#!/usr/bin/ruby # # CODEGATE2011 CTF Pre-qual Crypto100 Writeup # # how to: # $ ruby crypt100-writeup.rb # incryptographyasubstitutioncipherisamethodofencryptionbywhichunitsof # plaintextarereplacedwithciphertextaccordingtoaregularsystemtheun

gistfile1.txt

#!/usr/bin/ruby
#
# CODEGATE2011 CTF Pre-qual Crypto100 Writeup
#
# how to:
#  $ ruby crypt100-writeup.rb 
#   incryptographyasubstitutioncipherisamethodofencryptionbywhichunitsof
#   plaintextarereplacedwithciphertextaccordingtoaregularsystemtheunits
#   maybesingleletterspairsofletterstripletsoflettersmixturesoftheabovethis
#   ciphertextisencryptedbytelephonekeypadsowecallthiskeypadcipher
#  
#  -> keypad cipher
#
ary = [
 444,  66, 222, 777, 999,   7,   8, 666,   4, 777,
   2,   7,  44, 999,   2,7777,  88,  22,7777,   8,
 444,   8,  88,   8, 444, 666,  66, 222, 444,   7,
  44,  33, 777, 444,7777,   2,   6,  33,   8,  44,
 666,   3, 666, 333,  33,  66, 222, 777, 999,   7,
   8, 444, 666,  66,  22, 999,   9,  44, 444, 222,
  44,  88,  66, 444,   8,7777, 666, 333,   7, 555,
   2, 444,  66,   8,  33,  99,   8,   2, 777,  33,
 777,  33,   7, 555,   2, 222,  33,   3,   9, 444,
   8,  44, 222, 444,   7,  44,  33, 777,   8,  33,
  99,   8,   2, 222, 222, 666, 777,   3, 444,  66,
   4,   8, 666,   2, 777,  33,   4,  88, 555,   2,                                                            
 777,7777, 999,7777,   8,  33,   6,   8,  44,  33,
  88,  66, 444,   8,7777,   6,   2, 999,  22,  33,                                                            
7777, 444,  66,   4, 555,  33, 555,  33,   8,   8,
  33, 777,7777,   7,   2, 444, 777,7777, 666, 333,                                                            
 555,  33,   8,   8,  33, 777,7777,   8, 777, 444,
   7, 555,  33,   8,7777, 666, 333, 555,  33,   8,                                                            
   8,  33, 777,7777,   6, 444,  99,   8,  88, 777,
  33,7777, 666, 333,   8,  44,  33,   2,  22, 666,                                                            
 888,  33,   8,  44, 444,7777, 222, 444,   7,  44,
  33, 777,   8,  33,  99,   8, 444,7777,  33,  66,                                                            
 222, 777, 999,   7,   8,  33,   3,  22, 999,   8,
  33, 555,  33,   7,  44, 666,  66,  33,  55,  33,                                                            
 999,   7,   2,   3,7777, 666,   9,  33, 222,   2,
 555, 555,   8,  44, 444,7777,  55,  33, 999,   7,                                                            
   2,   3, 222, 444,   7,  44,  33, 777
]                                                                                                             

table = {                                                                                                     
     2 => "a",
    22 => "b",                                                                                                
   222 => "c",
     3 => "d",                                                                                                
    33 => "e",
   333 => "f",                                                                                                
     4 => "g",
    44 => "h",                                                                                                
   444 => "i",
     5 => "j",                                                                                                
    55 => "k",
   555 => "l",                                                                                                
     6 => "m",
    66 => "n",                                                                                                
   666 => "o",
     7 => "p",                                                                                                
    77 => "q",
   777 => "r",                                                                                                
  7777 => "s",
     8 => "t",
    88 => "u",
   888 => "v",
     9 => "w",
    99 => "x",
   999 => "y",
  9999 => "z"
}

ans = ary.map {|n| table[n]}

ans.each_with_index {|c, i|
  print c
}
puts

Thank you, I was looking for some sort of cipher list and this was very helpful .