; eval ▁ ▁Fast : ▁#!/ usr / bin / perl ▁- w ▁# ▁ 5 3 1 - byte ▁q rp ff - fast , ▁Keith ▁Win stein ▁and ▁Marc ▁Hor ow itz ▁< s ip b - ia p - d vd @ mit . edu > ▁# ▁M PE G ▁ 2 ▁PS ▁V OB ▁file ▁on ▁std in ▁-> ▁desc ram bled ▁output ▁on ▁stdout ▁# ▁arguments : ▁title ▁key ▁bytes ▁in ▁least ▁to ▁most - sign ific ant ▁order ▁ ▁$_ =' while ( read + ST D IN ,$ _, 2 0 4 8 ){ $ a = 2 9 ; $ b = 7 3 ; $ c = 1 4 2 ; $ t = 2 5 5 ; @ t = map {$ _ % 1 6 or $ t ^ =$ c ^ =( ▁$ m =( 1 1 , 1 0 , 1 1 6 , 1 0 0 , 1 1 , 1 2 2 , 2 0 , 1 0 0 ) [$ _ / 1 6 % 8 ]) & 1 1 0 ; $ t ^ =( 7 2 , @ z =( 6 4 , 7 2 ,$ a ^ = 1 2 * ($_ % 1 6 ▁- 2 ? 0 :$ m & 1 7 )), $ b ^ =$ _ % 6 4 ? 1 2 : 0 , @ z ) [$ _ % 8 ] }( 1 6 .. 2 7 1