Illegal Prime Numbers
There are several past threads of this article but this comment about how the DeCSS illegal prime was created seemed the most interesting:  https://news.ycombinator.com/item?id=1045394This might be thought of as a human version of a covert channel:  https://en.wikipedia.org/wiki/Covert_channelE.g. publicizing the number and expiration date of Bill Gates' credit-card  is illegal but what if we wrote a text commentary about Shakespeare's Hamlet that when SHA-1 hashed, it gives you that same information?  Yes, it would be very computationally intensive to generate a plausible literary text but it could be done.  Or one embeds Bill Gates credit-card number as "transactions amounts" on Bitcoin blockchain.The theme is the same:  find a "legitimate" information channel to transmit illegitimate data.  This then allows the philosophical arguments about information:- How can commentary about Shakespeare be illegal? It's education!- How can you censor transactions on the bitcoin blockchain?  There are already 100,000+ copies of it on nodes around the globe!  And so on...