An illegal prime is a prime number that represents information whose possession or distribution is forbidden in some legal jurisdiction. One of the first illegal primes was found in 2001. When interpreted in a particular way, it describes a computer program that bypasses the digital rights management scheme used on DVDs. Distribution of such a program in the United States is illegal under the Digital Millennium Copyright Act. An illegal prime is a kind of illegal number.
“This is a good short lesson in public key cryptography. We also learn why a particular prime number that starts with 85650789657397829 and has 1402 more digits is an illegal number. If you have a DVD player, you are in possession of the number.”
This would seem like a case of math defeating copyright law but….