL servers do not need to be in the same physical location as the ASIC warehouse..

antpool for instance is in sanfransisco. while the warehouse of ASICS that just does the hashing element is in china, a short distance from the manufacturer. this avoids any delay in time for delivery and costs.

remember the pools processes the transactions/validates blocks. and the ASICS just hash away a small clump of data. the asics do not relay transactions (they are not nodes) they do not receive competitors blocks(syncing the chain). basically they have no hard drive and only have one job.. to hash.

so an asic behind the china firewall does not care, and the pool owner can have the pool server anywhere in the world, still connected to his asics in china

Everyone has to download blocks to mine ... unless they are SPV mining.

The term "Head first" has nothing to do with mining, unless you are SPV mining.

SPV mining means mining off the header without validating the transactions the header confirms.
You can't just use the header to mine unless you are SPV mining.

Thus the term "Head first mining" makes no sense at all since it is simply SPV mining -
and thus no need to create a new name to hide that fact.

"SPV mining" was that the miner/pool was starting mining on the header without knowing if it was already validated.

Miners/pools were just guessing/hoping that it was right only because the interrogated pool was changing to a new header.

With "Head first mining" nodes spread validated header (because they validate the block after fully downloaded it)

They are mining without validating blocks first. That's called SPV mining.

LOL..... you guys really trying to defend this bullshit? Gavin has gone off the deep end, and more and more people are realizing it. I'm all for improving on orphan risks. But not by jeopardizing user security. If it's not obvious to everyone why he is proposing this now then you aren't thinking hard enough. He's trying to buy off Chinese miners at the cost of our security.

Every action that Gavin takes further solidifies my choice to run a Core node and ignore miners that attempt to hard fork. Fork off, I don't give a shit anymore. Go ahead and break bitcoin's consensus. Scumbags like Gavin don't give a fuck about us, the users.

To be honest I was way more bearish last year about Bitcoin but seeing it successfully defend itself against the Gavinistas has given me hope.  The community sees through these attacks now, including spv mining is such an obviously bad idea that I hope some of the Gavinistas finally see the light.

Minor correction. 300ms is the slowest block validation time. Some blocks are much faster to verify depending on how complex it is. Solo has different hardware and verifies in up to ~140ms by comparison.

Well, did Gavin and Mike Hearn not try something similar with the XT implimentation? Sneaking in code to spy on people and blacklisting IP's was just one of the things they tried. This is one of the reason I am not supporting the Classic/Gavin fanboys. They hook you in the beginning by providing all the features people think they need and once they are in control, they will sneak in more things you do not want. A small tweak here and there. Do not give these guys the foot in the door, they will destroy Bitcoin.

I guess you are trying to imply that someone else has validated the transactions.

Well, that makes no difference since someone somewhere along the way has to validate it, and unless you control what validates it, you are SPV mining.

If you control what validates it, well, you are still having to wait for it to be validated, so yeah there's no sense in implying there's a performance gain unless you really are SPV mining and not validating it somewhere.

What I proposed to the devs was to allow a trust relationship to pass SPV headers to other btcd - to fully validate the header, excluding the contents of the merkle tree, is only nanoseconds.
Since all btcd SHOULD be validating the transactions (and core does this) it means of course you still need to validate them, but you don't have to wait for everyone you are connected to, to validate them also, i.e. allowing to choose to remove the largest repeated work before forwarding the block.

This is called "Black Magic" by gmaxwell:
"In general our experience suggests that trust settings are black magic that cannot be configured correctly even by experts"
https://github.com/bitcoin/bitcoin/issues/7049

@exstasie @kano
Both header and POW are shared on the network (on head first mining (https://github.com/bitcoinclassic/bitcoinclassic/pull/152/files#diff-c2c990fee1c3381462640e80ae7db0d0R323)), so the miner/pool can check if it's valid or not, in few ms.

In SPV mining the miner/pool only receive the header and NOT the POW.

There can be a situation where a miner/pool can create an invalid block (with invalid tx), but to make it, he will still need to make a valid POW.
It means that the miner/pool will have to pay the same costs to find an invalid block as finding a valid one.

And ... the invalid block will live only for 30 seconds at best.

The core rule of Bitcoin is more economic than technical, better financial results comes from working on the long interest of the network. (making invalid blocks is useless and uneconomic)

That may be your definition of SPV mining but the important fact about Gavin's code is that miners are not validating transactions.


And? Are you suggesting that the benefits of double spending will never outweigh the costs in that case? That seems very silly. Do you realize that after the next reward halving, the reward vs. risk for miners to double spend doubles? And that this is true of every halving? Security from dishonest miners becomes increasingly important as time goes on.


Read up thread. That's apparently not true and there is nothing the stock node software can do about it.


On its face, no it's not. It depends how much an attacker will gain by doing so.

Gavin I believe is doing what he thinks is best for Bitcoin. I just think he is wrong.

Hearn I have no respect for whatsoever.

It's not a problem. (https://bitslog.wordpress.com/2016/01/08/spv-mining-is-the-solution-not-the-problem/)

nothing in this blog addresses the security concerns presented here. no mention of gains in mounting double spend attack vs cost to produce invalid blocks based on spv vulnerability. the 20 second window mentioned cannot be enforced at the node level, so anyone following non-validating miners is at risk of being on a bad chain. and not just for 20 seconds.

that blog is totally useless

dont worry guys!

gavin says we dont need to plan against double spend attacks because it costs miners a whole block to attack someone! ::)

also, core supposedly has "zero clue what real-world security entails" -- coming from someone that says the whole network should assume that people are honest. thats the point of bitcoin right? to trust everyone else to be honest?

what a douchebag:

https://i.imgur.com/OGroWoW.png

this kind of mindset will be the end of bitcoin. security first, always. if people blindly follow gavin's best-case scenario planning, all hes gonna say when shit hits the fan is "oops! bitcoin is an experiment after all!"

Yep ... so much fail flying around these days, there's bound to be an accident.

headers only mining is dangerous and could result in loss of many blocks, if any one of the "headers only" blocks turns out to be fake null headers
or orphaned later

but it's good enough for now :)

The thing Luke pointed out is an extremely major issue, so it'd be crazy for anyone to use this until that behavior of mining software has been changed.

If that's addressed, then something like this change would make confirmations somewhat less reliable for lightweight wallets. You'd probably want several (3-6) extra confirmations to get the same level of security as before. However, the benefit is that it might be less of a problem for blocks to propagate slowly across the network. (Currently, if blocks take too long to propagate then it can cause orphan blocks for miners, and in severe cases protracted chain forks can result.) I'm not sure exactly how much benefit headers-first would actually bring, though. I guess maybe the benefit could be large enough to safely allow for larger block sizes, but my instinct is that the maximum benefit wouldn't actually be very large. More thought and measurements would be necessary.

If this was rolled out generally, several precautions would be necessary to ensure that a whole bunch of miners don't accidentally mine many blocks on top of an invalid chain. Furthermore, there's a nightmare scenario where the majority of miners mine on an invalid chain and never stop mining on it until manually fixed. Something like headers-first mining would have to ensure that these things are impossible, or that they could cause only small, limited damage.

Headers-first seems to me like mainly an improvement over the headers-only or validationless mining that some miners seem to be doing now, but not something ideal. I think that IBLT / weak blocks will be the real eventual solution to this problem.

if you are going to do that you might as well make block times more reasonable around 1 minutes,  dump 99.999% of the PoW and make it efficient, return mining to CPU only, etc...  a simple XOR checksum would do, etc, etc...