From 329589122aad3b8514ccea388cf4be6163d37f63 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C5=82awomir=20=C5=9Apiewak?=
 <sosw.slawomir.spiewak@gmail.com>
Date: Sun, 18 Aug 2024 10:46:41 +0200
Subject: [PATCH] Fix cases where files with non-ascii names would fail to
 decrypt.

---
 ArcFormats/DxLib/ArcDX8.cs |  5 +----
 ArcFormats/DxLib/DxKey.cs  | 37 ++++++++++++++++++++++++++++++-------
 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/ArcFormats/DxLib/ArcDX8.cs b/ArcFormats/DxLib/ArcDX8.cs
index 45b46528..8daf5bfd 100644
--- a/ArcFormats/DxLib/ArcDX8.cs
+++ b/ArcFormats/DxLib/ArcDX8.cs
@@ -150,7 +150,7 @@ namespace GameRes.Formats.DxLib
             if (isencrypted)
             {
                 var keyStr = Query<DXAOpts>(arcStrings.ZIPEncryptedNotice).Keyword;
-                key = new DxKey8(keyStr);
+                key = new DxKey8(keyStr,dx.CodePage);
 
                 
             }
@@ -191,9 +191,6 @@ namespace GameRes.Formats.DxLib
             long dec_offset =  dx_ent.UnpackedSize; 
             var key = dx_arc.Encryption.GetEntryKey(dx_ent.Name);
             input = new EncryptedStream(input, dec_offset, key);
-            if (!dx_ent.HuffmanCompressed && !dx_ent.IsPacked)
-                return input;
-            //we ruled out the case in which neither compression is applied. We still have 3 cases to go.
 
             byte[] tmpBuffer = new byte[dx_ent.Size]; 
             input.Read(tmpBuffer, 0, tmpBuffer.Length);
diff --git a/ArcFormats/DxLib/DxKey.cs b/ArcFormats/DxLib/DxKey.cs
index 6fdcccff..5e5ba6b9 100644
--- a/ArcFormats/DxLib/DxKey.cs
+++ b/ArcFormats/DxLib/DxKey.cs
@@ -159,8 +159,10 @@ namespace GameRes.Formats.DxLib
     [Serializable]
     public class DxKey8 : DxKey
     {
-        public DxKey8(string password) : base(password ?? "DXARC")
+        private int codepage;
+        public DxKey8(string password,int codepage) : base(password ?? "DXARC")
         {
+            this.codepage = codepage;
         }
 
         public override byte[] GetEntryKey(string name)
@@ -179,13 +181,26 @@ namespace GameRes.Formats.DxLib
             {
                 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));
+            //first split string to bytes. Use original encoding as basis. Otherwise we would fail to decrypt that.
+            Encoding defEncoding = Encoding.UTF8;
+            Encoding tgtEncoding = Encoding.GetEncoding(codepage);
+            byte[] defBytes = defEncoding.GetBytes(keyword);
+            byte[] tgtBytes = Encoding.Convert(defEncoding, tgtEncoding, defBytes);
+            byte[] oddBuffer = new byte[tgtBytes.Length]; int oddCounter = 0;
+            byte[] evenBuffer = new byte[tgtBytes.Length]; int evenCounter = 0;
+            for (int i=0; i<tgtBytes.Length;i+=2,oddCounter++)
+            {
+                oddBuffer[oddCounter] = tgtBytes[i];
+            }
+            for (int i = 1; i < tgtBytes.Length; i += 2, evenCounter++)
+            {
+                evenBuffer[evenCounter] = tgtBytes[i];
+            }
             UInt32 crc_0, crc_1;
-            crc_0 = Crc32.Compute(Encoding.ASCII.GetBytes(oddString), 0, oddString.Length);
-            crc_1 = Crc32.Compute(Encoding.ASCII.GetBytes(evenString), 0, evenString.Length);
+            crc_0 = Crc32.Compute(oddBuffer, 0, oddCounter);
+            crc_1 = Crc32.Compute(evenBuffer, 0, evenCounter);
+
+            byte[] key = new byte[7];
             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];
@@ -195,6 +210,14 @@ namespace GameRes.Formats.DxLib
             key[5] = crc_1_Bytes[1];
             key[6] = crc_1_Bytes[2];
             return key;
+
+            /*
+            string oddString, evenString;
+            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(Encoding.ASCII.GetBytes(oddString), 0, oddString.Length);
+            crc_1 = Crc32.Compute(Encoding.ASCII.GetBytes(evenString), 0, evenString.Length); */
             /*
             using (var sha = SHA256.Create())
             {