From 57ceb5794bf99706c4a7e7ac1dc96ea1773c4798 Mon Sep 17 00:00:00 2001
From: Crsky <crskycode@hotmail.com>
Date: Sun, 28 Sep 2025 01:37:54 +0800
Subject: [PATCH] (ShiinaRio): Added Ushimitsu2Crypt

---
 ArcFormats/ShiinaRio/WarcEncryption.cs | 39 ++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/ArcFormats/ShiinaRio/WarcEncryption.cs b/ArcFormats/ShiinaRio/WarcEncryption.cs
index 0dee3078..f461a064 100644
--- a/ArcFormats/ShiinaRio/WarcEncryption.cs
+++ b/ArcFormats/ShiinaRio/WarcEncryption.cs
@@ -1316,4 +1316,43 @@ namespace GameRes.Formats.ShiinaRio
             }
         }
     }
+
+    [Serializable]
+    public class Ushimitsu2Crypt : IDecryptExtra
+    {
+        public void Decrypt (byte[] data, int index, uint length, uint flags)
+        {
+            byte[] key = new byte[]
+            {
+                0x4B, 0x4D, 0x36, 0x35, 0x33, 0x32, 0x20, 0x43,
+                0x50, 0x55, 0x20, 0x63, 0x6F, 0x72, 0x65, 0x20,
+                0x65, 0x6D, 0x75, 0x6C, 0x61, 0x74, 0x69, 0x6F,
+                0x6E, 0x20, 0x3A, 0x20, 0x43, 0x6F, 0x70, 0x79,
+                0x72, 0x69, 0x67, 0x68, 0x74, 0x28, 0x43, 0x29,
+                0x20, 0x32, 0x30, 0x30, 0x35, 0x2C, 0x36, 0x20,
+                0x59, 0x2E, 0x59, 0x61, 0x6D, 0x61, 0x64, 0x61,
+                0x2F, 0x53, 0x54, 0x55, 0x44, 0x49, 0x4F, 0x20,
+                0x82, 0xE6, 0x82, 0xB5, 0x82, 0xAD, 0x82, 0xF1
+            };
+
+            if (length >= 0x200)
+            {
+                if ((flags & 0x202) == 0x202)
+                {
+                    for (int i = 0; i < ((length & 0x7E) | 1); i++)
+                    {
+                        data[index+i] ^= key[i % 0x40];
+                    }
+                    var value = MemoryMarshal.Read<uint> (data.AsSpan (index+0x100));
+                    value ^= length;
+                    MemoryMarshal.Write<uint> (data.AsSpan (index+0x100), ref value);
+                }
+            }
+        }
+
+        public void Encrypt (byte[] data, int index, uint length, uint flags)
+        {
+            throw new NotImplementedException ();
+        }
+    }
 }