How a floating blocksize limit inevitably leads towards centralization

[Technomage]

Already controversy is brewing... Already businesses are starting to back away from bitcoin because if the block limit isn't raised then one of three things will happen: 1. Bitcoin fails. 2. Bitcoin gets used only for moving large amounts of money and other cryptocurrencies take over eventually displacing bitcoin itself. 3. Bitcoin gets used for only moving large amounts of money and "bitcoin clearing houses" fill the gaps, which increase the risk of fraud/theft/unaccountability, add avenues of attack, and form REAL centralization. Not some hypothetical BS.

Indeed. The centralization that comes from off-the-chain transactions is exactly the kind of centralization that our current world financial structure is based on. It will, for example, allow widespread use of fractional reserve banking, which is not possible with Bitcoin right now. Whatever happens, we must strive to keep most transactions in the blockchain (most, not necessarily all), otherwise the whole idea behind Bitcoin is more or less doomed.

[cjp]

Indeed. The centralization that comes from off-the-chain transactions is exactly the kind of centralization that our current world financial structure is based on. It will, for example, allow widespread use of fractional reserve banking, which is not possible with Bitcoin right now. Whatever happens, we must strive to keep most transactions in the blockchain (most, not necessarily all), otherwise the whole idea behind Bitcoin is more or less doomed.

Off-the-chain transactions are not necessarily centralized, although centralized solutions are definitely the most simple type, and will the first type to be available.
There are decentralized "off-the-chain" transaction systems. As mentioned before, it is possible with alternative block chains. Another decentralized off-the-chain transaction system is the one I proposed in this thread:
https://bitcointalk.org/index.php?topic=94674.0

I like it because it is mostly off-blockchain, and, unlike most Ripple systems, it does not allow fractional banking and requires only a minimum amount of trust (less trust than needed e.g. to trade goods or fiat currency online with Bitcoin). OTOH it is "unproven technology" and it will take some time to develop. I'll work on it as fast as I can in my spare time, so that I can demonstrate a prototype ASAP. I hope you see the importance of such systems.

[MoonShadow]

Whatever happens, we must strive to keep most transactions in the blockchain (most, not necessarily all), otherwise the whole idea behind Bitcoin is more or less doomed.

I disagree with this assumption.  It is entirely within reason for 'bitcoin clearinghouses' to exist that process the majority of out-of-band transactions, while remaining functionally decentralized.  The most important part is that it remains forever possible for anyone with the resources to jump onto the network and compete.  It does not have to be a cheap endeavor. 

That said, I would say that it would be wise endeavor that the main network is capable of processing enough transactions that it's unlikley that any single out-of-band processor can capture more than 50% of all transactions.  Practially, I don't think that this is a real worry unless Bitcoin never really becomes a global currency; for it's unlikely that users in China or Russia are going to favor a processing agency in the United States for their mostly local and mostly daily purchasing needs.  Thus, whichever processor grows up to be the Bitcoin version of Paypal in the United States is at a disadvantage towards capturing the Chinese or Russian markets due to cultural differences and simply mistrust of Americans.

In this context, such distrust is both well founded and advantageous to limiting centralization.

Furthermore, it's important that competition to any of the market dominators in the out-of-band transaction processing never be 'locked-out' from access to the main bitcoin chain nor (hopefully) co-opted by government policy.  The real problem is that we can't predict how these things are going to go with any real certainty.  What we can predict is how large of a block must be possible to sustain a particular transaction rate at the current average transaction size.  Personally, I consider the rate that Paypal can process transactions to be a practical minimum for consideration of a hard code fork, so nothing less than a 10MB hard limit is worth the trouble.  Fortunately, we are still years away from this problem, and have plenty of time to hash out the details.  In the meantime, we can just agree to raise the soft limit, or agree to simply let the rest of the miners to comment it out at their own desires.  Even the occasional full block isn't really a problem, so long as we don't have full blocks for hours on end.

[cjp]

• The block size limit is sufficiently high to allow "large" personal transactions (e.g. >$1000) to take place with acceptable fee levels.

Correct me if I'm wrong (unsure) but the bitcoin network doesn't "care" how much money you are moving. What it cares about are the amount of inputs. So it's possible to have a large amount of money with fewer inputs.. and a small amount of money with more inputs. So these "acceptable levels" are going to be for small transactions too. Which would as I said earlier...... means that bitcoin will probably fail with a hard low limit. Because if you are designing the network to have acceptable fee levels for 1k then it will also apply to smaller transactions. And those transactions and people will seek a new cryptocurrency.

It's true that the Bitcoin protocol has no knowledge about the exchange rate against fiat currencies (and it shouldn't). I mentioned $1000 more like a rough estimate about the amount of value we should aim for. If Bitcoin grows to complete use by 1e9 people, there would be 0.021BTC/person. If current dollar amounts are available to the USD-using population at $30000/person, the equivalent value would be 1.4e6 USD/BTC, so my $1000 would be about 0.0007 BTC. If you say that 10% fees are the maximum to be called "reasonable", transaction fee would have to be at most 70e-6 BTC. But, as you see, this number heavily depends on the number of people using Bitcoin. Since currently the effective(*) number of Bitcoin users is much lower, we can make much smaller transactions with an acceptable fee rate.

So, the fee level needed for this requirement will change over time, because of the changing value of Bitcoin. I don't think you can adapt for this in the protocol, but you can choose appropriate values in the protocol in order to meet this requirement in a wide range of Bitcoin prices and popularity.

(*) I expect that currently most Bitcoin users only use Bitcoin for a small percentage of their finances.

[jgarzik]

Already controversy is brewing... Already businesses are starting to back away from bitcoin because if the block limit isn't raised then one of three things will happen: 1. Bitcoin fails. 2. Bitcoin gets used only for moving large amounts of money and other cryptocurrencies take over eventually displacing bitcoin itself. 3. Bitcoin gets used for only moving large amounts of money and "bitcoin clearing houses" fill the gaps, which increase the risk of fraud/theft/unaccountability, add avenues of attack, and form REAL centralization. Not some hypothetical BS.

"already controversy is brewing"  Wonderful zero-evidence hypothetical BS handwaving there.  Yes, controversy is brewing... among those teenagers clueless about bitcoin and economics.

Bitcoin value and press reports indicate new bitcoin users and businesses every day.  The exact opposite of "back away"

[justusranvier]

Already controversy is brewing... Already businesses are starting to back away from bitcoin because if the block limit isn't raised then one of three things will happen: 1. Bitcoin fails. 2. Bitcoin gets used only for moving large amounts of money and other cryptocurrencies take over eventually displacing bitcoin itself. 3. Bitcoin gets used for only moving large amounts of money and "bitcoin clearing houses" fill the gaps, which increase the risk of fraud/theft/unaccountability, add avenues of attack, and form REAL centralization. Not some hypothetical BS.

"already controversy is brewing"  Wonderful zero-evidence hypothetical BS handwaving there.

Not quite zero evidence:

https://bitcointalk.org/index.php?topic=145498.msg1543934#msg1543934

[markm]

Mining is likely to remain decentralized to a high degree, to avoid a "single point of control"[/li][/list]

That is the only condition which changes between your conditions for adaptive block size and your conditions for a new constant hard limit.

Why is that? Do you feel that it is a foregone conclusion that an autoadaptive block size precludes fulfillment of such a requirement?

-MarkM-

[notig]

Already controversy is brewing... Already businesses are starting to back away from bitcoin because if the block limit isn't raised then one of three things will happen: 1. Bitcoin fails. 2. Bitcoin gets used only for moving large amounts of money and other cryptocurrencies take over eventually displacing bitcoin itself. 3. Bitcoin gets used for only moving large amounts of money and "bitcoin clearing houses" fill the gaps, which increase the risk of fraud/theft/unaccountability, add avenues of attack, and form REAL centralization. Not some hypothetical BS.

"already controversy is brewing"  Wonderful zero-evidence hypothetical BS handwaving there.  Yes, controversy is brewing... among those teenagers clueless about bitcoin and economics.

Bitcoin value and press reports indicate new bitcoin users and businesses every day.  The exact opposite of "back away"

I don't mean to spread doom and gloom. I'm sorry....

You said yourself though in a post a long time ago that it's a marketing issue. And who is most susceptible to that? the clueless .

edit: (and in case anyone was wondering what Justusranvier linked is what I was talking about. Just one case.)

[jgarzik]

Not quite zero evidence:

https://bitcointalk.org/index.php?topic=145498.msg1543934#msg1543934

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

[notig]

Not quite zero evidence:

https://bitcointalk.org/index.php?topic=145498.msg1543934#msg1543934

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

+1

[misterbigg]

After some thought, I want to discard my earlier proposal where the block size is adjusted to keep the sum of the subsidy and fees at 50BTC (or some constant). I think that over time, a rise in the value of Bitcoin will hurt demand for transactions, since they will be so expensive.

Here's some more elaboration on what I consider my best proposal, the voting method:

1) A boolean flag is added to each block. The flag represents the block solver's yes or no vote for increasing the block size. The independent miner or mining pool sets this flag according to their preference for an increase.

2) Every time the difficulty is adjusted, the number of yes votes is counted from the last adjustment. If the number of yes votes is greater than 90%, then the block size is increased by 1%. Both percentages are baked-in constants, requiring a hard fork to change.

It occurs to me that a miner could easily code up a function to output the necessary yes or no vote, based on observable network parameters. Here's an outline:

1) Beforehand, the miner assigns a manual constant FIXED_COST which is the estimated additional expense priced in BTC of carrying blocks that are 1% larger.

2) Every time transactions are chosen for a block, the mining software puts together two candidate lists of transactions. One is the normal list which fills up to the current MAX_BLOCK_SIZE. Presumably, it is optimized to include the transactions paying the highest fees per kilobyte. The second list is put together in a similar fashion, but it filled up to MAX_BLOCK_SIZE plus the 1%. It is the first block which is hashed and mined.

3) To determine whether to vote yes or no, the mining software compares the sum of fees between the regular block and the larger block. If the fee increase afforded by the larger block is greater than the FIXED_COST, the mining software stores a yes vote into the block to be mined.


Using this technique, information about the transactions in the memory pool can leak into the blockchain in a way that doesn't require trust and cannot be gamed. The transaction memory pool will influence the decision of increasing block size, but only in a way that preserves the fees.

Since the block size never goes down, we are not vulnerable to the problem where Bitcoin appreciates so much that fees become prohibitive - users will simply send transactions with smaller fees. We also avoid the problem of killing demand for transactions from fees that are too high. Once the fees in filled blocks reaches the equilibrium point, miners benefit from including additional transactions with equal fees and therefore will vote yes (as long as it covers their FIXED_COST).

I believe this is the best proposal on the table. Have at it

[hazek]

Not quite zero evidence:

https://bitcointalk.org/index.php?topic=145498.msg1543934#msg1543934

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

Not only can they be but they already are!: Mtgox allows user to user transfer, so does BitStamp and most if not all other exchanges, then we have Coinbase, a platform who's main goal is to be the Paypal of Bitcoin, any eWallet service that has a shared wallet could offer this feature, any business that takes deposits and has a shared wallet like SealOfClubs could also offer this feature for their users, ect, ect, ect

[MoonShadow]

Not quite zero evidence:

https://bitcointalk.org/index.php?topic=145498.msg1543934#msg1543934

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

Not only can they be but they already are!: Mtgox allows user to user transfer, so does BitStamp and most if not all other exchanges, then we have Coinbase, a platform who's main goal is to be the Paypal of Bitcoin, any eWallet service that has a shared wallet could offer this feature, any business that takes deposits and has a shared wallet like SealOfClubs could also offer this feature for their users, ect, ect, ect

Silk Road can do this as well.  Track that, bitches!

[justusranvier]

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

What changed in your understanding of marketing during the last three years?

https://bitcointalk.org/index.php?topic=1347.msg15145#msg15145

It's hard enough to sell the idea of a distributed cryptocurrency without also needing to explain that we need more than one of them to get full functionality. That will tend to make merchants who would otherwise adopt it just throw up their hands and forget about the whole thing.

[gmaxwell]

It's hard enough to sell the idea of a distributed cryptocurrency without also needing to explain that we need more than one of them to get full functionality.

Who says you need more than one currency?

The cluelessness in this thread astounds me. How do people manage to keep repeating the same factually incorrect claims after they've refuted in allcaps?

[misterbigg]

Who says you need more than one currency?

The current network is just the base settlement layer...organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

The cluelessness in this thread astounds me. How do people manage to keep repeating the same factually incorrect claims after they've refuted in allcaps?

Some folks cling to dogma and don't actually read all the responses.

[justusranvier]

It's hard enough to sell the idea of a distributed cryptocurrency without also needing to explain that we need more than one of them to get full functionality.

Who says you need more than one currency?

The cluelessness in this thread astounds me. How do people manage to keep repeating the same factually incorrect claims after they've refuted in allcaps?

Call the "other layers" whatever you want, but if it turn out the scalability restrictions on the blockchain are not lifted people are going to look at the wiki, and look at the threads talking about this and conclude they've been taken in by a bait-and-switch. Bitcoin is not being advertised right now as a base settlement layer that the average person will never be allowed to interact with directly but instead will be required to interact with a third-party entity who is privileged enough to use one of the 200 million permitted transactions per year. Bitcoin will not be served well by the appearance (justified or not) that vested interests want to keep the transaction rate crippled in order to promote their pet projects and alternative cryptocurrencies.

The worst thing that can happen for Bitcoin is for scalability solutions to exist, but not be adopted for political reasons.

[notig]

Some folks cling to dogma and don't actually read all the responses.

You misquoted that last one.....

And I think there is misunderstanding because everyone isn't on the same page including the developers. For instance

I think there are some things we can all agree on.

We're all keen to see efficient protocols built on top of Bitcoin for things like micropayment channels (which allow lots of fast repetitive satoshi-sized payments without impacting the block chain), or trusted computing (which allows offline transactions to be carried around in long chains until final resolution). Also the payment protocol should eliminate the most absurd abuses of micropayments like SDs messaging system. These things fall into the class of "no brainers" and were discussed for a long time already.

Other more exotic ideas like Ripple-style networks of payment routers using contracts don't seem against the spirit of Bitcoin if they keep the low trust aspects of the system.

At the same time, as evidenced by the disagreement on this thread, there are too many unknown variables for us to figure out what will happen ahead of time. The only way to really find out is to try it and see what happens. If Bitcoin does fail to scale then the end result will be a smaller number of full nodes but lots of people using the system - this is still better than Bitcoin being deliberately crippled so it never gets popular because even if the number of full nodes collapses down to less than 1000, unknown future advances in technology might make it cheap enough for everyone to run a full node again. In the absence of a hard-coded limit the number of full nodes can flex up and down as supply and demand change. But with a hard-coded limit Bitcoin will fail to achieve popularity amongst ordinary people and will eventually be forgotten.

now there is this

Sigh, they need to do more research.

Transaction rates can easily scale far beyond 7 tps, even with 1MB limit in place.

The current network is just the base settlement layer.

Many organizations will layer instant payment networks, settlement networks, credit layers and other things on top of the current layer.

Anybody who looks at the current technology and assumes "that's all there is" or "the whole world is limited to the current network" makes fatally flawed assumptions.

Satoshi openly acknowledged this by noting insuitability of microtransactions for the current network, and it is clear that digitally signed messages may be sent, exchanged, combined by a myriad different payment processors, aggregators etc.

Those two quotes overlap but they don't quite coincide if you notice.  In mikes it would appear "deliberately cripple" means not raise the limit from 1 MB ever. garizk's on the other hand said it can scale even with the limit.......... correct me if I'm wrong plz

[jgarzik]

What changed in your understanding of marketing during the last three years?

https://bitcointalk.org/index.php?topic=1347.msg15145#msg15145

I'm glad you asked

Being the person who actually posted a faux-patch increasing the block size limit, it is important to understand why I disagree with that now...  it was erroneously assuming that the block size was the whole-picture, and not a simple, lower layer solution in a bigger picture.

The block size is an intentionally limited economic resource, just like the 21,000,000-bitcoin limit.

Changing that vastly degrades the economics surrounding bitcoin, creating many negative incentives.

[justusranvier]

The block size is an intentionally limited economic resource, just like the 21,000,000-bitcoin limit.

I can not reconcile this statement with the comments made by Satoshi in the rest of the thread. Apparently nobody knew it was "intentionally limited" back then, including the designer.

I'll accept that you and other developers changed your mind at some point about whether or not to increase the block size, but that leaving it limited was the plan from the beginning is not at all credible.