diff --git a/ArcFormats/Aoi/ArcBOX.cs b/ArcFormats/Aoi/ArcBOX.cs
index d99babf3..be882cbb 100644
--- a/ArcFormats/Aoi/ArcBOX.cs
+++ b/ArcFormats/Aoi/ArcBOX.cs
@@ -140,7 +140,7 @@ namespace GameRes.Formats.Aoi
             var barc = arc as BoxArchive;
             if (null == barc)
                 return input;
-            return new CryptoStream (input, new XorTransform (barc.Key), CryptoStreamMode.Read);
+            return new XoredStream (input, barc.Key);
         }
     }
 
diff --git a/ArcFormats/ArcIKS.cs b/ArcFormats/ArcIKS.cs
index d63b200c..d5169f34 100644
--- a/ArcFormats/ArcIKS.cs
+++ b/ArcFormats/ArcIKS.cs
@@ -80,7 +80,7 @@ namespace GameRes.Formats.X
         {
             byte key = KnownKeys.First().Value;
             var input = arc.File.CreateStream (entry.Offset, entry.Size);
-            return new CryptoStream (input, new XorTransform (key), CryptoStreamMode.Read);
+            return new XoredStream (input, key);
         }
     }
 }
diff --git a/ArcFormats/KScript/ImageKGP.cs b/ArcFormats/KScript/ImageKGP.cs
index 0580c968..8c1756f8 100644
--- a/ArcFormats/KScript/ImageKGP.cs
+++ b/ArcFormats/KScript/ImageKGP.cs
@@ -58,7 +58,7 @@ namespace GameRes.Formats.KScript
                 y = header.ToInt32 (0x18);
             }
             using (var input = new StreamRegion (stream.AsStream, data_offset, true))
-            using (var crypto = new CryptoStream (input, new XorTransform (key), CryptoStreamMode.Read))
+            using (var crypto = new XoredStream (input, key))
             using (var png = new BinaryStream (crypto, stream.Name))
             {
                 var info = Png.ReadMetaData (png);
@@ -82,7 +82,7 @@ namespace GameRes.Formats.KScript
         {
             var meta = (KgpMetaData)info;
             using (var input = new StreamRegion (stream.AsStream, meta.DataOffset, true))
-            using (var crypto = new CryptoStream (input, new XorTransform (meta.Key), CryptoStreamMode.Read))
+            using (var crypto = new XoredStream (input, meta.Key))
             using (var png = new BinaryStream (crypto, stream.Name))
                 return Png.Read (png, info);
         }
diff --git a/ArcFormats/Slg/ArcSZS.cs b/ArcFormats/Slg/ArcSZS.cs
index 24970d02..1eeacd98 100644
--- a/ArcFormats/Slg/ArcSZS.cs
+++ b/ArcFormats/Slg/ArcSZS.cs
@@ -70,7 +70,7 @@ namespace GameRes.Formats.Slg
         public override Stream OpenEntry (ArcFile arc, Entry entry)
         {
             var input = arc.File.CreateStream (entry.Offset, entry.Size);
-            return new CryptoStream (input, new XorTransform (0x90), CryptoStreamMode.Read);
+            return new XoredStream (input, 0x90);
         }
     }
 }