[lotharbot]

Is there any reason you linked to a third-party site instead of xkcd itself?

http://xkcd.com/538/ (easily googled -- xkcd crypto, first hit.)

[chrisjsmith]

Oh pedant, I thoroughly apologise for my ignorance. May my vegetables all die, my breath smell for eternity and my armpits flood with hair and engulf the earth.

[cfaubell]

It's not pedantry. Linking directly to the content's author makes sure that he is properly credited and gets the exposure.