Topic: Pruning OP_RETURNs with illegal content - page 2. (Read 4182 times)

All due respect Peter, but being concerned about having illegal data in a system is not absurd and in my opinion it is better to address this issue, because law enforcement certainly will in one way or other. Law enforcement agencies track down and close systems that promote criminal content such as child pornography and I would think that law enforcement will not handle Bitcoin differently when push comes to shove.

You can much more easily publish data via the blockchain w/o OP_RETURN, and furthermore, you can easily put that data in to the UTXO set which all nodes *must* have if they are to maintain consensus.

Mike Hearn suggested we adopt blacklists to solve this problem back when someone put the child porn sections of the hidden wiki into the UTXO set; no-one's come up with a better solution since. You can make publishing that data more expensive by a small linear factor - about 10x to 100x - but that's the best you can do.

The best solution to this problem is legal and political: the idea that you have to prevent every last trace of "illegal data" from getting into a public ledger is absurd.

Just researching another possible threat.
What if an individual who is angry at Bitcoin for whatever reason tries to insert some illegal content into blockchain?
There are a lot of content types that are illegal in one or many jurisdictions, for example Charlie Hebdo cartoons in Pakistan, suicide instructions in Russia, Sony PS3 signing key in the US, etc. This person would inject illegal content into OP_RETURN outputs, maybe spreading large content over several 40 bytes OP_RETURN outputs, and this content would be stored forever. He would inject it in the most open and self evident form possible, no encryption, no steganography, no fancy encoding. The content would be stored and distributed by full node operators. Their activity might not be automatically illegal while they store and distribute this content **unknowingly**. In the pre-blockchain world, it is common practice that if you run a web site that unknowingly stores and distributes some copyright infringing or otherwise illegal content and you receive a take down notice, you comply and you are ok after that. But you can't remove anything from blockchain without destroying its integrity. So a full node operator can only comply by ceasing operations, and if he doesn't comply after receiving a take down notice, he would **knowingly** store and distribute illegal content which places him in bad terms with the law.

This thread https://bitcointalksearch.org/topic/so-what-happens-if-i-violate-the-block-chain-128171 discusses pruning the offending transactions, which is not a simple thing as it would require changes to verification procedures. I understand it was never really necessary and never implemented. Even if it were implemented, it would create a mess if some nodes pruned a transaction while others did not. Also, the inputs of fully pruned transactions could be double spent.

As Bitcoin grows and becomes a business for many, the risks of illegal content become more important.
Any other ideas how to mitigate these risks (if they even exist)?