Quote from: smooth on September 29, 2015, 08:20:49 AM

Quote from: brg444 on September 29, 2015, 07:48:04 AM

Quote from: iCEBREAKER on September 29, 2015, 07:44:57 AM

Quote from: brg444 on September 28, 2015, 08:48:28 PM

Quote from: smooth on September 27, 2015, 10:15:26 PM

losing money due to receiving bad Bitcoin is nothing qualitatively new. I'm not saying it is a good thing though.

"Bad Bitcoin"? Wtf... I know you have some Monero to sell but this is beyond ridiculous

It took me a second, but I now appreciate the #bitcoin-assets 'there are no tainted Bitcoins, only tainted institutions' POV.

I love the smugness of that serene maxim, and look forward to the day when it has practical value for those of us with <100 BTC.

OTOH, I believe (smooth will have to back me up with The Science) that Bitcoins are not perfectly fungible at the protocol level because they are uniquely identifiable, and thus may be discriminated against (ie, considered "bad") by individuals, if not in the aggregate.

AFAIK, the Monero protocol couldn't tell "good" coins from "bad" ones even if it wanted to, so its coins are perfectly fungible (no matter what, and without need to invoke rosy assumptions about the future of crypto vs fiat).

Bitcoin Black/Whitelists: technically trivial to implement and enforce, commonly done in status quo (eg stolen Evolution coins at BTCE)

Monero Black/Whitelists: technically impossible to implement or enforce (is it true?)

I still don't see how that holds true.

As smooth himself has pointed out, once two satoshis are spent from two different inputs to the same output they are indistinguishable.

Coins/satoshis/etc. are not uniquely identifiable as you say, although it is possible to define a rule which would do so. For example, I think some of the colored coin schemes use a rule that if you mix colored and non-colored coins, the colored coins come out in a particular sequence (for example, the first input might directly flow to the first output, etc.). An alternative rule, of course, is that mixing colored and uncolored coins simply destroys the coloring. Both can work. Assuming that people are going to observe a similar convention for regular Bitcoins is a bit contrived but not impossible.

Putting that aside, what exists on the blockchain are not coins but outputs, and outputs are uniquely identifiable because each has a unique history. That is very close to the definition of not being fungible, because fungible means interchangeable. How people choose to interpret that history is again up to them, but we've seen numerous examples of people doing it, so it is implausible to flat out say that people won't do it.

If you want to argue that anyone who tries to implement rules like this will be rendered irrelevant when the crypto singularity comes and fiat fails, and anyone who attempts to pay attention to the unique of different outputs will be laughed at, then I don't necessarily disagree, but mostly I'll just wait to see you on the other side/moon.

For now we have the reality that outputs are very much not fungible. Some can be safely used with Coinbase/Bitpay/etc. and some can not.

I don't even have to go there.

My claim is that anyone that uses Bitcoin as it is meant to be should absolutely not be concerned over fungibility.

Understand that these scarecrows are put in place by third parties attempting to restrict your monetary freedom.

I absolutely disagree with your conclusions, outputs are only non fungible in transactions involving third-parties which is not representative of Bitcoin's design.

Moreover it can certainly be argued that these occurrences are marginal and nothing more than distractions.