Add support for DXArchive8 encryption.

ArcFormats/DxLib/DxKey.cs

@@ -26,6 +26,7 @@
 using System;
 using System.Linq;
 using System.Security.Cryptography;
+using System.Xml.Linq;
 using GameRes.Utility;
 
 namespace GameRes.Formats.DxLib
@@ -153,4 +154,57 @@ namespace GameRes.Formats.DxLib
             throw new NotSupportedException ("SHA-256 key cannot be restored.");
         }
     }
+
+    [Serializable]
+    public class DxKey8 : DxKey
+    {
+        public DxKey8(string password) : base(password ?? "DXARC")
+        {
+        }
+
+        public override byte[] GetEntryKey(string name)
+        {
+            var password = this.Password;
+            var path = name.Split('\\', '/');
+            password += string.Join("", path.Reverse().Select(n => n.ToUpperInvariant()));
+            return CreateKey(password);
+        }
+
+        protected override byte[] CreateKey(string keyword)
+        {
+            //from DxArchive.cpp
+            //first check if the keyword is too short
+            if (keyword.Length < 4)
+            {
+                keyword += "DXARC";
+            }
+            string oddString, evenString;
+            byte[] key = new byte[7];
+            oddString = string.Concat(keyword.Where((c, i) => i % 2 == 0));
+            evenString = string.Concat(keyword.Where((c, i) => (i+1) % 2 == 0));
+            UInt32 crc_0, crc_1;
+            crc_0 = Crc32.Compute(Encodings.ASCII.GetBytes(oddString), 0, oddString.Length);
+            crc_1 = Crc32.Compute(Encodings.ASCII.GetBytes(evenString), 0, evenString.Length);
+            byte[] crc_0_Bytes = BitConverter.GetBytes(crc_0),crc_1_Bytes=BitConverter.GetBytes(crc_1);
+            key[0] = crc_0_Bytes[0];
+            key[1] = crc_0_Bytes[1];
+            key[2] = crc_0_Bytes[2];
+            key[3] = crc_0_Bytes[3];
+            key[4] = crc_1_Bytes[0];
+            key[5] = crc_1_Bytes[1];
+            key[6] = crc_1_Bytes[2];
+            return key;
+            /*
+            using (var sha = SHA256.Create())
+            {
+                var bytes = Encodings.cp932.GetBytes(keyword);
+                return sha.ComputeHash(bytes);
+            } */
+        }
+
+        protected override string RestoreKey(byte[] key)
+        {
+            throw new NotSupportedException("CRC key cannot be restored.");
+        }
+    }
 }

GameRes/ArcView.cs

@@ -33,7 +33,8 @@ namespace GameRes
 {
     public static class Encodings
     {
-        public static readonly Encoding cp932 = Encoding.GetEncoding (932);
+        public static readonly Encoding cp932 = Encoding.GetEncoding(932);
+        public static readonly Encoding ASCII = Encoding.GetEncoding(32765);
 
         public static Encoding WithFatalFallback (this Encoding enc)
         {