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

[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?

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.

Agreed. I think focus should be put on FUNGIBILITY of bitcoin and not block size increase.

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[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.

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?

I believe there are some users that just dont know any better and they send their clean coins to a mixer thinking "hey I can be more anonymous with my purchases"...and then get dirty coins instead.

[mallard]

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.

I'm not sure about other wallets, but in Bitcoin-qt you can enable "coin control features" and select which inputs you want to spend.

[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?

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?

if blacklisting/whitelisting becomes more and more applied, some wallets will offer the option to avoid using this "taint spam"

[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?

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 problem is that government regulation and self-censorship will controll what you will be able to do with your bitcoins.
So indeed, I agree with you... Bitcoin isn't money.

[dnaleor]

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?

as far as I know, the answer is no.
at least... not yet.

[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.

I'm not sure about other wallets, but in Bitcoin-qt you can enable "coin control features" and select which inputs you want to spend.

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

[dnaleor]

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.

people will stop using payment processors when businesses stop using payment processors.
That will only happen when bitcoin is much much less volatile and much much more liquid.

In other words, that will only happen when the critical mass is reached.
Conclusion, fungibility will be an issue for BTC until critical mass is reached.

=> We need to ask our self the question if a token that isn't fungible has the ability to reach critical mass.

[dnaleor]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

[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.
 

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.

I'm not sure about other wallets, but in Bitcoin-qt you can enable "coin control features" and select which inputs you want to spend.

Wallets often try to hide the details, but txouts are the only things that are spent in bitcoin transactions.

In bitcoind (or in the QT debug console) a transaction can be created using "createrawtransaction". For example, to create tx spending one tx out to one address it would look like this:

createrawtransaction '[{"txid":"abc...[longtxhashinhex]...0af","vout":1}]' '{"1BitcoinAddress":100.0}'

This spends the output 1 (the second, since output 0 is the first) of the tx with id "abc...0af". It creates one new txout which will be output 0 of this new tx after its signed, relayed and confirmed. This new txout can be spent by creating a new tx that spends this txout as one of the output. It would need to be signed by the private key for "1BitcoinAddress" (which isn't a real Bitcoin address,  of course).

More information about transactions is at the bitcoin wiki page:

https://en.bitcoin.it/wiki/Transaction

[RGBKey]

If people start trying to blacklist coins I will do everything in my power to stop them and I suggest everyone else do the same because blacklisting would harm bitcoin beyond anything we've seen so far.

[smooth]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

You can separate them until the two are spent together, since they are separate outputs as explained in the last few posts. Once they are spent together, they can't be separated.

What I expect will likely happen in a system with widespread regulation and blacklist once they are mixed (spent) together is that you would then have to send the 1.0 to some government (or other third party service) address, along with your identifying information, and you would get the 0.5 clean back.

[smoothie]

If people start trying to blacklist coins I will do everything in my power to stop them and I suggest everyone else do the same because blacklisting would harm bitcoin beyond anything we've seen so far.

That would help your peers or people you are in communication with. But not everyone.

You can't stop black listing.

It's kind of in the gray area. I isn't in full force but it isn't something you can just squish (unless we are talking major bitcoin protocol code changes).

[RGBKey]

If people start trying to blacklist coins I will do everything in my power to stop them and I suggest everyone else do the same because blacklisting would harm bitcoin beyond anything we've seen so far.

That would help your peers or people you are in communication with. But not everyone.

You can't stop black listing.

It's kind of in the gray area. I isn't in full force but it isn't something you can just squish (unless we are talking major bitcoin protocol code changes).

You can fight it by boycotting any service that uses or supports blacklisting coins. That much is within your power.

[smoothie]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

You can separate them until the two are spent together, since they are separate outputs as explained in the last few posts. Once they are spent together, they can't be separated.

What I expect will likely happen in a system with widespread regulation and blacklist once they are mixed (spent) together is that you would then have to send the 1.0 to some government (or other third party service) address, along with your identifying information, and you would get the 0.5 clean back.

This is a pretty good thing to know especially if a thief tries to taint your bitcoins with small micro amounts. If you send it to an exchange where it combines the tainted coins with your bitcoins then now the coins are indistinguishable.

I can see a mechanism that payment processors may (with a grain of salt type of "may") just take the portion that is tainted and send it off to a government wallet and the rest would be "all clear" to use.

But there are so many levels of this topic that I'm unsure what the implications would be.

Too many unknowns

[smoothie]

If people start trying to blacklist coins I will do everything in my power to stop them and I suggest everyone else do the same because blacklisting would harm bitcoin beyond anything we've seen so far.

That would help your peers or people you are in communication with. But not everyone.

You can't stop black listing.

It's kind of in the gray area. I isn't in full force but it isn't something you can just squish (unless we are talking major bitcoin protocol code changes).

You can fight it by boycotting any service that uses or supports blacklisting coins. That much is within your power.

Yes, but in a limited space (ecosystem wise) currently, boycotting any business that is a major player in the space does limit your ability and others to transact with bitcoin.

You basically take those businesses off of your list to do deals with. Essentially limiting your options even more.

Hopefully this wont be a wide spread problem. As if it gains traction I can see boycotting being irrelevant especially if most large BTC businesses start implementing blacklists.

[RGBKey]

If people start trying to blacklist coins I will do everything in my power to stop them and I suggest everyone else do the same because blacklisting would harm bitcoin beyond anything we've seen so far.

That would help your peers or people you are in communication with. But not everyone.

You can't stop black listing.

It's kind of in the gray area. I isn't in full force but it isn't something you can just squish (unless we are talking major bitcoin protocol code changes).

You can fight it by boycotting any service that uses or supports blacklisting coins. That much is within your power.

Yes, but in a limited space (ecosystem wise) currently, boycotting any business that is a major player in the space does limit your ability and others to transact with bitcoin.

You basically take those businesses off of your list to do deals with. Essentially limiting your options even more.

Hopefully this wont be a wide spread problem. As if it gains traction I can see boycotting being irrelevant especially if most large BTC businesses start implementing blacklists.

There are very few bitcoin services currently that do not have at least one alternative.

[jonald_fyookball]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

You can separate them until the two are spent together, since they are separate outputs as explained in the last few posts. Once they are spent together, they can't be separated.

What I expect will likely happen in a system with widespread regulation and blacklist once they are mixed (spent) together is that you would then have to send the 1.0 to some government (or other third party service) address, along with your identifying information, and you would get the 0.5 clean back.

That would be the end of bitcoin, since there's going to be some amount of taint going on almost all the time.  Can't see it happening.

[RGBKey]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

You can separate them until the two are spent together, since they are separate outputs as explained in the last few posts. Once they are spent together, they can't be separated.

What I expect will likely happen in a system with widespread regulation and blacklist once they are mixed (spent) together is that you would then have to send the 1.0 to some government (or other third party service) address, along with your identifying information, and you would get the 0.5 clean back.

That would be the end of bitcoin, since there's going to be some amount of taint going on almost all the time.  Can't see it happening.

Agreed, you will get people that are unlucky and receive coins from an exchange that did not support blacklisting, and then that user will have effectively lost money.

[smooth]

I wasn't aware of that.  I assume that only goes one level deep.  In other words, if I have stolen coins (.5 BTC) and normal coins (.5 BTC)
and I send that to another address of mine, and then send you 1 BTC, you can't separate out the stolen coins from the normal coins.

that is true indeed.

You can separate them until the two are spent together, since they are separate outputs as explained in the last few posts. Once they are spent together, they can't be separated.

What I expect will likely happen in a system with widespread regulation and blacklist once they are mixed (spent) together is that you would then have to send the 1.0 to some government (or other third party service) address, along with your identifying information, and you would get the 0.5 clean back.

That would be the end of bitcoin, since there's going to be some amount of taint going on almost all the time.  Can't see it happening.

Agreed, you will get people that are unlucky and receive coins from an exchange that did not support blacklisting, and then that user will have effectively lost money.

So effectively you are saying that if people using an unregulated exchange that is not compliant they will lose money, and therefore the end of Bitcoin? Is that really what I just read?