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801  Other / Meta / Re: Where are you 'Iamnotback'? on: May 04, 2017, 08:33:46 AM
a huge number of sock puppets.  this guy literally loves to talk to himself.

Why are you on a forum where there are essentially, to your view, only two participants: "you and your sock puppets" and "us" ?

That said, it comes close to my view on the world: "me", and "the others" Smiley
802  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 04, 2017, 07:45:37 AM
could you explain in a few words how increases in money velocity affect prices, i.e. raise price inflation (not to be confused with monetary inflation) at a microlevel.

I did already.  Of course, increasing velocity increases inflation.   But monetary velocity is something that is hard to influence with technical means, it has a life of its own.  Greater adoption doesn't necessarily mean proportionally greater velocity, which would be needed to oppose the deflationary effect of "sound money" (no or very small debasement).  In fact, the more economic circles would get closed, the less conversion to and from fiat would be necessary, and the lower the velocity would be (if bitcoin were a currency, not used for speculation and hodling).

Your theory needs velocity to increase proportionally with adoption to keep a more or less constant price.  This has never been seen.
803  Alternate cryptocurrencies / Altcoin Discussion / Re: BTC is DYING, LONG LIVE THE NEW KING LTC on: May 04, 2017, 07:28:26 AM
~ Jan 30th, 2017
BTC Price was $922.95
LTC Price was     $3.86

Now on May 04, 2017
BTC Price is $1500.13
LTC Price is     $21.78

BTC Price increased by ~62%
LTC Price increased by
~564.3%

Writing is on the Wall People , Profit from it or ignore it , your Choice!

$1000 invested in BTC would now be $ 1620

$1000 invested in LTC would now be $ 5643   Cheesy Cheesy Cheesy


Class Dismissed.  Smiley

 Cool

Well, crypto being essentially a set of speculative tokens, very "complex derivatives" like, I think the diversification of the market cap in crypto is what we are witnessing, because the sky is higher in alt coins, than in bitcoin.

Essentially, instead of having one "serious" crypto (bitcoin) and a lot of "cheap immitation shitcoins" like altcoins have been treated for most of the time, we now have a portfolio of different speculative assets on which one can gamble.  The more "established" they are, most probably the lower short-term risk, but also the less you can expect from them to grow.  You cannot hope for a bitcoin growth of a factor of 5 in the short run ; while this is what certain alt coins did, recently, and not the $10 000 market cap coins, but BIG alt coins, like LTC, DASH and so on.  As such, there's much more speculative money to be made on these coins, than on bitcoin.

This is a self-enforcing cycle: in as much as bitcoin is still very big, and hence considered "safer", these other coins are growing in cap until they will reach a certain kind of maturity, like bitcoin.    This will further erode away bitcoin's special first mover/biggest network, of which the difference with coins like LTC will fade away over time.  We'll get an ever-growing list of big coins, and an ever-growing, and unpredictable list of "fast-money-makers", until this system becomes totally random, big coins start to tumble down, at which moment, a perfectly efficient speculation market is established, where no rises and falls can be predicted.

In all of this, the actual "technical merit" of the coins are just a hype-tool, and have nothing to do with reality.  Crypto is like the derivative market on steroids.

804  Other / Meta / Re: Where are you 'Iamnotback'? on: May 04, 2017, 05:51:04 AM
I have already stated upthread that my hope would be to only engage you on a decentralized forum wherein I could "edit your posts" for brevity and "delete" your insolent posts when they are accusing me of being deluded

Visibly your "insolence meter" is asymmetrically calibrated.  This is probably one of the reasons why you end up banned from online social interaction here, which, from an intellectual point of view, can be regrettable, but which, on the side of politeness, is understandable.

Quote
As I explained, these moderation actions would only appear for those who had chosen to have their forum client software follow me as a moderator. All your posts would remain fully intact on the blockchain, and any reader could view them if they want to. So in no way would I propose a system wherein I could censor you, yet if I am a popular moderator, I can influence you to structure your discussion to be more concise and to avoid adversarial ad hominem allegations that can't be falsified.

Such a rudimentary system existed in the 1990-ies as I said before: it was called usenet, and had a simple, decentralized protocol: NNTP.  Nobody ever bothered writing a filter script on top of it, but that is something that could be done with not too much hassle.  usenet died because it crumbled under gigabytes of daily spam ; but what is spam for one, is interesting for another one.  I used to hang around in the sci.physics section, where every lunatic was exposing his rants about his theories of the universe, making normal talk about normal physics essentially impossible.  That's how sci.physics.research was born, with moderation.  Now, of course, to most of us, those lunatic "original thinkers" were spammers writing every thread full of bullshit, but for a limited audience, they were of course visionaries that exposed the conspiracy and idiocy of academia.  So who's to decide ?  Of course you could add blacklists.  Yes, you could even distribute black lists.  But it was a pain.

On the other hand, if you want to vent your own opinions, the internet allows you to have your personal blog where you are master.  Nobody stops you from citing other blogs, picking out what you like, and comment it.  If you are a popular blogger, people will read your stuff.

However, attracting attention to your blog is much more work that profiting from the attraction of an existing centralized forum.  I guess that's why you are here - that's why I am here: both of us want the easiness of picking in on the existing success and social gathering of this forum, instead of going through the difficulty of trying to build such a community from scratch, with all chances of it failing.  I want to have people answering my stuff, so that I can learn from it, and I have my own method of provoking answers, which is not necessarily adversarial to the system I'm (ab)using.  The price to pay to profit from some other entities' popularity, is to accept their power and rules. BTW, this is why many decentralized systems are doomed: people, in general, are willing to pay a price of power, to get easiness back from it.   Usenet was a precursor of decentralized discussion.  People prefer, by large, centralized versions of it.   If you want to have decentralized discussion, restart usenet, and add a "Joe's moderation preferences" script to it, with a moderated group mod.prefs.joe, which contains the encodings of his daily moderation preferences ; or Joe can also put his moderation preferences on his web site.  Nothing difficult.  Nobody will use it.  Hell, there were moderated groups on usenet too, the only ones that were actually usable.  Everybody could start his own moderated group.  Most people didn't.

I've been moderating scientific discussions for a long time, until I really got enough of it.  I respect the moderators on a big forum like this: it is an ungrateful job, and it is difficult to keep one's cool sometimes.  Of course, sometimes, when things don't happen the way you think is fair, a suspicion of conspiracy against your ideas is easy, because the power structure is opaque.  As I've seen the other side for years, and if you see the free investment by people, you know that this is most likely not the case.

This is, BTW, something that crypto is entirely killing: free engagement.  Everything that was freely given away, is now subject to accountancy.  Your idle computing time that could be used for voluntary projects, is taken away because you can use it to mine some coins ; discussing on a blog becomes an act to be paid for in coins ; when free generosity becomes a matter of accountancy, there's no fun to be had any more.  Crypto is killing the last bit of freedom by trying to make everything to be paid for.

You are popular.  You can have a popular blog.  You can of course copy whatever you want from this forum to comment on your blog.  That's exactly what you are proposing.  What's the problem ?
805  Bitcoin / Bitcoin Discussion / Re: Satoshi Nakamoto's stack on: May 04, 2017, 04:36:17 AM
And satoshi don't like to crash bitcoin economy due to his greed.

There are many different logical possibilities, but the most obvious ones are these, to me:

A) Satoshi is a person
- he's dead and his heirs didn't know who he was
- he believes in bitcoin taking over the world's economy ; then it would be silly to sell his coins for a billion, when he can get a trillion and be "master of the world"
- he would have liked to sell them, but he doesn't know how to do so without giving up his anonymity: for sure, the exchange on which he sells the coins will know who he is, or to what bank account he withdraws.  He was already pretty paranoid in the old days.
- he didn't bother to keep the private keys ( <-- cannot believe this)
- he never had the keys himself, because he was working for someone.

B) this last point brings us to: Satoshi is an organisation.  In fact, the points are similar
- the association doesn't exist any more (for instance, the keys were in escrow, and the different signees don't agree to get together any more/are dead/are in prison /....)
- they are waiting for bitcoin to take over the world economy at which point they own a big part of it and will be the rulers of the world
- they don't know how to cash out without getting caught/found out
- on purpose, they didn't keep the keys, because they wanted to establish a system that would modify the economy/finance
- they were a group, doing this in command of a higher entity (a state, a rich family, a terrorist organisation, ...)


I would rule out B) in it's entirety. It's simply impossible that an organization remains coordinated enough that after 8 years there isn't a single leak of who or what satoshi was, and none of the members of the organization have moved a single coin.

My take is that A) satoshi was a single entity, and this entity either died or somehow lost his coins. Even if he believed in his creating 100% and knew BTC was going to be worth $1,000,000 each in 10 years, he would be too tempted to cash out some of them just in case. So unless he was already a multimillionaire and didn't care, it doesn't make much sense.

So either dead, or lost keys for me.

I wasn't giving my personal opinion, but rather all the logically not totally implausible possibilities, from which we can then try to eliminate branches that are too much in disagreement with what is factually known.  I'm not entirely excluding "organization" however, because this may indeed be an explanation why the coins never moved: no single entity HAS the keys.  I agree with you that it cannot be a LARGE entity.  But 5 people or so, why not ?  5 people that are sworn together to become the rulers of the world and have the means to kill one another if ever someone fails ?   After all, how big is something like the Equation group ?  (I'm not suggesting they are the same, but of similar constitution).

That said, there is indeed no need for this to be a group: the work and the quality of the work are perfectly "deliverable" by a single relatively smart and competent person after all.

I'm also not entirely convinced of the idea that they will never move.  After all, you don't do all that work if you think it is shit, and will go nowhere.  You don't break your head to have cryptographic protection for centuries, if you think it will be forgotten 10 years from now.  As this stuff is perfectly designed to be a speculative asset with a price that "goes moon", and you think that this thing will take 20-30 years to go mainstream, why on earth would you expose yourself to being tracked earlier, if you can be the master of the world 10-20 years later ?  If you bet a coin will be of the order of a few million $ of today's worth, why on earth would you cash out on a measly exchange when it is thousand times below its value, and you expose your identity when it is not yet powerful enough to keep it safe at that moment.

I do not exclude that bitcoin is one of the biggest financial hold-ups in history, or at least, an attempt to it.  In fact, the potential to financial hold up is larger than anything that has ever been achieved by armies and politics: no single person has ever held 5% or more of the total financial system.  If the delusional dream of bitcoin comes true, namely, replacing the financial system, we have an entity that has more than 5% of the total system in hands and is entirely unknown.  Personally, I don't believe in it overtaking the financial system, but that was clearly not the PoV of the creator of the system.  So it looks to me like a perfectly logical explanation of why none of these coins have moved: they are waiting to rule the world.

It is this last potential aspect that makes me think rather of a group.  Why would an individual be interested in "ruling the world 20-30 years from now" ?  You can be dead.  You will be old (unless you are very young when you made it).  What's the point ?  However, an organisation with some "destiny", that's something else.  This is why I don't exclude the possibility of it being a group, even though the communications by Satoshi really sound like if he was just a dude in his basement.
806  Other / Meta / Re: Where are you 'Iamnotback'? on: May 03, 2017, 03:02:54 PM

^
I'm more convinced than ever that you are.  Cheesy

If I am without knowing that myself, I REALLY need a psychiatrist !  Cheesy

Hell, how am I going to find out ?  Shocked
807  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 03, 2017, 02:43:16 PM
I think the "crypto as currency" part will shine once physical cash is removed, never before. Theres millions of people out there surviving by working under the radar. The typical guy doing small scale construction work like remodeling or fixing kitchens, or plumber type of jobs, tons of freelancers doing website stuff, coding etc.. I don't know, there's an endless stream of cash being used to work to avoid taxes because it's the only way those people can pay the bills.

This is also my view on crypto, as an underground economy money, like cigarettes in prison, to avoid state, law and taxes.  However, for these people, it shouldn't be a speculative tool, it shouldn't be used by big finance and it shouldn't be large enough to get on the radar.

Because that's the big OTHER problem of bitcoin: because it is mainly a speculative tool, speculators now want *regulation* so that their speculative asset is protected from 'a bad name', to get as many Joe Average as greater fool adopters making them rich, as possible.  Who says, regulation, means also, limitations of its use without asking questions, transparency with respect to (fiscal) authorities etc...
Japan's regulatory frame gives an idea of what is bitcoin to become: a very closely looked-at asset on which you can speculate legally as much as you want, from the moment that you can explain everything and pay taxes on your gains.

Quote
Once cash is removed, those people will be *forced* to learn about bitcoin and use it to get paid in exchange of their services. Then word of mouth will spread and everyone will be using it as a substitute for cash that never enters the banking system.

I'd rather have them learn about monero or zcash, honestly.  Bitcoin is too traceable, has too high visibility now.  But even these coins are too speculative.  Zcash did an effort to have a sensible emission curve in the beginning.  Monero, at least, has tail emission.

808  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 03, 2017, 12:55:12 PM
If you have 25% of the hash rate, and you decided to make 900kB blocks, you only waste 10% of the lower paying fees, and slightly reduce your chances of orphanage. Spamming the system then won't get your fees back without collusion. Why don't the miners just collude to going back to 500kB blocks now, pushing fee rates even higher?

To do that, there's need for collusion and OPENLY SHOWN collusion, that is clearly "against" the interest of bitcoin users.  There is no *individual* financial incentive for a non-colluding miner to start mining 500 K blocs.  If you do it on your own, you can only *moderately* pressure the fee market, so the fees won't increase much, and you waste systematically 50% of the fee income.  If all miners do it, here is your proof of total centralization and collusion !  Moreover, if all miners mine 500K blocs, you still only compressed the fee market by 50%.  It would seem totally impossible for miners to mine 100K blocs and still have some ounce of credibility.  Outrage would prevail.

If you want to compress the fee market, not a little bit, but significantly, by eating up, say, 90% of the room, apart from having all miners collude and only mine 100 K blocs, you can decide that totally for yourself, by spamming the pool entirely, so that 90% of what goes on the blocs is your spam.  That will cost you fees to your competitors, but everybody can continue mining 1 MB blocs and all miners can pretend not to be involved.  

By pressurising the fee market, you have to pay the fees, true, but you will create a lot of high-fee transactions by desperation on the mem pool, transactions with fees that wouldn't, by far, be there if there was no desperation.  When the mem pool is full enough, you can start mining *those* transactions (which cannot be widthdrawn !), with much higher fees than you would have gotten if you didn't do the spamming.  So you get finally back most of what you spent on spamming, and you've gotten the market used to higher fees.  Rince and repeat.  Maybe the following spam campaign will be done by a competitor.

The idea is not so much to have gains directly from spamming, the gains are in the longer term when people get used to paying higher fees systematically.  With spamming, you can reduce the effectively available space to essentially nothing ; with making smaller blocs you can only pressurize the fee market slightly (not more than your hash rate percentage).  The outrage if you make small blocs will be much bigger than if the network is spammed, too.

809  Bitcoin / Bitcoin Discussion / Re: Is diversity in bitcoin client implementations a good or a bad thing? on: May 03, 2017, 12:17:13 PM
So is there some kind of succession bloodline to who is the rightful heir and dictator of the bitcoin reference implementation since Satoshi left? Is it the last claimant left when all others have been put to the sword or banished from the land of bitcoin?

I thought that Satoshi gave the github keys to Gavin ?
810  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 03, 2017, 12:15:10 PM
They don't need to spam the network to create fee pressure. They can just create smaller blocks when the transaction demand is low.

The difference is of course, that creating smaller blocks is a visible and individually lossy strategy, while spamming is a much more versatile, flexible, anonymous and (between miners) consensual way of regulating the fee market pressure.

I think you need to explain this logic to me. I doubt it would hold up to closer scrutiny. I doubt they care if smaller blocks are visible. Why is it individually lossy?

If you make, as a miner, smaller blocks, you have less fees than your competitor but your effect on the fee market is limited, so there's no individual reason to make small blocks, and other miners win more and relieve the fee market pressure at your expense.  If you spam the pool, you increase the fee market pressure uniformly, and you get back your hash rate fraction of the fees you spend ; moreover, nobody knows that you are the "nasty miner": you mine what you can, with full blocks.

If you have 25% of the hash rate, and you decide to make 200K blocks, you can only diminish the available room on the block by some 20%, and you waste 80% of the fees you could obtain.  If you spam the pool, you can pressure the fee market as much as you like, and it costs you about 3 times the fees you obtain (you spend 4 times the fees if you fill all the blocks, but you get back 25% of it) ; if you are the only spammer.

So essentially, instead of diminishing the room only by 20%, you can diminish the room by almost 100%, for 4 times the fee price you would have had with low pressure ; but given the high fee pressure, the fees will be higher too, filling up the mem pool.  When the mem pool is full of "large fee desperate transactions", you can mine them and reap them in.  Maybe next time, another colleague miner will do that.

Spamming gives you, as a miner, hence a flexible way to contribute to the fee market pressure, where you can pressurize the market entirely, at a cost that you can mainly get back by the pressurized high fees when the mem pool is full.

Call it "pump and dump" of the fee market if you want.
811  Other / Meta / Re: Where are you 'Iamnotback'? on: May 03, 2017, 12:03:05 PM
dinofelis is the same guy (anonymint) same style, same talking points.

I don't know if I should take that as a compliment, or whether I should hurry seeking a psychiatrist  Grin

Seriously, I'm really not Shelby.  He's much more expert that I am, but he's also much more deluded than I am (and he considers me an idiot, which he would never think of himself).

To Shelby: go and do your thing now, that's much more important.
812  Bitcoin / Bitcoin Discussion / Re: Bitcoin and deflation on: May 03, 2017, 11:36:04 AM
and why it is not a currency, but a speculative asset.
This is why central banks issue more currency

not a currency??
anything can be a currency.

Well, I take a currency to be an intermediate storage of value, that *keeps more or less its value* between an act of obtaining value and an act of spending value.  One of the principal properties of a currency is that it is a more or less reliable unit of account, that is, that its unit has more or less steady value (or a predictable slight increase or decrease in value).  In other words, a thing that doesn't change 30% over a month or so.

Because if it is rising by 30%, you don't spend it (you hoard it).  If it is falling by 30%, you don't accept it (hyperinflation).

813  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 03, 2017, 11:32:20 AM
You certainly underestimate miners' roguishness (or whoever acts through them). While I agree that miners might be discouraged from clearing the mempool but this just proves how rogue they are. And here's the crux of the matter. What prevents them, first, from flooding the network with spammy transactions, and, then, filling the blocks with this trash? And right then we are back to square one, or even worse, since we would have larger blocks then (read it will be more difficult for Bitcoin nodes to support the network)

Well, this is built into bitcoin from the first day.  After all, the diminishing bloc rewards, and the necessary transition to fees paying for mining need a fee market that can be pressurized to the level the market can bear ; that is, the highest possible fees that can be extracted from the system without making it crumble under its own costs.  Bitcoin was simply designed that way, by combining reward halvings, inflationary spiral, and PoW.  Whether that was intentional or not is a question of course, but the reality is that this is an unavoidable consequence of the design.
814  Bitcoin / Bitcoin Discussion / Re: LN+segwit vs big blocks, levels of centralization. on: May 03, 2017, 11:28:34 AM
It is really strange that you ask this question

As I got from your previous post, you yourself say that miners will be deterred from creating super sized blocks because "clearing the mempool on every block will produce zero fee pressure". Miners are vitally interested in producing this "fee pressure". I agree that they risk increasing their orphan rates at that, but since we see that mempools are never left empty these days, it seems that the latter doesn't deter them from pumping more "fee pressure" into the network

They don't need to spam the network to create fee pressure. They can just create smaller blocks when the transaction demand is low.

The difference is of course, that creating smaller blocks is a visible and individually lossy strategy, while spamming is a much more versatile, flexible, anonymous and (between miners) consensual way of regulating the fee market pressure.

815  Bitcoin / Bitcoin Discussion / Re: Bitcoin and deflation on: May 03, 2017, 09:36:14 AM
In order to distinguish both concepts, one can use the terms "inflation and deflation" to the value of bitcoin, and *debasement* to the "printing of bitcoin".

A currency is deflationary (rises in price) whenever its debasement is less than its adoption.

A currency that is strongly deflationary, falls most probably in a deflationary spiral, where hoarding and speculation overtakes its use as a currency ; in other words, it becomes a speculative asset.  That's exactly what happens to bitcoin, and why it is not a currency, but a speculative asset.

This is why central banks issue more currency when the economy is growing: to keep its value from rising (in fact, most of the time, they want its value to decrease slowly, so that people don't hoard currency).

*slight* and *controlled* deflation and inflation don't matter, because one can use them in any price projection of the future.  However, wild deflation leads to the currency to become a speculative asset, and wild inflation leads to hyperinflation, and total loss of monetary belief.
816  Bitcoin / Development & Technical Discussion / Re: The case for moving from a 160 bit to a 256 bit Bitcoin address on: May 03, 2017, 09:31:32 AM
- snip -
And yes, thats the risk-- that your counterparties degree of freedom in choosing part of the contract will let them find an alternative contract with only collision like work, rather than with second-preimage like work.

You can mitigate by having multiple rounds of communication with commitments, but few to no one will implement this in practice:  Each communication round is a huge software engineering and UI cost, and most people don't understand this collision vulnerability (or _any_ collision vulnerability) even after having it explained.
- snip -

So, the solution to this (for me) is to insist that I'm the one that generates the contract address.  This removes the counterparty's ability to engage in this attack.

If the counterparty is aware of the risk and doesn't have reason to trust me, then their only recourse is to offer the "multiple rounds of communication with commitments".

Since in practice "no one will implement this" AND "most people don't understand this collision vulnerability", the odds are that I can almost always get away with being the one to generate the contract address every time (unless I'm engaged in a transaction with gmaxwell, since he understands enough to know better).  Someone may eventually fall victim to this, but I now understand enough to keep myself safe (from this particular attack).

... and invest in it to attack others Smiley
817  Alternate cryptocurrencies / Altcoin Discussion / Re: Idea: Scalable, flexible altcoin on: May 03, 2017, 09:29:15 AM
What we have at the moment are multiple blockchains for multiple cryptocurrencies, which all have their own communities. And while some of them might be in the hands of few people, while others might be spread out more, the blockchain ecosystem as a whole is heavily decentralized. We can expect users to wander off to other blockchains/currencies, should a blockchain fail.

THIS !

The only thing that is missing in this puzzle, are decentralized exchanges that link together different (not all) block chains and are really used.  If one has to go through a centralized exchange, all of this "decentralization talk" is moot.

And I like a lot the idea of an ecosystem of block chains, where coins get born, live their life, end up corrupt, centralized, old-fashioned and bulky, and die slowly away.  That would eventually solve the "early adopter seigniorage" which we can see can lead to dangerous and immense fortunes if ever certain coins (of course bitcoin, but some others) keep on living and growing.  If coins get born and die, this would finally take out the speculative domination of this eco system, which kills it.  There's no more reason to "hodl for eternity".  
818  Bitcoin / Bitcoin Discussion / Re: Is diversity in bitcoin client implementations a good or a bad thing? on: May 03, 2017, 08:43:24 AM
I think it is necessary, in order to separate the protocol and the software, because otherwise, the software defines the protocol, and the authors of the software are then also the masters of the protocol, giving "hidden power" to the software writers of the "official client".

Of course, that depends on how one sees the protocol.  One can admit that the protocol is whatever the software writers decide it is, and can change it to their desires.  If that is explicitly stated, then of course, there can only be one implementation, and one has explicitly taken the view that the protocol is whatever the software does: a kind of "smart contract" thing, but which is not immutable, but modifiable by one team.

However, in as much as one thinks of a crypto currency as a protocol graved in stone that is essentially never to change, and implements true immutability, then the only way to have this immutability of the protocol is by having a lot of competing implementations, that can never settle on any agreement of change by their mutual antagonism, in the same way that miners cannot settle on a modification of the block chain history, by their mutual antagonism.

I would like to add that "immutability of the block chain" with a mutable protocol, is meaningless, as we saw with ethereum.  If you can change the protocol, you can change the meaning of the past block chain and the rights it grants, so even if the binary data remain the same, the mutable protocol can do anything with it.  Hell, a mutable protocol could even take away Satoshi's stash in principle.  So in as much as immutability means something, the protocol too, has to remain immutable, which can only be established if there is such a big zoo of software implementations, that any agreement on change is impossible (except maybe for obvious bug fixes that affect no economic relationship).

That said, what matters is not the user client, it is the miner software that defines the protocol, because they are the ones that make the chain, and, as gmaxwell said, the currency protocol is whatever the miner pools decide it is in practice by making a chain according to their mutually agreed-upon rules and protocol, unless a user subset agrees upon forking away and changing to PoS or another PoW algorithm (but that only shifts the power to another set of miners).

User clients have to adapt to whatever the miners make as a block chain.  This is a bit like web browsers: user web browsers must adapt to the protocol that web servers use.  Except that here, there's only one "web server": the block chain made by the consortium of miners (about 20 pools, of which 5 have majority).  If your "browser" doesn't understand the protocol of that "web server" it will give you faulty information, or it will indicate that the page is not valid ; it will emit transactions that will not be recognized by the "web server" (the block chain makers).  So the only thing to do, is to use a compatible browser.

But of course there is a feedback: in as much as a web server wants to serve pages that are "looked at", block chain makers want to make a block chain on which users want to buy tokens.  So web servers will make pages that can be looked at by browsers, and block chain makers will make a block chain that will be used by token-buyers.
819  Bitcoin / Development & Technical Discussion / Re: The case for moving from a 160 bit to a 256 bit Bitcoin address on: May 03, 2017, 08:25:44 AM
- snip -
Now, the nasty thing with a double signature, is that the guy providing HIS signature has a lever on the true document, and is hence able to find a collision with a document entirely of his making.  This is what reduces the 160 bit second-pre-image security to 80 bit collision security.

Am I right in assuming that this reduction in security is because the attacker can generate 279 reasonable looking 2-of-2 contracts (and their associated P2SH addresses), and then generate 279 single-signature P2SH addresses, and in doing so would have an extremely high probability of finding an address in the set of 2-of-2 contracts that collides with one of the single-signature P2SH addresses?

279 contracts + 279 single-signature P2SH addresses = 280 generations.

Or more specifically, that the attacker can:
  • 1. Generate one 2-of-2 contract and one single-signature P2SH addresses and see if they collide...
  • 2. Then generate an additional 2-of-2 contract and see if it collides with ANY of the single-signature P2SH addresses generated so far
  • 3. Then generate an additional single-signature P2SH addresse and see if it collides with ANY of the 2-of-2 contracts generated so far
  • 4. Repeat steps 2 and 3 until a collision is found

And that in doing so they will succeed, on average, after repeating steps two and three 280 times (although they could get lucky and collide sooner, or get unlucky and collide much later).

Is that the risk here?

Yes. Up to a few factors of 2, we're talking orders of magnitude here, not an exact amount of trials.
820  Bitcoin / Development & Technical Discussion / Re: The case for moving from a 160 bit to a 256 bit Bitcoin address on: May 03, 2017, 07:50:42 AM

I did, but didn't get it, but maybe I do now on rereading: We're talking about a collision of two P2SH addresses. That makes sense.

Yes, it took me some time to understand that too.  The "lever arms" are a couple of private keys drawn from a set, that gives rise to a couple of public keys, to be combined with conditions (one is the counterparty's public key, the other is an own public key arbitrarily chosen of which one has the private key), giving rise to two P2SH hashes.  One only needs to test on average a set of 2^80 private keys to find such a couple that has identical such P2SH hashes.
Note that it is somewhat more involved than just testing 2^80 private keys ; one needs to store somehow these results to find out what couple has a collision after the fact.  


So once you do that, how does the attack work? How do you get the other party to use the compromised keys in the multisig?

The whole point is: you don't need a multisig to get paid out !  I didn't immediately realize this either, but the whole principle of bitcoin is that in order to have the "spending right" of an UTXO, you have to solve a puzzle of which the "question" hashes to the output address of that UTXO.  In a simple transaction, that puzzle is "make a signature that corresponds to the public key that is this hash".  In a 2-2 contract, however, that puzzle is whatever hashes to the given hash ; one such puzzle is the intended multisig: "make a signature that corresponds to the first public key, and make another signature that corresponds to the second public key".
But if you can find *another* puzzle description that hashes to the same hash, the solution to that other puzzle ALSO satisfies the spending requirement of that UTXO.  That other puzzle has nothing to do with the first guy's public key. 
You see, the explicit requirement is not present in the block chain: only its hash is.  So whatever requirement that hashes to the same hash, can be considered as the "true requirement".

Compare it to the following situation: you buy a house, and instead of registering the whole act of sales, you only register its HASH with the notary.   The notary knows that this house goes with that hash, that's all.  So anyone that can write another act of sale, that hashes to the same hash, can act as the owner of the house, the notary will agree, and will let him sell the house while you don't even know it.

Now, the nasty thing with a double signature, is that the guy providing HIS signature has a lever on the true document, and is hence able to find a collision with a document entirely of his making.  This is what reduces the 160 bit second-pre-image security to 80 bit collision security.

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