i think its extremely abbreviated and slightly in slang, as for the numbers and dash's they must of been added later in his life once his intelligence increased.
how many children can do even slightly complex encrytion/decrytion in their heads? not very many i would say...
http://www.fbi.gov/news/stories/2011/march/cryptanalysis_032911
chmod ---x--x--x,, i'm illiterate!