Port (raw) password decryption code to C#.

src/Syroot.Worms/OnlineWorms/LaunchConfig.cs

@@ -18,6 +18,7 @@ namespace Syroot.Worms.OnlineWorms
         private static readonly char[] _invalidUserNameChars = { '=', '&', ' ' };
 
         private string _userName;
+        private string _passwordString;
 
         // ---- CONSTRUCTORS & DESTRUCTOR ------------------------------------------------------------------------------
 
@@ -51,11 +52,6 @@ namespace Syroot.Worms.OnlineWorms
             }
         }
 
-        /// <summary>
-        /// Gets or sets the initially entered password. This value is encrypted before being stored in the config.
-        /// </summary>
-        public string Password { get; set; }
-
         // ---- METHODS (PUBLIC) ---------------------------------------------------------------------------------------
 
         /// <summary>
@@ -72,9 +68,11 @@ namespace Syroot.Worms.OnlineWorms
             {
                 stream.Write("Online Worms Config File");
 
+                if (_passwordString != null)
+                {
                     stream.Position = 36;
-                // TODO: Encrypt password and pass appropriate key as ";encryptedData;key".
+                    stream.Write(_passwordString);
-                stream.Write(";Unknown;0");
+                }
 
                 stream.Position = 66;
                 stream.Write("UID=", StringCoding.Raw);
@@ -87,5 +85,98 @@ namespace Syroot.Worms.OnlineWorms
             }
             return mappedFile;
         }
+
+        /// <summary>
+        /// Removes any previously set password in the configuration.
+        /// </summary>
+        public void ClearPassword()
+        {
+            _passwordString = null;
+        }
+
+        /// <summary>
+        /// Decrypts the password stored in the configuration as previously set through
+        /// <see cref="SetPassword(String, Int32)"/>.
+        /// </summary>
+        public string GetPassword()
+        {
+            // TODO: Decrypt password:
+            return _passwordString;
+        }
+
+        /// <summary>
+        /// Encrypts the given <paramref name="password"/> with the provided initial encryption <paramref name="key"/>
+        /// and stores the result in the launch config.
+        /// </summary>
+        /// <param name="password">The password to store encrypted.</param>
+        /// <param name="key">The key to encrypt with.</param>
+        public void SetPassword(string password, int key)
+        {
+            // TODO: Encrypt password.
+            _passwordString = $";{password};{key}";
+        }
+
+        // ---- METHODS (PRIVATE) --------------------------------------------------------------------------------------
+
+        public string DecryptPassword(string data, int key)
+        {
+            byte[] decodeBuffer = new byte[64];
+            int decodeIdx = 0;
+            int idx = 0;
+            do
+            {
+                int subIdx = 0;
+                uint curValue = 0;
+                string dataRemain = data.Substring(idx);
+                do
+                {
+                    uint baseValue = 1;
+                    if (subIdx > 0)
+                    {
+                        int subIdxCounter = subIdx;
+                        do
+                        {
+                            baseValue *= 36;
+                            subIdxCounter--;
+                        } while (subIdxCounter != 0);
+                    }
+                    char c = dataRemain[subIdx];
+                    uint factor = (uint)(c < '0' || c > '9' ? c - '7' : c - '0');
+                    curValue += baseValue * factor;
+                    ++subIdx;
+                } while (subIdx < 7);
+                idx += 7;
+                int value = DecryptValue(curValue, 0) - key;
+                Buffer.BlockCopy(BitConverter.GetBytes(value), 0, decodeBuffer, decodeIdx++, sizeof(int));
+            } while (idx < data.Length);
+            return Encoding.ASCII.GetString(decodeBuffer);
+        }
+
+        public int DecryptValue(uint value, int shiftArrayIndex)
+        {
+            int[][] shifts = new int[][]
+            {
+                new[] { 18, 29, 7, 25, 15, 31, 22, 27, 9, 26, 3, 13, 19, 14, 20, 11, 5, 2, 23, 16, 10, 24, 28, 17, 6, 30, 0, 21, 12, 8, 4, 1 },
+                new[] { 26, 31, 17, 10, 30, 16, 24, 2, 29, 8, 20, 15, 28, 11, 13, 4, 19, 23, 0, 12, 14, 27, 6, 18, 21, 3, 9, 22, 7, 1, 25, 5 }
+            };
+
+            int result = 0;
+            if (value != 0)
+            {
+                int idx = 0;
+                do
+                {
+                    uint highBits = (uint)(value - (value & ~1));
+                    value >>= 1; // / 2
+                    if (highBits != 0)
+                    {
+                        int shift = shifts[shiftArrayIndex][idx];
+                        result += (int)(highBits << shift);
+                    }
+                    idx++;
+                } while (value != 0);
+            }
+            return result;
+        }
     }
 }