From 85c015f7ff9637d51f211334ed0d69b88aecf2b0 Mon Sep 17 00:00:00 2001
From: Christian Engelhardt <cengelha.appdevl@outlook.com>
Date: Sun, 21 Jul 2024 22:52:11 +0200
Subject: [PATCH] fix(Steam): meta file enrcyption

---
 libNOM.io/PlatformSteam.cs | 14 +++++++-------
 libNOM.io/libNOM.io.csproj |  2 +-
 libNOM.test/Steam.cs       | 22 ++++++++++++++++++++++
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/libNOM.io/PlatformSteam.cs b/libNOM.io/PlatformSteam.cs
index 51d35b7..ffe57b2 100644
--- a/libNOM.io/PlatformSteam.cs
+++ b/libNOM.io/PlatformSteam.cs
@@ -220,15 +220,15 @@ 91. EMPTY                ( 20) // META_FORMAT_4
             }
             if (container.IsSave)
             {
-            // Extended metadata since Waypoint 4.00.
-            UpdateContainerWithWaypointMetaInformation(container, disk);
+                // Extended metadata since Waypoint 4.00.
+                UpdateContainerWithWaypointMetaInformation(container, disk);
 
                 // Extended metadata including a new META_FORMAT since Worlds 5.00.
                 UpdateContainerWithWorldsMetaInformation(container, disk, decompressed);
 
-            // GameVersion with BaseVersion only is not 100% accurate but good enough to calculate SaveVersion.
-            container.SaveVersion = Meta.SaveVersion.Calculate(container, Meta.GameVersion.Get(container.Extra.BaseVersion));
-        }
+                // GameVersion with BaseVersion only is not 100% accurate but good enough to calculate SaveVersion.
+                container.SaveVersion = Meta.SaveVersion.Calculate(container, Meta.GameVersion.Get(container.Extra.BaseVersion));
+            }
         }
 
         // Size is save to write always.
@@ -299,7 +299,7 @@ protected override Span<uint> DecryptMeta(Container container, Span<byte> meta)
 
                 uint i1 = (current >> 3) ^ (result[valueIndex] << 4);
                 uint i2 = (current * 4) ^ (result[valueIndex] >> 5);
-                uint i3 = (result[valueIndex] ^ key[keyIndex]);
+                uint i3 = (result[valueIndex] ^ key[keyIndex]); // [(0 & 3) ^ keyIndex] as in j3 to be precise (0 would be the last executed index) but (0 & 3) is always zero and therefore does not matter
                 uint i4 = (current ^ hash);
                 result[0] -= (i1 + i2) ^ (i3 + i4);
 
@@ -441,7 +441,7 @@ protected override ReadOnlySpan<byte> EncryptMeta(Container container, ReadOnlyS
 
             uint i1 = (value[0] >> 3) ^ (current << 4);
             uint i2 = (value[0] * 4) ^ (current >> 5);
-            uint i3 = (current ^ key[keyIndex ^ 1]);
+            uint i3 = (current ^ key[(lastIndex & 3) ^ keyIndex]);
             uint i4 = (value[0] ^ hash);
             value[lastIndex] += (i1 + i2) ^ (i3 + i4);
             current = value[lastIndex];
diff --git a/libNOM.io/libNOM.io.csproj b/libNOM.io/libNOM.io.csproj
index edc6e28..6ad6061 100644
--- a/libNOM.io/libNOM.io.csproj
+++ b/libNOM.io/libNOM.io.csproj
@@ -58,7 +58,7 @@
 
 	<!-- Package -->
 	<PropertyGroup Label="General">
-		<Version>0.10.0-beta.8</Version>
+		<Version>0.10.0-beta.9</Version>
 		<Authors>cengelha</Authors>
 		<Description>Provides reading and writing save files from the game No Man's Sky for all possible platforms as well as related actions.</Description>
 		<Copyright>Copyright (c) Christian Engelhardt 2021</Copyright>
diff --git a/libNOM.test/Steam.cs b/libNOM.test/Steam.cs
index 244367a..5d7df29 100644
--- a/libNOM.test/Steam.cs
+++ b/libNOM.test/Steam.cs
@@ -147,6 +147,28 @@ private static void AssertCommonMeta(IContainer container, uint[] metaA, uint[]
                 Assert.IsTrue(metaA.Skip(20).SequenceEqual(metaB.Skip(20)));
             }
         }
+        else if (metaA.Length == META_LENGTH_TOTAL_WORLDS)
+        {
+            AssertAllAreEqual(META_FORMAT_4, metaA[1], metaB[1]);
+
+            if (container.IsAccount)
+            {
+                AssertAllNotZero(metaA.Skip(2).Take(4), metaB.Skip(2).Take(4));
+                AssertAllNotZero(metaA.Skip(6).Take(8), metaB.Skip(6).Take(8));
+                AssertAllZero(metaA.Skip(14), metaB.Skip(14));
+            }
+            else
+            {
+                AssertAllZero(metaA.Skip(2).Take(12), metaB.Skip(2).Take(12));
+                AssertAllNotZero(metaA.Skip(14).Take(2), metaB.Skip(14).Take(2));
+                AssertAllZero(metaA[16], metaB[16]);
+                Assert.IsTrue(metaA.Skip(20).Take(69).SequenceEqual(metaB.Skip(20).Take(69)));
+                AssertAllNotZero(metaA[89], metaB[89]);
+                AssertAllAreEqual(META_FORMAT_4, metaA[90], metaB[90]);
+                AssertAllZero(metaA.Skip(91), metaB.Skip(91));
+
+            }
+        }
         else
             throw new AssertFailedException();
     }