Add ByteUtils, more refactoring

Author: hckr

ByteUtils.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+
+namespace Padding_Oracle_Attack
+{
+    static class ByteUtils
+    {
+        public static List<byte[]> sliceBytesIntoBlocks(byte[] bytes, int blockSizeBytes = 16)
+        {
+            var blocks = new List<byte[]>();
+
+            for (var i = 0; i < bytes.Length; i += blockSizeBytes)
+            {
+                byte[] block = new byte[blockSizeBytes];
+                Array.Copy(bytes, i, block, 0, blockSizeBytes);
+                blocks.Add(block);
+            }
+
+            return blocks;
+        }
+
+        public static byte[] xor(byte[] bytes, byte[] other)
+        {
+            if (bytes.Length != other.Length)
+            {
+                throw new ArgumentException("Both arrays must have same length");
+            }
+
+            var result = new byte[bytes.Length];
+
+            for (int i = 0; i < bytes.Length; ++i)
+            {
+                result[i] = (byte)(bytes[i] ^ other[i]);
+            }
+
+            return result;
+        }
+
+        public static byte[] concat(byte[] first, byte[] second)
+        {
+            var result = new byte[first.Length + second.Length];
+
+            first.CopyTo(result, 0);
+            second.CopyTo(result, first.Length);
+
+            return result;
+        }
+    }
+}

Program.cs

@@ -1,44 +1,27 @@
 using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Security.Cryptography;
 
 namespace Padding_Oracle_Attack
 {
+    using static ByteUtils;
+
     class PaddingOracleAttack
     {
         private static RemoteServerMock server = new RemoteServerMock();
+
         public static void Main()
         {
             string hiddenMessage = "I'd just like to interject for a moment. What you’re referring to as Linux, is in fact, GNU/Linux, or as I’ve recently taken to calling it, GNU plus Linux.";
 
-            using (Aes aes = Aes.Create())
-            {
-                byte[] encrypted = server.Encrypt(hiddenMessage);
-                var blocks = sliceBytesIntoBlocks(encrypted);
-
-                Console.WriteLine("Plaintext:\n{0}", hiddenMessage);
-                Console.WriteLine("\nCiphertext:\n{0}", String.Join("\n", blocks.ConvertAll(block => Convert.ToBase64String(block))));
-                Console.WriteLine("\nAttack results:\nTODO");
-
-                encrypted[encrypted.Length - 1] = 22;
+            byte[] encrypted = server.Encrypt(hiddenMessage);
+            var blocks = sliceBytesIntoBlocks(encrypted);
 
-                Console.WriteLine("\nPadding is {0}", server.IsPaddingCorrect(encrypted) ? "correct" : "incorrect");
-            }
-        }
-
-        static List<byte[]> sliceBytesIntoBlocks(byte[] bytes, int blockSizeBytes = 16)
-        {
-            var blocks = new List<byte[]>();
+            Console.WriteLine("Plaintext:\n{0}", hiddenMessage);
+            Console.WriteLine("\nCiphertext:\n{0}", String.Join("\n", blocks.ConvertAll(block => Convert.ToBase64String(block))));
+            Console.WriteLine("\nAttack results:\nTODO");
 
-            for (var i = 0; i < bytes.Length; i += blockSizeBytes)
-            {
-                byte[] block = new byte[blockSizeBytes];
-                Array.Copy(bytes, i, block, 0, blockSizeBytes);
-                blocks.Add(block);
-            }
+            encrypted[encrypted.Length - 1] = 22;
 
-            return blocks;
+            Console.WriteLine("\nPadding is {0}", server.IsPaddingCorrect(encrypted) ? "correct" : "incorrect");
         }
     }
 }