Eventually the FUNGIBILITY issue of bitcoin will make headlines ...

[Biodom]

The problem with having a transparent blockchain is the lack of fungibility. This is way gmaxwell is working hard on features like confidential transactions. We NEED to improve the anonymity on Bitcoin before it goes mainstream. You don't want people's money being rendered useless because of a lottery based on the origin of said money (if its legit or if it has a trace of some criminal activity which you had no idea and no control of).

Stop conflating two very different issues. Privacy/traceability != fungibility

The two are in practice almost identical unless you are giving identifying information only to a privileged party (bank, government, etc.) in which case fungibility may exist at the discretion of that entity, or fungibility is enforced (by law). The former is certainly not the case in Bitcoin and likely never will be. The latter is theoretically possible but unlikely. If the units have a visible and distinct history that has at least the possibility for them to become non-fungible since actors may attach importance to properties of that history.

This has already happened in Bitcoin with actors such as Coinbase and apparently now Bitpay identifying coins by a "good" or "bad" history. Whether this will become more or less common is a matter of speculation, not the properties of the system itself. That the properties of the system can give rise to these issues is proven by experience.

well, it depends on how much effort goes into it.
one can lift fingerprints off the #20 bill, analyze chemical residue on it, etc., however, apart from criminal cases, nobody does this.
In my opinion, it is somewhat imperative for bitcoin to become fungible and to incorporate some tech to do it at the protocol level.
Trace Mayer was talking about this: apparently Messrs Back and Maxwell were ready to introduce this before all this blocksize nonsense came about.

[smooth]

well, it depends on how much effort goes into it.
one can lift fingerprints off the #20 bill, analyze chemical residue on it, etc., however, apart from criminal cases, nobody does this.

Yes and there is an enormous difference in difficulty and practicality (and also likely effectiveness) between doing that and querying a database of risk scores fed from a public blockchain (and other sources). Big data is upon us and the data in Bitcoin isn't even that big.

Which of course explains why as you say nobody analyzes paper money but Coinbase and apparently Bitpay and probably others are certainly analyzing the blockchain. That and legal differences (I think already covered on this thread or maybe elsewhere recently).

[dnaleor]

Everyone's spent outputs combined with everyone's spent outputs? Not all the time.

LIke I said in the OP there will come a day when a new user will buy bitcoins (say locally for cash) and when he goes to use them at a business or exchange or where ever they will be rejected. Not 100% of the time...but it will happen and we all know how the media today loves to jump on anything bitcoin related that is negative.

Please reference the OP as it was a prediction and just that.

Ok, I'll grant you that, but is it really a big deal if it outputs aren't combined "all the time"? 
The people that have the "hottest" Bitcoins are obviously going to go to the most trouble to
mix and detaint them...and they do that already not because of blacklisting, but because
they need to remain anonymous and stay out of jail for theft.

It's not about ANONIMITY, it's about FUNGIBILITY

You can try to be (somewhat) anonymous on the BTC network, but that doesn't mean the coins are fungible

Ask yourself...
If you earn a legal income in BTC, will you voluntarily mix your coin with criminals?

[jonald_fyookball]

Everyone's spent outputs combined with everyone's spent outputs? Not all the time.

LIke I said in the OP there will come a day when a new user will buy bitcoins (say locally for cash) and when he goes to use them at a business or exchange or where ever they will be rejected. Not 100% of the time...but it will happen and we all know how the media today loves to jump on anything bitcoin related that is negative.

Please reference the OP as it was a prediction and just that.

Ok, I'll grant you that, but is it really a big deal if it outputs aren't combined "all the time"? 
The people that have the "hottest" Bitcoins are obviously going to go to the most trouble to
mix and detaint them...and they do that already not because of blacklisting, but because
they need to remain anonymous and stay out of jail for theft.

It's not about ANONIMITY, it's about FUNGIBILITY

You can try to be (somewhat) anonymous on the BTC network, but that doesn't mean the coins are fungible

Ask yourself...
If you earn a legal income in BTC, will you voluntarily mix your coin with criminals?

Yeah I agree with you.

My point was that threats to fungibility due to blacklisting are probably a non issue
because spent outputs are always getting combined, ESPECIALLY when there are bad actors.

[brg444]

Everyone's spent outputs combined with everyone's spent outputs? Not all the time.

LIke I said in the OP there will come a day when a new user will buy bitcoins (say locally for cash) and when he goes to use them at a business or exchange or where ever they will be rejected. Not 100% of the time...but it will happen and we all know how the media today loves to jump on anything bitcoin related that is negative.

Please reference the OP as it was a prediction and just that.

Ok, I'll grant you that, but is it really a big deal if it outputs aren't combined "all the time"? 
The people that have the "hottest" Bitcoins are obviously going to go to the most trouble to
mix and detaint them...and they do that already not because of blacklisting, but because
they need to remain anonymous and stay out of jail for theft.

It's not about ANONIMITY, it's about FUNGIBILITY

You can try to be (somewhat) anonymous on the BTC network, but that doesn't mean the coins are fungible

Ask yourself...
If you earn a legal income in BTC, will you voluntarily mix your coin with criminals?

You might not have a choice.

What are you going to do if I'm a criminal and decide to "taint" your Bitcoin by sending bits to your wallet? Sell your bitcoins?

[Biodom]

Everyone's spent outputs combined with everyone's spent outputs? Not all the time.

LIke I said in the OP there will come a day when a new user will buy bitcoins (say locally for cash) and when he goes to use them at a business or exchange or where ever they will be rejected. Not 100% of the time...but it will happen and we all know how the media today loves to jump on anything bitcoin related that is negative.

Please reference the OP as it was a prediction and just that.

Ok, I'll grant you that, but is it really a big deal if it outputs aren't combined "all the time"?  
The people that have the "hottest" Bitcoins are obviously going to go to the most trouble to
mix and detaint them...and they do that already not because of blacklisting, but because
they need to remain anonymous and stay out of jail for theft.

It's not about ANONIMITY, it's about FUNGIBILITY

You can try to be (somewhat) anonymous on the BTC network, but that doesn't mean the coins are fungible

Ask yourself...
If you earn a legal income in BTC, will you voluntarily mix your coin with criminals?

if bitcoin is not fungible, then it is not money, it is as simple as this
BTW, marshals sold tainted bitcoin from silk road and someone (silicon valley VCs, etc) bought them.
I don't think that this bitcoin is tainted anymore de facto, but if you look at these coins history, it would look pretty bad, right?
If bitcoin IS money, then it cannot be at fault what someone did with it any more than you cannot control what someone did with a $20 bill.

[ArticMine]

...

You might not have a choice.

What are you going to do if I'm a criminal and decide to "taint" your Bitcoin by sending bits to your wallet? Sell your bitcoins?

It would actually make economic sense for a criminal holding a large amount of tainted Bitcoins to do just that with a portion of the tainted Bitcoins.

[Trent Russell]

What are you going to do if I'm a criminal and decide to "taint" your Bitcoin by sending bits to your wallet? Sell your bitcoins?

I'm guessing you mean send some bits to one of his addresses. I suspect "taint" applies to txouts rather than addresses. He can avoid "tainting" his bitcoins with your bits by simply never spending your txout -- even though he has the private key.

Your comment reminded me of something you wrote earlier and quoted at the beginning of the thread:

Let's pretend I have one of Satoshi's wallet address and decide to send him a bitcoin. How can you tell which one is mine from his stash?

I can distinguish them very easily. The one from his stash was generated from the coinbase tx of an early block. The one you sent him is the txout of a much later tx spending some bitcoins you controlled.

An entire public history corresponds to each txout. These histories can be used to distinguish between txouts. That's why txouts are not fungible. This statement is often reasonably simplified to "bitcoins are not fungible."

[bitcoinrocks]

For privacy, I use blockchain.info's SharedCoin (a type of mixer) to avoid linking my BTC spends/transfers to my main wallet.  Has there been any indication that using a service like that could prevent a company from being willing to transact with you?

Of course, if the answer is no, this brings to mind a question like: why wouldn't a person with BTC from an undesirable source just use a mixer?

[jonald_fyookball]

What are you going to do if I'm a criminal and decide to "taint" your Bitcoin by sending bits to your wallet? Sell your bitcoins?

I'm guessing you mean send some bits to one of his addresses. I suspect "taint" applies to txouts rather than addresses. He can avoid "tainting" his bitcoins with your bits by simply never spending your txout -- even though he has the private key.
 

huh?

I'm confused.  Maybe I don't understand Bitcoin transactions well enough.   

I thought once incoming transactions reach the Bitcoin address, you can either spend them or not -- you don't
get to say which of the inputs of other parties count toward your transaction.  If I'm wrong, please explain.

[smoothie]

 https://www.reddit.com/r/Bitcoin/comments/374ss5/the_problem_with_bitcoin_that_everyone_seems_to/

My thesis is that the transparent nature of the Bitcoin Blockchain leads us to the path of (nasty) government regulation.

This won't be some long theoretical opinion about technical Bitcoin flaws, I will provide you with some clear practical examples. People who love to have extensive government regulation, please move on and ignore this post.

What is exactly problematic about a transparent blockchain? Well, every UTXO has a history. This means mainly 2 things:

1) people who receive a transaction can see this history

2) miners who put transactions into blocks can see this history

Let me be clear. The issue we are talking about here isn't anonymity, it's fungibility.

You can try to hide your coins as much as you want, if you tried to mix your coins using a mixer, coinjoin or another type of "anonymity enhancing feature", we will at least be able to detect that you did. We maybe won't know who you are, but those coins can be flagged as "possible suspicious activity on the blockchain".

So what's the big deal about that? Well, this gives governments the possibility to regulate BTC transactions. Let me explain: Basically it comes down to these 2 possible scenario's: blacklisting and whitelisting

Government could on one hand through “whitelisting” obligate bitcoin users to identify themselves when they purchase bitcoins (this is already happening: KYC and AML) and ask them to whom they are transferring these bitcoins (Coinbase is already asking this for some transactions).

In the future this could lead to a situation in which only “identified” bitcoins would be spendable at regulated payment processors. Every business that accepts bitcoin in a certain jurisdiction would need to use a certified payment processors that only accepts "whitelisted" coins.

As a result, your anonymous bitcoins would only be spendable if you match them to your identity through a regulated authority (exchange, wallet service or directly through government). If you try to spend other coins, the payment processor could send them back you you (best case) or send them to a government wallet (worst case) and maybe you can claim the coins after you identify yourself (at least you have your coins back...)

A more aggressive approach is “blacklisting”. This is a system whereby the government makes it illegal to process certain blacklisted UTXO's.

Of course you would say that no miner would comply... But think about it. Would a large mining farm operator risk going to jail for "money laundering" or will he comply? After all, he has electricity bills to pay. The profit will be more important than the ideology.

This kind of regulation leads to a loss of fungibility. Bitcoin isn't fungible anymore if one bitcoin is accepted for payment or isn't mined anymore and another isn't.

If you are thinking that i'm exaggerating because there are a lot of jurisdictions and there will always be places where there will not be this strict regulation, you are right.

But it gets worse...

Not only governments but even companies will start to apply regulation by themselves as a form of self-censorship, because they fear government crackdown on their business:

We already saw the "whitelisting version" with the deposit of the Evolution coins to BTC-e. Those coins weren't allowed by an exchange that is pretty anonymous themselves! The reason is that they don't want the CIA and Europol on their doorstep, so they decided not to accepts possible money laundering activity.

And what about the blacklisting by the miners? I'm sure there will be ideologically motivated miners that will keep processing blacklisted UTXO's.

But there are far less pools than there are individual miners. The regulation will slowly affect this. I see a 5 stage system:

A. there will be some pools that voluntarily adopt the regulations, because they fear government crackdown (same situation as BTC-e with the Evolution coins)

B. some miners fear the government, so they ask their pool operators if they will comply with the regulations. If not, they move to a "regulated pool". It will slowly become a disadvantage for pool operators to not comply. If one uses mixed bitcoins, the transactions will start to suffer from delays because of less miners processing them.

C. the regulation will become more harsh. Building on a block that contains blacklisted transactions will become illegal. This will lead to more pools censoring themselves because they fear they will loose the block reward if they don't comply

D. the "illigal block depth" will become larger (f.e. not building on a chain which 3 blocks "deep" had a blacklisted transaction; more pools start to comply

E. almost everybody now complies and blacklisted UTXO's won't be spendable unless they pass through a regulation authority.


In essence this could lead to three kinds of bitcoins:

1. White bitcoins: bitcoins that satisfy the identification regulation.

2. Grey bitcoins: bitcoins that are not yet identified, but which are not actively anonymized. transactions are allowed, but not spending them at a certified payment processor.

3. Black bitcoins: bitcoins that are banned by miners. Processiing them is illegal. Maybe even owning them...

The consequence?

Bitcoin will not be fungible anymore: you can’t just use a grey or black bitcoin to buy something from a webshop. If the government is able to discover that you possess black bitcoins or process blacklisted type transactions, you could even be seen as a someone committing a crime.
Eventually Bitcoin will become a fast payment system without counterparty risk but with full government control.
Is that what we really want?
And if you think these are all unlikely scenario's then well... we will talk again in 5 year's time.

[dnaleor]

It would help if you were a big time miner and minted your own fresh coins, where you develop some kind of way to mix your own coins with your brand new ones... other than that particular instance, I don't see mixers or stuff of the like being very helpful.

interesting, a "white mixer" for non-suspicious coins.
To be used if you want some anonymity, but don't want to mix with dirty coins.

This mixer would off course check if the incoming transactions are from darkmarkets, other "black mixers" etc
so they don't get shit making their mixer dirty.

[dnaleor]

Pretend a well-known thief was committed via bitcoins to the tune of millions of dollars (I know, it's a stretch, but let's pretend nonetheless). The crime was reported to authorities, thus anybody having direct information pertaining to the crime but fails to report their findings would, in fact, be committing a crime themselves. Follow me so far?

Enter BitPay.

Tainted coins were presented to BitPay (read: I present to you evidence of a very bad crime), but they turn the customer away (read: Thanks, but we don't want no part of this). At this point, BitPay is privy to evidence related to a major heist. It's bad enough if they just let the entity go with a "Thanks, but no thanks!" as per their new public stance on the taint issue, but they now would put their very existence in jeopardy if they opted to not report the evidence to the proper authorities themselves. But, if they do report each and every suspected instance to the authorities, as they must, that would 100% be badder for them and Bitcoin, the latter self-explanatory, while the former would consist of doling out resources so to not be in foul with authorities spanning the globe (not just in the US). Demanding resources that BitPay has demonstrated they no longer have.

BitPay just announced to the world that they would not accept tainted coinage. Genius! Now that they have demonstrated to authorities that they possess the means to help track criminals, they've put themselves in positions to 100% having to follow through with each and every suspected transaction by not only rejecting the coins, but turning in the suspects sans letting them know that that's the case, for you don't tell suspects that they're goin' be reported. YOU JUST DO IT!

And that's how you destroy your venerable brand in ONLY a few short days. Again, GENIUS!

I suspect there will come a day that a regulated payment processor will be required to send the tainted coins to a government wallet.
If you are lucky, you can claim your coins back when you provide identity information and the source of the coins
if you are unlucky, the government will put you in jail and you loose your coins.

[smoothie]

Everyone's spent outputs combined with everyone's spent outputs? Not all the time.

LIke I said in the OP there will come a day when a new user will buy bitcoins (say locally for cash) and when he goes to use them at a business or exchange or where ever they will be rejected. Not 100% of the time...but it will happen and we all know how the media today loves to jump on anything bitcoin related that is negative.

Please reference the OP as it was a prediction and just that.

Ok, I'll grant you that, but is it really a big deal if it outputs aren't combined "all the time"?  
The people that have the "hottest" Bitcoins are obviously going to go to the most trouble to
mix and detaint them...and they do that already not because of blacklisting, but because
they need to remain anonymous and stay out of jail for theft.

It's not about ANONIMITY, it's about FUNGIBILITY

You can try to be (somewhat) anonymous on the BTC network, but that doesn't mean the coins are fungible

Ask yourself...
If you earn a legal income in BTC, will you voluntarily mix your coin with criminals?

if bitcoin is not fungible, then it is not money, it is as simple as this
BTW, marshals sold tainted bitcoin from silk road and someone (silicon valley VCs, etc) bought them.
I don't think that this bitcoin is tainted anymore de facto, but if you look at these coins history, it would look pretty bad, right?
If bitcoin IS money, then it cannot be at fault what someone did with it any more than you cannot control what someone did with a $20 bill.

The Feds selling SR bitcoins for them means they can do what they want.

They can "wash clean these bitcoins because we are so holy in the bitcoin space"....that they were sold as a legitimate purchase.

In their eyes because they seized those coins because of illegal drug sales etc, by doing just that, now everyone knows those coins are coming from an official authority which by default "makes them clean". Yeah I know it's hypocrisy at its finest.

[smoothie]

...

You might not have a choice.

What are you going to do if I'm a criminal and decide to "taint" your Bitcoin by sending bits to your wallet? Sell your bitcoins?

It would actually make economic sense for a criminal holding a large amount of tainted Bitcoins to do just that with a portion of the tainted Bitcoins.

"now everyone is a criminal!" lol

Well my perspective is that the idea will be to "follow the money"...Just because A THIEF sent $0.0000001 worth of BTC to your address probably doesn't mean much..

But if I sent 10 BTC or 50BTC or 10000 BTC then it gets more interesting.

That threshold of relevance will be determined by our overlords lol

[jonald_fyookball]

Pretend a well-known thief was committed via bitcoins to the tune of millions of dollars (I know, it's a stretch, but let's pretend nonetheless). The crime was reported to authorities, thus anybody having direct information pertaining to the crime but fails to report their findings would, in fact, be committing a crime themselves. Follow me so far?

Enter BitPay.

Tainted coins were presented to BitPay (read: I present to you evidence of a very bad crime), but they turn the customer away (read: Thanks, but we don't want no part of this). At this point, BitPay is privy to evidence related to a major heist. It's bad enough if they just let the entity go with a "Thanks, but no thanks!" as per their new public stance on the taint issue, but they now would put their very existence in jeopardy if they opted to not report the evidence to the proper authorities themselves. But, if they do report each and every suspected instance to the authorities, as they must, that would 100% be badder for them and Bitcoin, the latter self-explanatory, while the former would consist of doling out resources so to not be in foul with authorities spanning the globe (not just in the US). Demanding resources that BitPay has demonstrated they no longer have.

BitPay just announced to the world that they would not accept tainted coinage. Genius! Now that they have demonstrated to authorities that they possess the means to help track criminals, they've put themselves in positions to 100% having to follow through with each and every suspected transaction by not only rejecting the coins, but turning in the suspects sans letting them know that that's the case, for you don't tell suspects that they're goin' be reported. YOU JUST DO IT!

And that's how you destroy your venerable brand in ONLY a few short days. Again, GENIUS!

I suspect there will come a day that a regulated payment processor will be required to send the tainted coins to a government wallet.
If you are lucky, you can claim your coins back when you provide identity information and the source of the coins
if you are unlucky, the government will put you in jail and you loose your coins.

But then people might not like that and stop using payment processors and just deal directly in Bitcoin.
Once a critical mass is reached, people won't need to convert to fiat as much.

[pereira4]

For privacy, I use blockchain.info's SharedCoin (a type of mixer) to avoid linking my BTC spends/transfers to my main wallet.  Has there been any indication that using a service like that could prevent a company from being willing to transact with you?

Of course, if the answer is no, this brings to mind a question like: why wouldn't a person with BTC from an undesirable source just use a mixer?

Mixers are ultimately poor workarounds. You are trusting that the mixer service is not keeping logs. It's a centralized measure. It requires trust, it's not a real solution. Also it's annoying as hell that everytime you use Bitcoin you have to first send it to some mixing service to guarantee privacy. Something needs to be done about this so this privacy is by default in-built in every wallet without needing to trust some mixing company.

[smoothie]

For privacy, I use blockchain.info's SharedCoin (a type of mixer) to avoid linking my BTC spends/transfers to my main wallet.  Has there been any indication that using a service like that could prevent a company from being willing to transact with you?

Of course, if the answer is no, this brings to mind a question like: why wouldn't a person with BTC from an undesirable source just use a mixer?

1. There is risk sending your bitcoins to be mixed.

2. I guess they can do it. Ultimately it doesn't remove the trail of where the bitcoins go. Yes the thief may get away with it but someone will be possibly blacklisted with their coins should those coins be coming form an undesirable source.

[smoothie]

Pretend a well-known thief was committed via bitcoins to the tune of millions of dollars (I know, it's a stretch, but let's pretend nonetheless). The crime was reported to authorities, thus anybody having direct information pertaining to the crime but fails to report their findings would, in fact, be committing a crime themselves. Follow me so far?

Enter BitPay.

Tainted coins were presented to BitPay (read: I present to you evidence of a very bad crime), but they turn the customer away (read: Thanks, but we don't want no part of this). At this point, BitPay is privy to evidence related to a major heist. It's bad enough if they just let the entity go with a "Thanks, but no thanks!" as per their new public stance on the taint issue, but they now would put their very existence in jeopardy if they opted to not report the evidence to the proper authorities themselves. But, if they do report each and every suspected instance to the authorities, as they must, that would 100% be badder for them and Bitcoin, the latter self-explanatory, while the former would consist of doling out resources so to not be in foul with authorities spanning the globe (not just in the US). Demanding resources that BitPay has demonstrated they no longer have.

BitPay just announced to the world that they would not accept tainted coinage. Genius! Now that they have demonstrated to authorities that they possess the means to help track criminals, they've put themselves in positions to 100% having to follow through with each and every suspected transaction by not only rejecting the coins, but turning in the suspects sans letting them know that that's the case, for you don't tell suspects that they're goin' be reported. YOU JUST DO IT!

And that's how you destroy your venerable brand in ONLY a few short days. Again, GENIUS!

I suspect there will come a day that a regulated payment processor will be required to send the tainted coins to a government wallet.
If you are lucky, you can claim your coins back when you provide identity information and the source of the coins
if you are unlucky, the government will put you in jail and you loose your coins.

But then people might not like that and stop using payment processors and just deal directly in Bitcoin.
Once a critical mass is reached, people won't need to convert to fiat as much.

But until then (probably years away)....the issue remains.

[onemorexmr]

For privacy, I use blockchain.info's SharedCoin (a type of mixer) to avoid linking my BTC spends/transfers to my main wallet.  Has there been any indication that using a service like that could prevent a company from being willing to transact with you?

Of course, if the answer is no, this brings to mind a question like: why wouldn't a person with BTC from an undesirable source just use a mixer?

1. There is risk sending your bitcoins to be mixed.

2. I guess they can do it. Ultimately it doesn't remove the trail of where the bitcoins go. Yes the thief may get away with it but someone will be possibly blacklisted with their coins should those coins be coming form an undesirable source.

what  have never understand about mixing: it seems mixing needs a constant flow of "white" bitcoins to mix with. where do they come from?

why does anyone sending their clean coins there and pay a fee for mix them with tainted ones?