illegal number
lorecryptographyprivacyops culture
A number whose mere possession or publication is claimed to be unlawful, the reductio ad absurdum of information control.
When DVD encryption was broken, Phil Carmody found a prime number that literally is the DeCSS decryption code, executable when unpacked, making a prime arguably illegal to publish. In May 2007 the AACS consortium sent takedowns for the 16-byte HD DVD processing key beginning 09 F9, and Digg's users answered by posting it in songs, images, and T-shirts until the site's operators surrendered to the flood. Every such episode restates the same theorem: bits are numbers, numbers are speech, and secrecy by legal threat does not survive contact with the Streisand effect.
An illegal number is an integer that is unlawful to possess or distribute in some jurisdiction, because its binary representation is a piece of prohibited data. The concept arose during the DeCSS litigation, when the DVD decryption key was expressed as a number, printed on shirts, and set to music specifically to demonstrate the absurdity.
The point being made is genuine and holds up. Any data is a number, so a prohibition on distributing particular data is a prohibition on distributing particular integers, and the boundary between an act and a fact becomes very hard to draw. The same reasoning underlies the argument that source code is speech, which succeeded in United States courts during the crypto wars.
The corollary is uncomfortable in both directions. Taken literally it implies that almost any restriction on information is incoherent, which proves too much, since child abuse material is also a number and nobody accepts that argument there. What the illegal number demonstrates is that laws written about physical distribution translate badly to information, and that the translation requires actual reasoning about harm rather than a mechanical extension of property concepts.
Also known as: 09 F9, illegal prime