Bitcoin Exchanges Under ‘Massive and Concerted Attack’
coindesk.com
coindesk.com
That said, this event is extremely encouraging. Not only is the security and the viability of the currency being tested. But more importantly, the communication and cooperation between the major players in the Bitcoin ecosystem is being tested. And so far, the community is kicking ass.
To me that signals that perhaps Bitcoin really is a viable currency for the long term, and that it may really be a great way to think about money and value exchange.
These poorly coded exchanges were looking for an exact hash match to pop up on the block chain, instead of looking for the deposit/address.
The actual security of the system is not really impacted at all, and the core Bitcoin clients cope fine with this. The exchanges may have put themselves at risk, but that is on them.
That's the thing I don't get. If one is going to allow non-essential changes, shouldn't one _not_ include those data in the hash? Alternatively, should one simply not allow changes, period?
I've not read the Bitcoin paper, just summaries (been too busy, and it's outside my area); perhaps there's a good reason for it.
Spending unconfirmed outputs in the presence of malleable transactions is unsafe. The reference client allows spending unconfirmed change outputs as they used to be considered safe. But if the original transactions is modified then the chain of unconfirmed transactions becomes double spent and the reference client gets confused about balances.
The scammer will be able to sell the same "bitcoin" over and over if they want, or set up a fake "Validate your bitcoin here" site.
The type of people that buy from the back of magazines are probably the type that would hang on to this "investment" for their grandchildren... while the scammer is long gone.
At its core, BitCoin is unbelievably simple: a ledger of account, no different than an Excel file, distributed across millions of computers, kept honest through offering rewards for protecting the ledger's integrity. There's really no such thing as a BitCoin, just a row in that ledger that says "1.23456", and only the holder(s) of the key for that row can send a portion of that number to a different row. Like with any form of money, any value derived from that ledger is purely a product of collective belief.
BitCoin is roughly at the place where Mosaic was in the early 90s. The real story isn't about BTC becoming the new world currency; it's a technological and sociological prototype of a new type of distributed application which has only barely begun to be explored.
http://www.michaelnielsen.org/ddi/how-the-bitcoin-protocol-a...
Systems which use the bitcoin mechanic need a lot of adoption before they become trustworthy.
But ultimately, you are correct: bootstrapping a new blockchain-based service requires assembling a community with enough hashing power to fend off 51% attackers. Time will tell how the experiment will pan out, but even if most projects fail, my gut is that at least a few will succeed in the long run.
"Presumed to be well-guarded by many vested interests". Of course, if you don't know who controls how much of the network, you don't know that its guarded by anything, or what the vested interests with influence over the security of the blockchain are actually interested in.
Right now, bitcoins are treated like digital gold. People hoard them and treat them like investment assets.
And for the same reason the world's major currencies unlinked from gold, bitcoins also exhibits recessionary behavior. (bad news for a currency)
The greatest significant bit for spending is stability/volatility. If BTC accumulated value at a steady 3% per year, many would still spend it (especially if vendors offered a 5% pay-with-BTC discount). The problem is that no one knows if BTC's value a year from now will be 10%, or 1000%.
Crypto-currency will either find a stable equilibrium over the coming years/decades, or it won't.
Deflation is fundamentally less dangerous than inflation, because there is less counterparty risk. Technology is supposed to be the "rising tide that lifts all boats", perhaps not surprisingly, technological goods decrease in price in spite of inflation. But by inflating we rob society of the value created by technology and distribute it to bankers and government contractors. It's really sad, and a large reason why the rich get richer and the poor get poorer.
Seems like every American is going to have trouble with this, since they are not taught how to use decimals and powers of ten. The rest of the world will do just fine using mBTC and uBTC.
This narrative is consistent with 1000s of years of history, e.g. Diocletian cutting his gold dinars with silver [2] (and enforcing its fiat trade value), many many examples in small european fiefdoms prior to the dark ages, and again at the end of the renaissance.
At the end of all of these periods, the survivor was gold, because it kept its value and inflation proved to be unsustainable and extremely destabilizing to the society by propping up incompetent economic and political 'winners'.
[1]https://www.youtube.com/watch?v=JUvm9UgJBtg [2]https://en.wikipedia.org/wiki/Diocletian#Currency_and_inflat...
The U.S. domestic economy unlinked in 1933, permanently. Only international trade continued to use gold-backed currency, and it is that aspect which was finally eliminated in 1973.
Likewise you have mixed up your cause/effect for the Great Depression, which started 4 years before 1933. On the contrary, the very election of FDR in 1932 was due to the economic crisis, and the unlinking of gold reserves was in response to the depression, not the cause of it.
One funny thing is that many people who are otherwise economically intelligent get so confused with gold. Holding currency to a gold standard by some fixed price would be called "price control" in any other context, and we already know price controls to be bad policy. By unlinking currency from gold we can well and truly "let the market efficiently decide".
The biggest irony for me with regard to Bitcoin is that it proves the fiat concept. Bitcoin is literally worth nothing more than what people think it's worth; there's no physical thing of intrinsic worth underlying it after all. But this is of course more or less exactly the claim for fiat currency.
If the iternational market for dollars is still linked, in spite of domestic unlinkage, there is still some level of grounding, because of the possibility of commodity arbitrage (both directly and indirectly). Certainly there was inflation during that era, and the dollar slipped so far that it led to Nixon's actions... But for the most part the standard of living was able to keep up, largely thanks to technological and infrastructural improvements. Moreover, you couldn't soak the bankers/financial sector quite as easily because of the international connection to gold (and international currency arbitrage is more important to bankers and finance than your average domestic schmoe).
> Likewise you have mixed up your cause/effect for the Great Depression
Sorry, I should have said, I believe if we hadn't unlinked it we would have only had a shorter, not-so-great depression (emphasis on great, not on depression). Obviously, I'm aware that the unlinking came after the stock market crash of 29.
> Holding currency to a gold standard by some fixed price would be called "price control" in any other context, and we already know price controls to be bad policy.
No, price controls are setting the price relative to a standard that's backed up by guns (guns = "control", as in, if you don't do what I say I can shoot you, or point a gun at you and take you to jail). Dollars are already backed up by guns, so the notion of 'price controlling' dollars makes no sense. If anything, you want to back dollars by gold to keep the people with guns honest.
The dollar is already an 'amarket' entity by virtue of its backing by the state. A better example of 'letting the market decide' in the context of 'valuing currency' would be letting the interest rate float, without manipulation, which is also something we most certainly don't do.
>The biggest irony for me with regard to Bitcoin is that it proves the fiat concept.
There are goldbugs who insist that Bitcoin is silly because it's not tied to anything with 'intrinsic value'. That's one interpretation of the fiat concept. But I (and many others) interpret fiat to mean 'by a higher power' (by analogy to fiat lux) except in the general case of state currencies, the higher power being the authority of the state.
Indeed a gold-backed dollar is still a fiat currency, albeit a more responsible one.
On the contrary, with a fixed-ratio gold standard currency it is still the state who said that a dollar was by definition equivalent with, say, 1/35th of an ounce of gold (as it was just before the U.S. finally abandoned the standard for good). But the only reason the government would give you $35/troy ounce was because of the men with the guns, and the government could change their minds.
In fact, the U.S. did arbitrarily change their mind several times throughout their history about "what gold was worth". This didn't change the market value of gold of course, but this didn't stop the politicians from abusing fiscal policy for their own interests.
The interesting thing is more that there was a market value of gold which was different from the "official" government price of gold, which should illustrate by itself the issue.
Rather there was never anything special about gold except that people thought it was special. The U.S. started off on a gold and silver standard after all, which led to problems fairly soon after since the difference between gold and silver value that Congress decreed was not always the difference the markets created.
While I'll agree it's possible to have gold-backed fiat currency (like the Civil War-era greenbacks), there's no reason why it's "more responsible". It's still just as susceptible to government intervention and it unnecessarily conflates non-orthogonal concepts for the sake of... what?
Gold was only valuable because people thought it was valuable. If you went to a desert island you could form an economy on water bottles. Prisoners actually did form economies on cigarettes, and when cigarettes were banned the currency shifted to cans of mackerel.
As far as I'm concerned gold-backed dollars make as much sense as dollars backed by sardine cans. At least true fiat currencies (and Bitcoin) finally gave up the middle-man and acknowledge that their currencies are worth what people think they're worth. It may be too spooky, but it's the truth.
The gold standard is just inconvenient, period. It restricts the policy space for governments. This can be a good thing, but in democracies - where the government mostly does act in the interest of the population[0] - I would say that it mostly ends up being a bad thing.
> FDR temporarily unlinked in 1933 and we had the great depression
Yes, both of these things happened. The important thing is the order in which they happened: The great depression happened first. Abandoning the gold standard was a somewhat late and indirect reaction to that. In fact, countries recovered roughly in the order in which they abolished the gold standard (see e.g. [1] for references).
Edit to add: As to the history of coin debasement, I genuinely wonder whether historians have got their causality right. There appears to be a self-reinforcing belief that historically, coin debasement always caused inflation. At a superficial glance, that story seems to fit the data, hence the self-reinforcement. However, there are some episodes in the Roman empire where it seems plausible that causality could have run in the other direction: Inflation came first, and the coins ended up being debased to match the reality of how much (or how little) they were still worth.
I know that gold bugs must deny the mere possibility of such a "reverse causality" on quasi-religious grounds, but a sober look at the data leaves quite a lot of room for this. Some of the inflation values use price data that is almost a century apart, and a 5x increase in price over a century is actually relatively modest inflation on a year-over-year basis, if you take the exponential nature of inflation into account. This level of inflation could easily arise endogenously, say out of modest wage-price pressure effects. Changing the coins to adjust to a new reality after a century is then merely reasonable administration.
This is not to say that the story of "bad emperor flooded the market with coins to fund wars" never happened. It's just to say that perhaps history was sometimes more complicated than what fits into a bug's brain.
[0] Yes, yes, come at me with your cynicism; and indeed modern democracies are imperfect. But compare today to the middle ages without prejudice, and you'll see what I mean.
I always like pre hoc ergo propter hoc arguments.
How does that make you feel about dogecoin's decision to allow 5% inflation per year? It's currently the third largest crypto currency (behind Bitcoin and Litecoin) and I think most highly traded coin. Does the inflation make it more viable in the longterm as a currency people will actually use and not just hoard as an investment?
Bitcoin is not headed in that direction, but that doesn't mean someone else can't solve the liquidity problem. Forced inflation may not be it though.
Then read the paper! :) it's not complicated and it's pretty short.
btw do you understand how the banking system works?
If this was two major banks and they said they had to stop withdrawals for 1-3 days to fix a software bug that's been exposed through a concerted attack, one they already knew about and could have prevented, I don't think you would be saying the same thing ...
Ultimately this might prove a footnote in the Bitcoin story, or it might be the harbinger of more trouble, who knows. But I do think it takes quite a bit of spin to think of this as somehow being encouraging or a net positive. I think if this had maybe stopped at Mt. Gox, an exchange that was universally considered a bad player, you could think of it has good overall (ignoring the fact many people would have still been screwed over). But it seems clear it's gone beyond them.
You can stop right there, as Bitcoin is nowhere near the place where it is equivalent in any way, shape, or form to "two major banks". If it was, your critique would be valid. Since, instead, it's more like a bank startup, these kinds of disruptions are expected and encouraging, because it allows third-parties to see how difficulties are resolved, and how robust Bitcoin is or is becoming.
P.s. I have never owned, mined, or otherwise installed or used any software related to Bitcoins. I have no horse in this race whatsoever.
Basically, the price goes up quickly when new people are attracted to bitcoin and rush to buy. When the price dips however, because so much is bought for long term speculation, the price doesn't really dip much, as no one is incentivised to sell and hold out for when it gets better.
At some point the nerve of those holding out may crack, but if you read silly saurus2's post, its quite clear that many will hold out indefinitely on the belief or hope it will one day recover. So in this manner the bubble can deflate slowly. (If you call 10% in a day slow).
There are no settlement dates or ways to easily move money out (especially now) so a crash is prevented.
If a crash happens it'll probably happen before people realise it, but suddenly there just won't be anyone wanting to buy coins anymore.
But even that might not happen as people already invested into bitcoin use how wealthy they feel to buy bitcoins from each other. That can cycle for a long time before people realise there isn't new money in bitcoin.
If you had bought coins at 800-1000, why would you sell now? No one likes to cement a loss.
Those with the most reason to sell right now are the early adopters, but it's not actually clear how many of those coins are actually reachable.
But then if people panic and see how hard it is to get back into fiat from BTC won't they just go into relatively stable altcoins instead? For example DOGE is skyrocketing as we speak and it's USD price was totally unaffected by BTC's recent plummet. http://coinmarketcap.com/
EDIT: "If" -> "Is".
What, you thought other coins had their own code? Nope, they are all just a copy/paste of Bitcoin's code.
Specifically Dogecoin was "coded" (copy/pasted) in a Friday night, according to it's founder. So I don't know what you were expecting.
It will be interesting to see how each developer set and community handle this problem (and the future problems).
Disclaimer: I don’t own BTC or DOGE (or LTC or any other virtual currency).
Typically a copycoin will only have the same fixes as Bitcoin depending on when they decided to copy it. But then they will invariably lag behind.
"The OpenUDC softwares are designed to manage a free money system as described by the TRM (Théorie Relative de la Monnaie), that means a money system where no human has privileges in front of money creation either in time or in space."
The concept is therefore quite different from BTC which clearly gives some people a huge privilege in front of money creation in time
Conversely, unlike stocks, you don't need a broker, so there's nobody who would take on that dealer role.
Nobody has setup a "buy bitcoin on margin" service yet, and the first person to do so will lose a fortune to nonpayment of margin calls.
There also are brokers providing indirect Bitcoin shorting with 1:10 leverage in the form of CFD's (contracts for difference). Of course they could opt to always or sometimes not actually trade the coins - to their clients it makes no difference, as no actual coins can be moved in/out of the accounts.
Some possible ways that it might be interpreted to be more flexible are scripting, n-of-m transactions, and so on.
Reversibility shows up when you do transactions in a bank or other third party that can reverse the transaction on its own accord. There's no theoretical reason why this can't happen with bitcoin instead - you give your BTC to a hypothetical, highly regulated bank or broker or whatever, and then the transaction is exactly as reversible as any electronic transaction using dollars. The confusion sets in when you compare Bitcoin transactions with electronic transactions using fiat currency, when they're closer in many ways to physical cash transactions in nature.
I very much agree with you. This is also the right way to think about BTC exchanges -- an unregulated website that you ship cash to.
There are some subtleties around the specific nonphysical transaction mechanism of BTC that differentiate it from a cash transaction, which are sort of difficult to quantify currently because the technical and legal aspects have not been fully explored... as a hard example, imagine a BTC wallet coupled with a memorizable private key (or an effective substitute). This is essentially a cash store that cannot be confiscated, and which can be communicated verbally, i.e. within a protected (attorney-client) setting. There are some interesting implications there.
Great way of taking the risk created with the volatility of Bitcoin and multiplying up the risk massively so you can lose money even faster...
Was hoping to have a large amount in bitcoin so i can buy online services relatively anonymously.
Since then I more then recovered my loss even at the price it has now.
Maybe Bitcoin would be different if you could put money in but not take it out. But it's actually the reverse now -- it's harder to get Bitcoin out. So wouldn't that tend to increase the selling pressure?
And if you don't want to sell to a sketchy exchange, you can sell to SecondMarket[0] and get a wire transfer to your bank account the same day.
https://www.secondmarket.com/education/sell-bitcoin-secondma...
Not sure how true this is. Bitcoin has been going through a few major crashes in the past 3 years, yet the demand was still strong after it went down.
However this is incredibly unlikely, bitcoin went though a fork last year that caused some problems but was quickly rectified, this current maleability issue is also being worked on to get a resolution. These sort of network wide problems are problems with the fundamentals of bitcoin and should, by right, affect the price of bitcoin much more than say government regulations in China or India, that they dont is because most holders of bitcoin understand that these problems can be resolved with some dev time and BTC has some great and comitted devs working on it.
Namecoin (NMC) had a similar issue where it meant that web addresses linked to NMC were not secure, that caused a crahs but no where near going to zero and that is a coin with minimal developer support.
if you have 100 btc in an offline wallet, you will still have it tomorrow, despite whatever bugs/attacks hit the exchanges.
imagine if your bank was hacked, many people would literally be removed of their money.
With cryptocoins, you have the advantages of keeping dollars under your mattress while still bring able to spend them anywhere that accepts them.
I guess it would be possible.
The double spend attack works by convincing the other party that the transaction has completed (so they release whatever escrow is in place) and then replacing the blockchain.
(But a botnet infection could watch for wallets on a computer and cause the coins in the wallet to be spent)
When you have 51% of mining power, you can do a lot of nasty things(like stopping confirming transaction at all), but not spend someone else's bitcoins.
ASIC owners are paranoid about their earnings. They would notice they are getting less than they usually do the next day after the infection.
http://en.wikipedia.org/wiki/Digital_signature
The purpose of the blockchain is to establish an ordered sequence of transactions.
This is a DDOS attack on the integrity on the distributed database, which is very bad, but not able to spend Bitcoin that isn't yours.
There is no problem with value changing tomorrow as this is a potential problem with any new payment methodologies. Adoption does not appear magically overnight. The US Dollar is velocity stable due to its wide spread use and being propped up by the equivalent of a bunch of duct tape and bailing wire.
The chances of everyone doing this and being comfortable with it is pretty low though. We need brain storage medium.
Not that I think this is the ne plus ultra of security, but since having a digital wallet doesn't obviate the existence of valuable physical documents (eg passports, title deeds) you might still want to use a safe to protect against fire, burglary, and so on.
One distinct benefit of a physical store is that removal or tampering are more obvious.
There was a guy on reddit who had all of his DOGE and BTC lifted right off his computer. He was using strong, auto-generated passwords stored in a password manager, so he was not even typing in passwords that a keylogger could intercept. Presumably the attacker had a backdoor into his system, watched him work, and just transferred out the funds when he wasn't at his desk. Poof - all gone, with more or less proper security measures in place and no clear sign of an intruder other than the missing money. Several other people reported similar events in that thread.
These are still major problems for mass adoption of crypto, completely setting aside the massive cases of fraudulent pools, online wallets, exchanges, etc., etc. There are many subtle problems that are difficult to diagnose and cure that come with a technological solution like bitcoin, that paper money simply does not have.
When he died, my grand-aunt, who always thought he was being silly, went out in the woods and retrieved all the jars.
The cash had rotted and deteriorated to the point that it was unspendable.
However, she was able to work with the US Treasury to sort through the remains and identify the bills and replace them with new currency.
There's not really a bitcoin lesson here, just some family lore that seemed relevant. :-)
These days spending old banknotes is problematic, even if they're in perfect condition.
Some people love gold, some people hate it, but everyone agrees it's the only thing that really has zero counterparty risk.
In both cases, there is one physical good which, when stolen, deprives you off the money. With cash, it's the physical notes. With Bitcoin, it's the private keys in the wallet (or private key to unlock the wallet's private keys). Making backups of the keys can protect against accidental data loss, but not against theft, as it increases attack surface (i.e. number of locations where the same money can be stolen from).
There is still an advantage here favoring Bitcoin, though: if the key is stolen and you know this, you still have a chance to preserve the wallet's holdings: just generate new keys (addresses) and broadcast a transaction of all the wallet's money to those addresses. If you can get the message to the network's nodes faster than the attacker, the money will be "signed away" before they can use it, and such attempts will be rejected as double-spends.
There is no corresponding feature for physical cash.
While you could construct a procedure to spend cash remotely without one powerful intermediate, this property is just built into to *coins, and it is simply how they work.
Are you sure about that? For the most part those transactions would simply be reversed. Bitcoin exchanges seem a lot more exposed to computer security breaches to me.
> With cryptocoins, you have the advantages of keeping dollars under your mattress while still bring able to spend them anywhere that accepts them.
Paper currency is a bearer instrument. It can be used for offline payments. Cryptocoin can't be. Both parties need to be connected to the rest of the coin network so the transfer can confirmed by other nodes.
Not to say that cryptocoins have no under-the-matress advantages. They are a lot easier to hide than cash and you can make backup copies of them, which obviously can't be done with cash.
The fix is checking all inputs/outputs rather than relying on the transaction hash.
Edit: Here is a good explanation of what this latest problem is which is different than the problem MtGox is struggling with http://www.reddit.com/r/Bitcoin/comments/1xm49o/due_to_activ...
People are making the case (and I tend to agree) that Gox should have contacted the other exchanges in private to discuss this problem before going public with it.
There's a very good chance this widespread attack is a direct result of Gox's announcement.
I believe the change was made in release 0.8.6
Day two: Uhh... "Stay calm. This is just the expression of that non-issue looking like an issue. We know what we're doing."
Bitcoin has, generally, intrinsic crash protection right now. The price can't plummet if you can't find trading partners. Nobody really knows the price. The dotcom crash was from lofty to zero. As the price eats through panic sell thresholds, pants are shat. At least with commodities, people can point to the ones that went to 0 and stayed there. Since it hasn't happened with bitcoin, people can still sing the "it always bounces back" tune.
I've kicked the dead horse of stability. I've hinted at liquidity issues, but this is a grave lack of liquidity. The only thing left is any belief that there is value. If that starts to deteriorate due to the other issues, poof
Not to mention... the primary exchanges seem to produce that sort of clunky, bug-riddled system that undermines my confidence. A derivatives exchange? So, what the come-latelies are working on? They ain't even no Satoshi.
But sadism is very rare, in reality. Most robbers don't give the rubies they steal to the village children. Most galloping animals with four hooves are horses, not zebras.
But the power of the internet can magnify the effect of a single sadist to the point that it affects a million people (up to the limited extent that such opportunities exist).
Just my thoughts
I'm new to this but maybe we need to make it easier to move money from wallet to wallet, from wallet to "hard" currencies and back, etc. Right now it's practically impossible to get verified on an exchange, get money out, paying anywhere with it, etc. You are lucky if you have a bitcoin ATM where the rate is probably not that good but at least you can get some coins without sending your passport to an unknown exchange half across the world.
Without Bitcoin reaching in the real world faster, I'm not sure what strategy to employ to give it any value in the long run, making it more volatile too...
Though I profited strangely last Saturday when ponzi.io screwed up and gave me a ~96x payback, Ponzi/Casino/etc schemes which may in a way help market BTC through ensuing media frenzy, are still mostly detrimental while they are the majority of the currency's activity.
So, maybe we need to simplify software and make them all more compatible, through exported private-keys, etc. Why do I have to pay a fee by paying myself to move my money from my computer to my cell phone, for example...
How can any store expect to be paid in Bitcoin? Does he have to wait 6 verifications before letting the client go? Should we pay when we arrive and trust the store for the change? Maybe then we can have an Escrow service, 3 key involved, to vouch for those short term transaction but then aren't we back to the banking problem?
Is anyone working on a wallet that is compatible with import/export and that grandma can use? :)
Thank you Captian Obvious!
To build something easier, you'd probably need to "hide" Bitcoin and just present a balance and a simple way of associating "contacts" (with enclosed addresses).
It's a non-issue in so far as it does not prevent bitcoin from working as it should if you do implement things as the original client does it, it's only an issue because it's something you might easily get wrong when implementing a new client (which apparently happened to some other developers), and it would have been avoidable - but changing the behaviour now has to be done very carefully, coordinating with all implementors of bitcoin clients, in order to make sure the fix does not cause a blockchain split, so that is what is happening.
This is not correct. The original client gets one edge case wrong and it is this that is causing the issue with most of the exchanges that use it: http://www.reddit.com/r/Bitcoin/comments/1xm49o/due_to_activ...
It is not "lose money" exploitable (unless combined with social engineering) but is definitely "lose time, lose effort" exploitable.
Not to be an excuse for the consistent problems with MtGox, but everyone who is affected by the current DDoS attacks should just shut the f..k up.
The drama isn't because of bitcoin, it is because it is the first cryptocoin breaching new markets consistently. So as it treads new ground there will always be resistance.
Better to get these bugs out of the way now than in two years when market cap is much greater.
Basically the reference client allows an edge case where it allows spending an unconfirmed output if that output was generated by the wallet itself as change. This can form a chain of unconfirmed transactions. When the malleable bot modifies the original one they all become invalid. The reference client does not handle this case well, it gets balances wrong, and clogs the wallet up.
It's unfortunate that Mt Gox got a lot of heat for calling out the issue from the foundation and core developers saying that malleability was known and wasn't a bit issue. in fact it is an issue due to this edge case in the reference client.
Assuming equal reach for would-be-sellers and would-be-buyers, more buyers are capable of expressing their opinion in the market than are sellers.
Is it unreasonable? No. Is there any evidence to suggest it? No.
>The first form of malleability is in the signatures themselves. Each signature has exactly one DER-encoded ASN.1 octet representation, but openssl does not enforce this, and as long as a signature isn't horribly malformed, it will be accepted. In addition for every ECDSA signature (r,s), the signature (r, -s (mod N)) is a valid signature of the same message.
> [...]I'm a bit hesitant to bake in assumptions about malleability when we have no solid idea if ECC signatures are or are not malleable on a fundemental level; if "whack-a-mole" anti-malleability is all we've got it could be ugly if a break is found.
I understand this to mean, there may be unknown ways to transform signatures, like the s sign flip you quoted. In that case there would be no way to know which representation is "canonical." Thus, malleability is either a fundamental, fatal flaw in Bitcoin, or just something Bitcoin developers need to work around.
Now, it seems even the reference implementation isn't perfect about malleability, and perhaps people could have been better about making the issue known. So there is work to be done, but it is not a "bug" that can be "fixed", at least not without upgrading the entire network, and/or risking it popping up in the future when someone applies more ECDSA signature mutation tricks. The real solution, if you want to safely fingerprint transactions, is to make your own transaction hash that is immune to malleability, like [2].
[1] http://sourceforge.net/mailarchive/message.php?msg_id=319546...
[2] https://github.com/sipa/bitcoin/commit/e7853a91cf646a6a47011...
I think it would be the first JB movie that has a chance of not being out-of-date tomorrow.
Maybe foreign government? Heck, domestic government?
Not, in general, true. You could rent thousands of botted-up consumer-grade PCs located in the United States to run your custom bitcoin client for hundreds of dollars. This particular attack doesn't require any detailed computation -- all you have to do is observe a transaction broadcast from Legitimate Node N1, perform nanoseconds of computation on it, and broadcast the resulting transaction from your Conspiring Nodes N2...N1000 faster than N1 does. Assuming you do, your altered transaction will be the one adopted by the consensus, not the original one.
The technical complexity of this attack is substantially below several levels of e.g. the Stripe CTF event, which were designed to be implemented by intermediate programmers in a few hours of play.