Illegal Content and the Blockchain

schneier.com

12 pointsjoe_the_user3 comments

As of today, one can write up to 83 bytes in an OP_RETURN output. This means all data files are fragmented into at most 83 bytes, surrounded by other bitcoin script, sigs and tx input references. They are not sitting around on disk in file form.

The blocks also contain things like the EICAR string that will cause AV software to delete block files. To combat this, all bitcoin blocks are obfuscated (encrypted and store the key next to it) with a per node key at rest.

I find it hard to believe that there isn’t Falun Gong text on the Bitcoin blockchain already. There certainly will be soon, now.

This was slightly glossed over in the article. The decisive responses to discovering unwanted content all depend on discovering it quite quickly. If encrypted Falun Gong or Disney content was added in 2017, and the key made public today, there are definitely fewer options available.

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