That way, if you ever inadvertently share a folder full of copyright material on a P2P network and the Net cops (MPAA and their ilk) show up with a seizure order for your box, all they'll get is garbage. Therefore, they'll be incapable of PROVING you ever even had copyright material.
I can guarantee it will stop them in their tracks.
Below are some links for public domain free software that will encrypt your hard drive and make it impenetrable for all intents and purposes. They won't be able to afford to even try to discover what is there because it would require all of the computing power currently available in all of the computers on Earth till the end of time to decrypt your hard drive by brute force and you cannot be compelled to disclose your passphrase because of the 5th Amendment.
Barring any new technology (like quantum computing which could theoretically provide all of the possible solutions simultaneously which would still leave the difficulty of looking at billions of solutions), your hard drive will be eternally secure.
And, before some popinjay comes along and claims that some super-secret government organization has a super computer that CAN break encrypted files, I submit that if it did exist, it wouldn't be super-secret if it were widely known. I'll only believe such when the US Government no longer classifies encryption as a weapon.
If anyone claims such, they just do not understand the math or the process behind encryption technologies in use today. Some old technologies have been breached because of the small set of possible keys (DES 56) or a flaw in the math.
Use encryption that uses vetted algorithms and public domain code. Public domain code means that there can be no hidden "backdoors" or computational flaws to make it vulnerable. Vetted algorithms have been tested by the community of peers in academia to ensure that the math is sound.
Check these out TODAY!
http://www.truecrypt.org/
and free security resources of all kinds including encryption
http://www.thefreecountry.com/
and . . .
http://www.freebyte.com/security/
http://www.freeotfe.org/
et cetera.
Get an education about computer security and the law.
I like to know the rules and beat them over the head with them!
PS: I neither participate in nor encourage any illegal activity. I DO NOT own nor share illegally obtained copyrighted materials of any kind. I believe that people should be paid for their work whether it is digging ditches or providing entertainment if they choose not to put their work into the public domain. Everybody has to eat.
PSS: I claim no copyright to this material.
