Is there anywhere transcripts I can look at? In the matter of taint I think it's an either or issue. Either taint is something to be handled or nothing is to be done at all. If it is going to be addressed it will likely fracture bitcoins into some sort of two tiered legal and illegal bitcoins. It should come to the forefront fairly quickly though in Mr Trendon Shavers case.
Developer Maxwell is a strong proponent of mixing to preserve privacy, and of the necessity of fungibility to preserve the health of bitcoin. He also has a thread titled "I taint rich" that gives some deeper insight into transactions and the current ideas of taint.
I find his arguments persuasive, but I also find myself deeply unhappy about the theft issue. Before I studied his arguments, I developed the following scenario. This is a broad brush concept, the devil & his details have not yet been subjugated.
I have tried to find a scenario where miner's make clean coins, theft is reported to the block chain, the original victim gets restitution, bad guys can't benefit from false theft reports, and most coins are clean.
A claim of stolen coins could be made by sending a payment from the stolen address to a well known address 1Stolenwhatever, another payment to the theft receipt address, and change to an address
with a public comment giving the TXid of the theft. The payment to the theft receipt address is important so that they have (legal) notice of the theft claim. A simultaneous transaction would deposit coins into the stolen address.
In the case of coins that are stolen, I would assign (a user defined) value to the stolen inputs to the theft transaction, e.g., "0"
I would then trace all the inputs to the transaction being considered starting from freshly generated bitcoins. That transaction would have a face value input, and a "tainted value" input. All outputs from that transaction would carry the weighted value of output.
Please notice that inputs from the compromised address before the theft transaction carry their full value.
Any transactions in the block with the notice are still "clean."
By choosing coins that have a large number of confirms (a possible wallet source change), it is very unlikely that stolen coins will be propagated quickly, so exposure of innocent bystanders is minimized.
Now, there is a policy decision.
I would force a miner's fee to a tainted transaction.
Inputs that are 1 transaction after the notice forfeit 10% of the taint value to the miner's fee. Thus miners have incentive to adopt this policy.
The new address receives half of this miners fee as new coins, so the miner and the victim split this insurance payment.
The taint of the outputs is re-calculated to account for the amount of restitution (not including the miner's fee).
So, in time, the victim gets restitution, miner's are paid for protecting bitcoins, the theft victim gets to report coins as stolen, and old coins are presumably clean and can be spent with confidence.
It might be necessary to reduce the amount of restitution if the victim does not make a prompt report. For example, we don't want coins reported as stolen 5 years after the theft.
This is not a polished solution, and the numerical amounts need to be adjusted. I do think it is a good starting point.
Your ideas are good.
If we have taint capabilities does the community get to vote and decide which coins are and aren't tainted? What if there is a dispute about whether the coins are stolen or not? How can we maintain the decentralized and democratic mechanism of Bitcoin and avoid situations where the political atmosphere in a specific nation results in coins being tainted for political reasons because a prosecutor says so (like in the case of Wikileaks and Paypal).
Additionally what is your opinion on the use of time lock encryption to reduce the possibility of unjustly confiscating coins? If the coins are locked in time then they cannot be confiscated by the government until the time limit is up even if the government were to torture the individual and retrieve the password. This could allow an individual dissident under a certain political environment to lock their coins up and wait for the laws to change in their favor as society becomes more enlightened.
The coins would essentially be locked up in the blockchain itself. Another feature could be setting coins so that out of a wallet the coins can only be spent at a certain rate over a certain period of time. It may even be possible to configure a wallet with features to lock down or do a dead mans switch if certain recurring transactions are not made in a certain sequence.
If the wallet is completely emptied within an hour then the coins are considered stolen if the user defines this scenario as something they would never do. Allow the user to set different parameters for their wallet through scripting and you can make theft more difficult. Additionally the time release functionality could make scams more difficult because the coins cannot be spent until a certain period of time passes or can only be spit at a certain user defined rate. This would not completely prevent scams but it would make the scams more time consuming to pull off and give people more time to uncover the scam.
I still don't see any viable technical solution to dealing with money laundering and terrorist finance possibilities. If Bitcoin is going the anonymous transactions route then an alt coin can experiment with taint and blacklist procedures to find out if it can work or not. A simulation can be conducted where a contest can be held to see if anyone can trace a transaction which has been mixed or to role play a scenario where a team of terrorists are trying to finance something and then let another team roleplay trying to stop them. The result of this role play could be used in an academic research paper to determine whether or not the threat of terrorist finance is a realistic possibility.
If it's a real threat then my opinion is we have to create the tools to mitigate the risks. If it turns out it's not a real threat then it's not a problem. But I don't think we can avoid doing the simulations and research because we have to know what the risks are if we want to regulate cryptocurrencies ourselves through technical means.