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### Author Topic: p eq b & b not l => p not l. proof is left as an exercise  (Read 3755 times)

#### gjehle

• Member
• Joined in 2006
• Posts: 286
• lonesome linux warrior
##### p eq b & b not l => p not l. proof is left as an exercise
« on: April 15, 2006, 06:12 AM »

"An illegal prime is a prime number which contains information forbidden by law to possess or distribute.

The first illegal prime to be announced, when interpreted a particular way, describes a computer program which bypasses copyright protection schemes on some DVDs. Because that program has been found illegal by courts in the United States of America, this has produced debate about whether the number itself could be considered illegal." - Wikipedia

http://en.wikipedia....g/wiki/Illegal_prime

#### mouser

• First Author
• Joined in 2005
• Posts: 40,912
##### Re: p eq b & b not l => p not l. proof is left as an exercise
« Reply #1 on: April 15, 2006, 06:14 AM »
sooo cool.
the mind of man at it's best.

#### Eóin

• Charter Member
• Joined in 2006
• Posts: 1,401
##### Re: p eq b & b not l => p not l. proof is left as an exercise
« Reply #2 on: April 15, 2006, 02:10 PM »
More DeCSS fun can be found at Gallery of CSS Descramblers .

#### jgpaiva

• Global Moderator
• Joined in 2006
• Posts: 4,727
##### Re: p eq b & b not l => p not l. proof is left as an exercise
« Reply #3 on: April 16, 2006, 05:45 PM »
I see what you mean, and it actually is a good point. I learned how to do that at school, and it's quite unbelievable how it works.
If you are given the language you're working with, you can translate a whole program into just one number, and translate it back.
I was told it is a method also used with cryptography. I did it with a 10 instruction and 4 keyword program, and it was quite easy. But i guess doing it with a whole C program, would make it quite hard. (although i guess the program could be automated)
Still, making a number copywrighted looks like a bit dumb to me.