refactored, cleaned up and wrote README

README

@@ -0,0 +1,48 @@
+== Ruby-DES
+
+Ruby-DES is a full Ruby implementation of the Data Encryption Standard.  The purpose of this 
+project was to allow Ruby programmers interested in cryptography a glimpse of how a robust 
+cryptographic algorithm functions in a language they understand.
+
+NOTE: DES is deprecated, and as such, you should not use this implementation in any project you 
+plan on developing.  I highly recommend the AES, TwoFish or Serpent algorithms through the OpenSSL 
+library instead.
+
+== Running Ruby-DES
+
+Using RubyDES is pretty easy.  First, construct a new data and key block.
+
+  data = RubyDES::Block.new('hushhush')
+  key  = RubyDES::Block.new('password')
+
+Then, build a new <tt>RubyDES::Ctx</tt> object and supply the bit arrays for both the data and key 
+block.
+
+  des = RubyDES::Ctx.new(data.bit_array, key.bit_array)
+
+Finally, let it rip.
+
+  encrypted_data_bit_array = des.run(:encrypt)
+
+You will then be returned a DES encrypted bit array that is completely secure against eavesdropping 
+(if it were still 1997).
+
+To decrypt an encrypted array if bits, just build a new <tt>RubyDES::Ctx</tt> object in similar 
+fashion as before.
+
+  un_des = RubyDES::Ctx.new(encrypted_data_bit_array, key.bit_array)
+
+And run the DES with the key schedule reversed.
+
+  un_encrypted_data_bit_array = un_des.run(:decrypt)
+
+You can then check to see if it all worked.
+
+  data.bit_array.eql?(un_encrypted_data_bit_array)
+
+Enjoy!
+
+== Feedback
+
+If you have any questions, comments or just want to talk shop about crypto, feel free to reach me 
+through my website at http://www.robertsosinski.com

lib/ruby-des.rb

@@ -25,19 +25,23 @@ module RubyDES
         0x21, 0x01, 0x29, 0x09, 0x31, 0x11, 0x39, 0x19]
 
   class Ctx
-    attr_reader :block, :key
+    attr_reader :data, :key
 
-    def initialize(block, key)
-      @block = block
-      @key   = key
+    def initialize(data, key)
+      unless data.is_a?(Array) and key.is_a?(Array) and data.size.eql?(64) and key.size.eql?(64)
+        raise "RubyDES::InvalidBlockFormat: data and key attributes must be passed bit arrays that are 64 bits in size"
+      end
+
+      @data = data
+      @key  = key
     end
 
     def run(mode)
-      l = [] # l[0] is the IP_1_L permutation of the block, l[1..16] are the results of each round of encryption.
-      r = [] # r[0] is the IP_1_R permutation of the block, r[1..16] are the results of each round of encryption.
+      l = [] # l[0] is the IP_1_L permutation of the data block, l[1..16] are the results of each round of encryption.
+      r = [] # r[0] is the IP_1_R permutation of the data block, r[1..16] are the results of each round of encryption.
 
-      l << IP_L.collect{|p| block[p - 1]}
-      r << IP_R.collect{|p| block[p - 1]}
+      l << IP_L.collect{|p| data[p - 1]}
+      r << IP_R.collect{|p| data[p - 1]}
 
       case mode
       when :encrypt
@@ -54,4 +58,15 @@ def run(mode)
       return FP.collect{|p| (r.last + l.last)[p - 1]}
     end
   end
+
+  class Block
+    attr_reader :string, :bit_array
+
+    def initialize(string)
+      raise "RubyDES::InvalidStringSize: input string must contain (8) characters" unless string.length.eql?(8)
+
+      @string    = string
+      @bit_array = string.unpack('B*').join.split('').collect{|b| b.to_i}
+    end
+  end
 end

lib/ruby-des/feistel.rb

@@ -64,7 +64,7 @@ def self.run(r, k)
     m = [] # m[0..7] is the row of the value when performing a s-box lookup.
     n = [] # n[0..7] is the column of the value when performing a s-box lookup.
 
-    e = E.collect{|p| r[p - 1]} # Expand r (right half block) using E.
+    e = E.collect{|p| r[p - 1]} # Expand r (right half data block) using E.
 
     e_xor_k = XOR.run(e, k) # X-or e (expanded r) with k (the sub key).