Gold collapsing. Bitcoin UP.

[cypherdoc]

And the hits keep coming for the dangerous experiment of maintaining artificially constrained blocks. From 2009-14 Bitcoin functioned with no effective block size limit and mining decentralization post-ASIC was improving. Now, in 2015, that this latent piece of software is allowed to take effect the unintended consequences rear up:
(my bold emphasis below)

(Updated:  I said 1/phi, I should have said 1 - 1/phi.  The attack works for any miners who controls more than 38% of hashing)

The so-called "stress test" was successful.  The attack it was testing is underway.  

Any miner who cotrols more than one minus 1/phi of the mining power, makes a profit while paying the fees it takes to maintain a permanent backlog of transactions, for as long as the blocks are more than half full of other transactions.

The mining-expenses market is unstable when there are enough legitimate transactions to fill more than half a block, because such a miner will reap more per yuan invested in mining power than any other miner.  This leads to a monopoly.

Well, crap.  I have done the math now.  

I know exactly what's happening.  It's a Golden Ratio Attack.  This is serious.  It ends with a mining monopoly.

What we have now is no longer a test.  The test was apparently successful.  What we have here is the new business model that was being tested.  

This backlog will probably be sustained FOREVER, because the people doing it make a profit by doing so.

The following assumes expenses roughly equal for miners relative to the amount of hashing power they control.  This is not exactly true, because a miner someplace where electricity is subsidized (like China) has substantially lower expenses.  In such a place the fraction of mining power required to make it profitable would be even less.

The *initial* "stress test" was a test to see whether the miner controlled sufficient hashing power to make a profit by doing this.  We can assume that test was successful, because now this miner is doing it.  Probably permanently.

The miner decides how much they want per transaction (anything that the traffic will bear, as long as it keeps blocks more than half full of real transactions), then keeps the backlog sufficiently full with bogus transactions to prevent any tx that pay less than that from going through.

Maintaining the backlog subsidizes other people's mining as well as their own, but means they don't need to compete with miners willing to process transactions for less money in fees because those miners aren't willing to process transactions for less fees when any transactions with more fees are available.

Let's work the math.  If 2/3 of the transactions actually processed are "real", then whoever is maintaining the backlog is paying the tx fees for 1/3 of every block. If this is someone with half the mining power then they get half of their third back, so their average cost per block is the fees for 1/6 of the block.  If we are talking about someone with half the mining power, their average return per block is 1/2 the fees for a block.  Because 1/2 is greater than 1/3, they are making a profit.  

The breakeven point for the biggest miner was when his fraction of the mining power plus the fraction of each block devoted to legitimate transactions was equal to one.  We can conclude that whoever is doing this, if he started the instant it was profitable, controlled 1 - 2/(1 + sqrt(5)) of the mining power at that time.  This happens to be one minus the inverse of the Golden Ratio.

It will continue to be in the financial best interests of any miner controlling more than 1 - 2/(1 + sqrt(5)) of the mining power for as long as blocks are more than half full with legitimate transactions.  

This does not affect, and is not influenced by revenue from block subsidies AT ALL.

All miners will see increased fee revenues in the competitive market.  They will respond to more revenue by  investing more in equipment.  Those miners are still competing fairly with each other, though they will make less on their investment than whoever's maintaining the backlog.  It is not in their best interests to add bogus transactions to the queue because with a smaller fraction than 38% of the mining power they would lose money on the fees they invest.

But any miner for whom this IS profitable, will make additional revenue that the fair market among miners does not.  What percentage more, depends on what fraction of the hashing power he controls. Any such miner is competing at an advantage and will eventually drive all other miners out of the market.

Miners for whom this is profitable must control at least 38% of the mining power.  Therefore there can be no more than two miners doing it at a profit.  And it's got positive feedback, so those two cannot compete fairly. Assuming there are two, the instant one of them has more hashing power than the other, he has a competitive advantage over the other (gets back as revenue a greater fraction of all fees spent) than the other miner) and will eventually drive him out of the market.

hmmm, where did we hear this one before?:

Here are some attacks which are affected by the number of nodes and/or miners and/or hashrate:

Attacker: Miners
Attack: Double spending. A miner can spend bitcoins on a product or service, then produce a block which invalidates the spend
Probability of success: 100% when the hash rate of the attacker exceeds the hash rate of the rest of the network
Severity: Number of bitcoins controlled by the attacker * number of attacks performed

Attacker: Miners
Attack: Denial of service. A miner can engage in selective censorship of transactions
Probability of success: 100% when the hash rate of the attacker exceeds the hash rate of the rest of the network
Severity: % success rate of censor identifying transactions they wish to block * value of the blocked transactions

Attacker: Nodes
Attack: Double spending. An attacker can defraud a target who is using an SPV wallet by providing them with invalid block headers which allow the attacker to pay the target with a transaction which references non-existant inputs
Probability of success: 0% unless the attacker can prevent the target from communicating with any honest nodes
Severity:  Number of bitcoins controlled by the attacker * number of attacks performed

How about this one:

Current situation where blocks are getting full from artificial 1MB cap:
Attacker: large miners like f2pool
Attack: spam network from one of its wallets to another. Drive up overall fees of regular users.
Success: 100%

[cypherdoc]

as for another prediction, just to ram it home:

[–]cypherdoc2 9 points 1 year ago

I'll take the cautious side here being a stake holder in Bitcoin. Not being a dev my concerns are purely theoretical and mostly economic.

    In general, a for profit company with a low to no stake in Bitcoin should not be trusted to make changes to the protocol that facilitate its profit making. Especially if it's gone out and hired core devs and comes at the expense of the competition.
    I would like to know who these core devs are supposedly supporting the whole concept besides gmax who has gone on record saying Bitcoin needs to be "fixed". I don't understand the secrecy as I've asked for those names several times. I for one don't think Bitcoin needs fixing.
    I've always conceptualized Bitcoin as being a self contained financial system so I am concerned that it's fundamental value units will be allowed to leave its system destined for what will inevitably be a weaker sidechain from a security standpoint. In that sense I don't see them as "the first app" overlaying the protocol like Andreas likes to say. I see them as fundamentally integrated into the network. Invariably, whatever token your bitcoin is transformed into will be worth less as a result. We've spent 5 long years distributing those bitcoins throughout the blockchain in a fair and truthful manner based on free market trading. $600 million has been irreversibly spent to secure that process and the blockchain is delicately balanced as a result. Bitcoins are a fundamental value unit that was made for its network and only for that network in my opinion and now we want to let them move off that network potentially never to return. Satoshi never provisioned for this. That doesn't feel right to me.
    What knock on effects would occur to the Bitcoin network if 20-30% of these tokens get lost from a sidechain failure thus wiping out all the associated bitcoins as a result? The answer could be way more complex than just "oh, my bitcoins will be worth more".
    With merged mining it would be easier to attack and steal the tokens and thus bitcoins associated with them. What can be done to prevent this?
    What if there was an economic way to solve the problem of scamcoins without touching the protocol? I reference Peter R's proposal of Spin Offs. https://bitcointalk.org/index.php?topic=563925.0
    Is there really a "problem"with Bitcoin that we need to risk the entire system like this? Why can't Bitcoin act like a reserve currency around which altcoins can orbit without touching/risking the protocol? I reference the fork we got from a simple non protocol change last year from just 0.7-0.8. The devs including gmax failed to anticipate this despite the best of intentions.
    It's important to realize that we have intentionally lived with bugs in the system all these years because we're dealing with a form of money that you can't make mistakes with. Billions are at risk and damned straight I'm protective of this. Bitcoin has worked well so far imo. It seems we always get these proposals at the bottom of a price lull so be wary of people proposing changes who have no stake in the system.

I'm willing to wait until the whitepaper comes out for final judgment as maybe I'm getting too conservative in my old age but those are my concerns.

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https://www.reddit.com/r/Bitcoin/comments/23fr63/bitcoin_20_unleash_the_sidechains/cgwt2nz

[iCEBREAKER]

hmmm, where did we hear this one before?:

How about this one:

Current situation where blocks are getting full from artificial 1MB cap:
Attacker: large miners like f2pool
Attack: spam network from one of its wallets to another. Drive up overall fees of regular users.
Success: 100%

Wow, you totally anticipated Cryddit's Golden Ratio Attack.  Amazing.

And that why you are indisputably the LebRon Jones of Bitcoin!

/

[cypherdoc]

hmmm, where did we hear this one before?:

How about this one:

Current situation where blocks are getting full from artificial 1MB cap:
Attacker: large miners like f2pool
Attack: spam network from one of its wallets to another. Drive up overall fees of regular users.
Success: 100%

Wow, you totally anticipated Cryddit's Golden Ratio Attack.  Amazing.

And that why you are indisputably the LebRon Jones of Bitcoin!

/

why thank you iCEBlow!  i'm glad you recognize brilliance when you see it.  you may kiss my ass now.

[majamalu]

The block size limit is not a problem.



Kim Jong-iCE will know exactly when we need more space.

[iCEBREAKER]

I suspect we agree that should 1MB blocks become an undeniably urgent concern (EG, if we see actual congestion resulting in appropriate fees no longer prioritizing their tx) the controversy will rapidly dissipate and be replaced by emergent rough consensus.

Kim Jong-iCE will know exactly when we need more space.

The Democratic People’s Republic of Corea thanks you for recognizing my prescience and leadership in addressing this important matter.

[cypherdoc]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

[cypherdoc]

I suspect we agree that should 1MB blocks become an undeniably urgent concern (EG, if we see actual congestion resulting in appropriate fees no longer prioritizing their tx) the controversy will rapidly dissipate and be replaced by emergent rough consensus.

no, the eye doctor says you're a blind fool.

[iCEBREAKER]

I suspect we agree that should 1MB blocks become an undeniably urgent concern (EG, if we see actual congestion resulting in appropriate fees no longer prioritizing their tx) the controversy will rapidly dissipate and be replaced by emergent rough consensus.

no, the eye doctor says you're a blind fool.

Why do you say that?

Do you believe the controversy will *not* rapidly dissipate and be replaced by emergent rough consensus, should 1MB blocks become an undeniably urgent concern?

[cypherdoc]

I suspect we agree that should 1MB blocks become an undeniably urgent concern (EG, if we see actual congestion resulting in appropriate fees no longer prioritizing their tx) the controversy will rapidly dissipate and be replaced by emergent rough consensus.

no, the eye doctor says you're a blind fool.

Why do you say that?

Do you believe the controversy will *not* rapidly dissipate and be replaced by emergent rough consensus, should 1MB blocks become an undeniably urgent concern?

you and the other Cripplecoiner's are blind fools to what is happening right now as a result of the 1MB choke you are inflicting on Bitcoin.  you don't have the vision to determine when there is urgency.

[brg444]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

well someone was kind enough to spare us the effort to "rekt" your hypocritical "concern" on reddit :

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct4yc63

[cypherdoc]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

well someone was kind enough to spare us the effort to "rekt" your hypocritical "concern" on reddit :

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct4yc63

brg444 jumping to rektless conclusions again.  i actually have a response i have yet to use to eragmus. 

[brg444]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

well someone was kind enough to spare us the effort to "rekt" your hypocritical "concern" on reddit :

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct4yc63

brg444 jumping to rektless conclusions again.  i actually have a response i have yet to use to eragmus. 

And as expected, a wholly unoriginal reply rehashing tired and disingenuous arguments. See my reply 

[Peter R]

On the topic of "what is a conflict of interest," I think this explanation (from a high impact factor academic journal) is good:

Conflicts of interest

In the interests of transparency and to help editors and reviewers assess any potential bias, the journal requires authors of original research papers to declare any competing commercial interests in relation to the submitted work. It is difficult to specify a threshold at which a financial interest becomes significant, but as a practical guideline, we would suggest this to be any undeclared interest that could embarrass you were it to become publicly known. Referees and editors are also subject to Conflict of Interest regulations.

As an example, let's say I had a company (perhaps that was still in stealth mode) that performed the service, similar to what BlockCypher does, of calculating "confidence factors" for 0-confirm transactions.  

Now let's imagine I write an academic paper that presents data on double-spend statistics and shows how one can use network heuristics to reliably accept 0-confirm transactions for certain business models.  

What I present in the paper may be entirely factual and unbiased, but I still have a conflict of interest and I should declare that fact to the public.  A conflict of interest is not, in and of itself, a bad thing.  In fact, since we're imagining I'm in the business, I'm probably pretty knowledgeable on the topic!  Nonetheless, I should still be transparent and allow others to assess the results and any biases I may have for themselves.  

[brg444]

On the topic of "what is a conflict of interest," I think this explanation (from a high impact factor academic journal) is good:

Conflicts of interest

In the interests of transparency and to help editors and reviewers assess any potential bias, the journal requires authors of original research papers to declare any competing commercial interests in relation to the submitted work. It is difficult to specify a threshold at which a financial interest becomes significant, but as a practical guideline, we would suggest this to be any undeclared interest that could embarrass you were it to become publicly known. Referees and editors are also subject to Conflict of Interest regulations.

As an example, let's say I had a company (perhaps that was still in stealth mode) that performed the service, similar to what BlockCypher does, of calculating "confidence factors" for 0-confirm transactions.  

Now let's imagine I write an academic paper that presents data on double-spend statistics and shows how one can use network heuristics to reliably accept 0-confirm transactions for certain business models.  

What I present in the paper may be entirely factual and unbiased, but I still have a conflict of interest and I should declare that fact to the public.  A conflict of interest is not, in and of itself, a bad thing.  In fact, since we're imagining I'm in the business, I'm probably pretty knowledgeable on the topic!  Nonetheless, I should still be transparent and allow others to assess the results and any biases I may have for themselves.  

Granted.

A bad thing is when people like cypherdoc derive from the conflict of interest malicious intents without proof other than "I don't trust them"

[cypherdoc]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

well someone was kind enough to spare us the effort to "rekt" your hypocritical "concern" on reddit :

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct4yc63

brg444 jumping to rektless conclusions again.  i actually have a response i have yet to use to eragmus. 

And as expected, a wholly unoriginal reply rehashing tired and disingenuous arguments. See my reply 

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct505jf

[Peter R]

Granted.

A bad thing is when people ... derive from the conflict of interest malicious intents without proof other than "I don't trust them"

Right.  There's two things to consider:

(1) Does someone have a conflict of interest?

(2) Is that person acting upon his conflict of interest or is his opinion biased by his conflict of interest?

Granted, we don't know to what extent (2) holds for anyone at Blockstream.  But the answer to (1) is clearly "yes."  Would you agree?

[cypherdoc]

On the topic of "what is a conflict of interest," I think this explanation (from a high impact factor academic journal) is good:

Conflicts of interest

In the interests of transparency and to help editors and reviewers assess any potential bias, the journal requires authors of original research papers to declare any competing commercial interests in relation to the submitted work. It is difficult to specify a threshold at which a financial interest becomes significant, but as a practical guideline, we would suggest this to be any undeclared interest that could embarrass you were it to become publicly known. Referees and editors are also subject to Conflict of Interest regulations.

As an example, let's say I had a company (perhaps that was still in stealth mode) that performed the service, similar to what BlockCypher does, of calculating "confidence factors" for 0-confirm transactions.  

Now let's imagine I write an academic paper that presents data on double-spend statistics and shows how one can use network heuristics to reliably accept 0-confirm transactions for certain business models.  

What I present in the paper may be entirely factual and unbiased, but I still have a conflict of interest and I should declare that fact to the public.  A conflict of interest is not, in and of itself, a bad thing.  In fact, since we're imagining I'm in the business, I'm probably pretty knowledgeable on the topic!  Nonetheless, I should still be transparent and allow others to assess the results and any biases I may have for themselves.  

Granted.

A bad thing is when people like cypherdoc derive from the conflict of interest malicious intents without proof other than "I don't trust them"

except that:

1.  i predicted something like this block size conflict would come up as a general concept; them preventing upgrades that would help Bitcoin.  and...

2.  they won't even acknowledge there's a conflict of interest.  in fact, they spend all their time around here denying it.

[brg444]

conflict of interest

n. a situation in which a person has a duty to more than one person or organization, but cannot do justice to the actual or potentially adverse interests of both parties. This includes when an individual's personal interests or concerns are inconsistent with the best for a customer, or when a public official's personal interests are contrary to his/her loyalty to public business. An attorney, an accountant, a business adviser or realtor cannot represent two parties in a dispute and must avoid even the appearance of conflict. He/she may not join with a client in business without making full disclosure of his/her potential conflicts, he/she must avoid commingling funds with the client, and never, never take a position adverse to the customer.

well someone was kind enough to spare us the effort to "rekt" your hypocritical "concern" on reddit :

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct4yc63

brg444 jumping to rektless conclusions again.  i actually have a response i have yet to use to eragmus. 

And as expected, a wholly unoriginal reply rehashing tired and disingenuous arguments. See my reply 

https://www.reddit.com/r/Bitcoin/comments/3dg1us/the_golden_ratio_attack_blocks_more_than_half/ct505jf

So this boils down to you trusting MIT more than Silicon Valley.

If only Aaron Swartz was here to answer this one.

[justusranvier]

A bad thing is when people like cypherdoc derive from the conflict of interest malicious intents without proof other than "I don't trust them"

What actually happened is that when Blockstream was announced multiple noted that it created the appearance of a potential conflict of interest.

Instead of acknowledging this potential (fairly standard practice in many business situations!), the Blockstream founders took the bizarre route of denying even the possibility of a conflict of interest.

That choice of actions is what lead to ongoing concern about their motives, not the founding of Blockstream itself.