Add symbolObfusSettings.nameRandomSeed to randomise generated symbol names

Upstream assigns obfuscated names from a monotonic base-52 counter, so two
builds of the same source produce an identical mapping and a build with a
small source change keeps almost every previous name. An attacker who
reverses build N therefore carries that work forward to build N+1.

nameRandomSeed = 0 keeps the original counter, so this is opt-in and the
default behaviour is unchanged.

Editor/ObfusPasses/SymbolObfus/NameMakers/NameMakerFactory.cs

@@ -1,4 +1,4 @@
-// Copyright 2025 Code Philosophy
+// Copyright 2025 Code Philosophy
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -30,6 +30,11 @@ namespace Obfuz.ObfusPasses.SymbolObfus.NameMakers
         }
 
         public static INameMaker CreateNameMakerBaseASCIICharSet(string namePrefix)
+        {
+            return CreateNameMakerBaseASCIICharSet(namePrefix, 0);
+        }
+
+        public static INameMaker CreateNameMakerBaseASCIICharSet(string namePrefix, int seed)
         {
             var words = new List<string>();
             for (int i = 0; i < 26; i++)
@@ -37,7 +42,7 @@ namespace Obfuz.ObfusPasses.SymbolObfus.NameMakers
                 words.Add(((char)('a' + i)).ToString());
                 words.Add(((char)('A' + i)).ToString());
             }
-            return new WordSetNameMaker(namePrefix, words);
+            return new WordSetNameMaker(namePrefix, words, seed);
         }
     }
 }

Editor/ObfusPasses/SymbolObfus/NameMakers/NameScope.cs

@@ -1,4 +1,4 @@
-// Copyright 2025 Code Philosophy
+// Copyright 2025 Code Philosophy
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -28,19 +28,35 @@ namespace Obfuz.ObfusPasses.SymbolObfus.NameMakers
     {
         private readonly string _namePrefix;
         private readonly List<string> _wordSet;
+        private readonly System.Random _random;
+        private readonly int _nameSpace;
         private int _nextIndex;
 
-        public NameScope(string namePrefix, List<string> wordSet)
+        public NameScope(string namePrefix, List<string> wordSet) : this(namePrefix, wordSet, 0)
+        {
+        }
+
+        // A zero seed keeps the original deterministic base-N counter. Any other seed draws
+        // names at random from a space wide enough that collisions are rare; NameScopeBase
+        // retries on collision, so correctness does not depend on the space being large.
+        public NameScope(string namePrefix, List<string> wordSet, int seed)
         {
             _namePrefix = namePrefix;
             _wordSet = wordSet;
             _nextIndex = 0;
+            _random = seed != 0 ? new System.Random(seed) : null;
+            int space = 1;
+            for (int i = 0; i < 4; i++)
+            {
+                space *= wordSet.Count;
+            }
+            _nameSpace = space;
         }
 
         protected override void BuildNewName(StringBuilder nameBuilder, string originalName, string lastName)
         {
             nameBuilder.Append(_namePrefix);
-            for (int i = _nextIndex++; ;)
+            for (int i = _random != null ? _random.Next(_nameSpace) : _nextIndex++; ;)
             {
                 nameBuilder.Append(_wordSet[i % _wordSet.Count]);
                 i = i / _wordSet.Count;

Editor/ObfusPasses/SymbolObfus/NameMakers/WordSetNameMaker.cs

@@ -1,4 +1,4 @@
-// Copyright 2025 Code Philosophy
+// Copyright 2025 Code Philosophy
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -27,16 +27,30 @@ namespace Obfuz.ObfusPasses.SymbolObfus.NameMakers
     {
         private readonly string _namePrefix;
         private readonly List<string> _wordSet;
+        private readonly int _seed;
+        private int _scopeIndex;
 
-        public WordSetNameMaker(string namePrefix, List<string> wordSet)
+        public WordSetNameMaker(string namePrefix, List<string> wordSet) : this(namePrefix, wordSet, 0)
+        {
+        }
+
+        public WordSetNameMaker(string namePrefix, List<string> wordSet, int seed)
         {
             _namePrefix = namePrefix;
             _wordSet = wordSet;
+            _seed = seed;
         }
 
         protected override INameScope CreateNameScope()
+        {
+            if (_seed == 0)
             {
                 return new NameScope(_namePrefix, _wordSet);
             }
+
+            // Distinct per scope, otherwise every scope would emit the same sequence.
+            int scopeSeed = unchecked(_seed + _scopeIndex++ * (int)0x9E3779B9);
+            return new NameScope(_namePrefix, _wordSet, scopeSeed != 0 ? scopeSeed : 1);
+        }
     }
 }

Editor/ObfusPasses/SymbolObfus/SymbolRename.cs

@@ -1,4 +1,4 @@
-// Copyright 2025 Code Philosophy
+// Copyright 2025 Code Philosophy
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -66,7 +66,7 @@ namespace Obfuz.ObfusPasses.SymbolObfus
             _obfuscationRuleFiles = settings.ruleFiles.ToList();
             _renameRecordMap = new RenameRecordMap(settings.symbolMappingFile, settings.debug, settings.keepUnknownSymbolInSymbolMappingFile);
             _virtualMethodGroupCalculator = new VirtualMethodGroupCalculator();
-            _nameMaker = settings.debug ? NameMakerFactory.CreateDebugNameMaker() : NameMakerFactory.CreateNameMakerBaseASCIICharSet(settings.obfuscatedNamePrefix);
+            _nameMaker = settings.debug ? NameMakerFactory.CreateDebugNameMaker() : NameMakerFactory.CreateNameMakerBaseASCIICharSet(settings.obfuscatedNamePrefix, settings.nameRandomSeed);
             _customPolicyTypes = settings.customRenamePolicyTypes;
         }
 

Editor/Settings/SymbolObfuscationSettings.cs

@@ -1,4 +1,4 @@
-// Copyright 2025 Code Philosophy
+// Copyright 2025 Code Philosophy
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -34,6 +34,7 @@ namespace Obfuz.Settings
         public bool detectReflectionCompatibility;
         public bool keepUnknownSymbolInSymbolMappingFile;
         public string symbolMappingFile;
+        public int nameRandomSeed;
         public List<string> ruleFiles;
         public List<Type> customRenamePolicyTypes;
     }
@@ -58,6 +59,9 @@ namespace Obfuz.Settings
         [Tooltip("symbol mapping file path")]
         public string symbolMappingFile = "Assets/Obfuz/SymbolObfus/symbol-mapping.xml";
 
+        [Tooltip("random seed for generated names. 0 keeps the original deterministic sequence; any other value randomises which name each symbol gets, so the mapping differs between builds")]
+        public int nameRandomSeed = 0;
+
         [Tooltip("debug symbol mapping file path, used for debugging purposes")]
         public string debugSymbolMappingFile = "Assets/Obfuz/SymbolObfus/symbol-mapping-debug.xml";
 
@@ -82,6 +86,7 @@ namespace Obfuz.Settings
                 detectReflectionCompatibility = detectReflectionCompatibility,
                 keepUnknownSymbolInSymbolMappingFile = keepUnknownSymbolInSymbolMappingFile,
                 symbolMappingFile = GetSymbolMappingFile(),
+                nameRandomSeed = nameRandomSeed,
                 ruleFiles = ruleFiles?.ToList() ?? new List<string>(),
                 customRenamePolicyTypes = customRenamePolicyTypes?.Select(typeName => ReflectionUtil.FindUniqueTypeInCurrentAppDomain(typeName)).ToList() ?? new List<Type>(),
             };