diff --git a/Editor/Emit/ConstFieldAllocator.cs b/Editor/Emit/ConstFieldAllocator.cs
new file mode 100644
index 0000000..a3c2894
--- /dev/null
+++ b/Editor/Emit/ConstFieldAllocator.cs
@@ -0,0 +1,233 @@
+using dnlib.DotNet;
+using dnlib.DotNet.Emit;
+using Obfuz.Utils;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using UnityEngine.Assertions;
+
+namespace Obfuz.Emit
+{
+    public class ModuleConstFieldAllocator
+    {
+        private readonly ModuleDef _module;
+        private readonly IRandom _random;
+
+        private TypeDef _holderTypeDef;
+
+        class ConstFieldInfo
+        {
+            public FieldDef field;
+            public object value;
+        }
+        private readonly Dictionary<object, ConstFieldInfo> _allocatedFields = new Dictionary<object, ConstFieldInfo>();
+        private readonly Dictionary<FieldDef, ConstFieldInfo> _field2Fields = new Dictionary<FieldDef, ConstFieldInfo>();
+
+        private readonly List<TypeDef> _holderTypeDefs = new List<TypeDef>();
+
+
+        public ModuleConstFieldAllocator(ModuleDef mod, IRandom random)
+        {
+            _module = mod;
+            _random = random;
+        }
+
+        const int maxFieldCount = 1000;
+
+
+        private TypeSig GetTypeSigOfValue(object value)
+        {
+            if (value is int)
+                return _module.CorLibTypes.Int32;
+            if (value is long)
+                return _module.CorLibTypes.Int64;
+            if (value is float)
+                return _module.CorLibTypes.Single;
+            if (value is double)
+                return _module.CorLibTypes.Double;
+            if (value is string)
+                return _module.CorLibTypes.String;
+            if (value is byte[])
+                return new SZArraySig(_module.CorLibTypes.Byte);
+            throw new NotSupportedException($"Unsupported type: {value.GetType()}");
+        }
+
+        private ConstFieldInfo CreateConstFieldInfo(object value)
+        {
+            if (_holderTypeDef == null || _holderTypeDef.Fields.Count >= maxFieldCount)
+            {
+                _module.EnableTypeDefFindCache = false;
+                ITypeDefOrRef objectTypeRef = _module.Import(typeof(object));
+                _holderTypeDef = new TypeDefUser("$Obfuz$ConstFieldHolder$", objectTypeRef);
+                _module.Types.Add(_holderTypeDef);
+                _holderTypeDefs.Add(_holderTypeDef);
+                _module.EnableTypeDefFindCache = true;
+            }
+
+            var field = new FieldDefUser($"$RVA_Value{_holderTypeDef.Fields.Count}", new FieldSig(GetTypeSigOfValue(value)), FieldAttributes.Static | FieldAttributes.Private | FieldAttributes.InitOnly);
+            field.DeclaringType = _holderTypeDef;
+            return new ConstFieldInfo
+            {
+                field = field,
+                value = value,
+            };
+        }
+
+        private FieldDef AllocateAny(object value)
+        {
+            if (!_allocatedFields.TryGetValue(value, out var field))
+            {
+                field = CreateConstFieldInfo(value);
+                _allocatedFields.Add(value, field);
+                _field2Fields.Add(field.field, field);
+            }
+            return field.field;
+        }
+
+        public FieldDef Allocate(int value)
+        {
+            return AllocateAny(value);
+        }
+
+        public FieldDef Allocate(long value)
+        {
+            return AllocateAny(value);
+        }
+
+        public FieldDef Allocate(float value)
+        {
+            return AllocateAny(value);
+        }
+
+        public FieldDef Allocate(double value)
+        {
+            return AllocateAny(value);
+        }
+
+        public FieldDef Allocate(string value)
+        {
+            return AllocateAny(value);
+        }
+
+        //public FieldDef Allocate(byte[] value)
+        //{
+        //    throw new NotImplementedException();
+        //}
+
+        private void CreateCCtorOfRvaTypeDef(TypeDef type)
+        {
+            var cctor = new MethodDefUser(".cctor",
+                MethodSig.CreateStatic(_module.CorLibTypes.Void),
+                MethodImplAttributes.IL | MethodImplAttributes.Managed,
+                MethodAttributes.Static | MethodAttributes.HideBySig | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName | MethodAttributes.Private);
+            cctor.DeclaringType = type;
+            //_rvaTypeDef.Methods.Add(cctor);
+            var body = new CilBody();
+            cctor.Body = body;
+            var ins = body.Instructions;
+
+            //IMethod method = _module.Import(typeof(System.Runtime.CompilerServices.RuntimeHelpers).GetMethod("InitializeArray", new[] { typeof(Array), typeof(RuntimeFieldHandle) }));
+            //Assert.IsNotNull(method);
+
+            // TODO. obfuscate init codes
+            foreach (var field in type.Fields)
+            {
+                ConstFieldInfo constInfo = _field2Fields[field];
+                switch (constInfo.value)
+                {
+                    case int i:
+                    ins.Add(Instruction.Create(OpCodes.Ldc_I4, i));
+                    break;
+                    case long l:
+                    ins.Add(Instruction.Create(OpCodes.Ldc_I8, l));
+                    break;
+                    case float f:
+                    ins.Add(Instruction.Create(OpCodes.Ldc_R4, f));
+                    break;
+                    case double d:
+                    ins.Add(Instruction.Create(OpCodes.Ldc_R8, d));
+                    break;
+                    case string s:
+                    ins.Add(Instruction.Create(OpCodes.Ldstr, s));
+                    break;
+                    //case byte[] b:
+                    //    ins.Add(Instruction.Create(OpCodes.Ldlen, b.Length));
+                    //    break;
+                    default: throw new NotSupportedException($"Unsupported type: {constInfo.value.GetType()}");
+                }
+                ins.Add(Instruction.Create(OpCodes.Stsfld, field));
+            }
+            ins.Add(Instruction.Create(OpCodes.Ret));
+        }
+
+        public void Done()
+        {
+            foreach (var typeDef in _holderTypeDefs)
+            {
+                CreateCCtorOfRvaTypeDef(typeDef);
+            }
+        }
+    }
+
+    public class ConstFieldAllocator
+    {
+        private readonly IRandom _random;
+
+        private readonly Dictionary<ModuleDef, ModuleConstFieldAllocator> _moduleAllocators = new Dictionary<ModuleDef, ModuleConstFieldAllocator>();
+
+        public ConstFieldAllocator(IRandom random)
+        {
+            _random = random;
+        }
+
+        private ModuleConstFieldAllocator GetModuleAllocator(ModuleDef mod)
+        {
+            if (!_moduleAllocators.TryGetValue(mod, out var moduleAllocator))
+            {
+                moduleAllocator = new ModuleConstFieldAllocator(mod, _random);
+                _moduleAllocators[mod] = moduleAllocator;
+            }
+            return moduleAllocator;
+        }
+
+        public FieldDef Allocate(ModuleDef mod, int value)
+        {
+            return GetModuleAllocator(mod).Allocate(value);
+        }
+
+        public FieldDef Allocate(ModuleDef mod, long value)
+        {
+            return GetModuleAllocator(mod).Allocate(value);
+        }
+
+        public FieldDef Allocate(ModuleDef mod, float value)
+        {
+            return GetModuleAllocator(mod).Allocate(value);
+        }
+
+        public FieldDef Allocate(ModuleDef mod, double value)
+        {
+            return GetModuleAllocator(mod).Allocate(value);
+        }
+
+        public FieldDef Allocate(ModuleDef mod, string value)
+        {
+            return GetModuleAllocator(mod).Allocate(value);
+        }
+
+        public void Done()
+        {
+            foreach (var moduleAllocator in _moduleAllocators.Values)
+            {
+                moduleAllocator.Done();
+            }
+        }
+
+        //public FieldDef Allocate(ModuleDef mod, byte[] value)
+        //{
+        //    return GetModuleAllocator(mod).Allocate(value);
+        //}
+    }
+}
diff --git a/Editor/Virtualization/CompileContext.cs b/Editor/Virtualization/CompileContext.cs
index 6a30ad4..75e3a86 100644
--- a/Editor/Virtualization/CompileContext.cs
+++ b/Editor/Virtualization/CompileContext.cs
@@ -11,5 +11,6 @@ namespace Obfuz.Virtualization
         public MethodDef method;
         public List<Instruction> output;
         public RvaDataAllocator rvaDataAllocator;
+        public ConstFieldAllocator constFieldAllocator;
     }
 }
diff --git a/Editor/Virtualization/DataNodes/ConstFieldDataNode.cs b/Editor/Virtualization/DataNodes/ConstFieldDataNode.cs
index 65d80bc..3c3926a 100644
--- a/Editor/Virtualization/DataNodes/ConstFieldDataNode.cs
+++ b/Editor/Virtualization/DataNodes/ConstFieldDataNode.cs
@@ -1,4 +1,7 @@
-using System;
+using dnlib.DotNet;
+using dnlib.DotNet.Emit;
+using System;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 
 namespace Obfuz.Virtualization
@@ -8,36 +11,34 @@ namespace Obfuz.Virtualization
 
         public override void Compile(CompileContext ctx)
         {
+            ModuleDef mod = ctx.method.Module;
+            var output = ctx.output;
+            FieldDef field;
             switch (Type)
             {
-                //case DataNodeType.Byte:
-                //{
-                //    // create ldloc.i4 
-                //    break;
-                //}
                 case DataNodeType.Int32:
                 {
-                    // create ldloc.i4
+                    field = ctx.constFieldAllocator.Allocate(mod, IntValue);
                     break;
                 }
                 case DataNodeType.Int64:
                 {
-                    // create ldloc.i8
+                    field = ctx.constFieldAllocator.Allocate(mod, LongValue);
                     break;
                 }
                 case DataNodeType.Float32:
                 {
-                    // create ldloc.r4
+                    field = ctx.constFieldAllocator.Allocate(mod, FloatValue);
                     break;
                 }
                 case DataNodeType.Float64:
                 {
-                    // create ldloc.r8
+                    field = ctx.constFieldAllocator.Allocate(mod, DoubleValue);
                     break;
                 }
                 case DataNodeType.String:
                 {
-                    // create ldstr
+                    field = ctx.constFieldAllocator.Allocate(mod, StringValue);
                     break;
                 }
                 case DataNodeType.Bytes:
@@ -45,13 +46,15 @@ namespace Obfuz.Virtualization
                     // ldsfld 
                     // ldtoken 
                     // RuntimeHelpers.InitializeArray(array, fieldHandle);
-                    break;
+                    //break;
+                    throw new NotSupportedException("Bytes not supported");
                 }
                 default:
                 {
                     throw new NotImplementedException($"Type:{Type} not implemented");
                 }
             }
+            output.Add(Instruction.Create(OpCodes.Ldsfld, field));
         }
     }
 }
diff --git a/Editor/Virtualization/DefaultDataObfuscator.cs b/Editor/Virtualization/DefaultDataObfuscator.cs
index 9ad00f7..9be395d 100644
--- a/Editor/Virtualization/DefaultDataObfuscator.cs
+++ b/Editor/Virtualization/DefaultDataObfuscator.cs
@@ -12,12 +12,14 @@ namespace Obfuz.Virtualization
         private readonly IRandom _random;
         private readonly RandomDataNodeCreator _nodeCreator;
         private readonly RvaDataAllocator _rvaDataAllocator;
+        private readonly ConstFieldAllocator _constFieldAllocator;
 
         public DefaultDataObfuscator()
         {
             _random = new RandomWithKey(new byte[] { 0x1, 0x2, 0x3, 0x4 }, 0x5);
             _nodeCreator = new RandomDataNodeCreator(_random);
             _rvaDataAllocator = new RvaDataAllocator(_random);
+            _constFieldAllocator = new ConstFieldAllocator(_random);
         }
 
         private void CompileNode(IDataNode node, MethodDef method, List<Instruction> obfuscatedInstructions)
@@ -27,6 +29,7 @@ namespace Obfuz.Virtualization
                 method = method,
                 output = obfuscatedInstructions,
                 rvaDataAllocator = _rvaDataAllocator,
+                constFieldAllocator = _constFieldAllocator,
             };
             node.Compile(ctx);
         }
@@ -67,14 +70,15 @@ namespace Obfuz.Virtualization
 
         public void ObfuscateString(MethodDef method, string value, List<Instruction> obfuscatedInstructions)
         {
-            //IDataNode node = _nodeCreator.CreateRandom(DataNodeType.String, value);
-            //CompileNode(node, method, obfuscatedInstructions);
-            obfuscatedInstructions.Add(Instruction.Create(OpCodes.Ldstr, value));
+            IDataNode node = _nodeCreator.CreateRandom(DataNodeType.String, value);
+            CompileNode(node, method, obfuscatedInstructions);
+            //obfuscatedInstructions.Add(Instruction.Create(OpCodes.Ldstr, value));
         }
 
         public void Stop()
         {
             _rvaDataAllocator.Done();
+            _constFieldAllocator.Done();
         }
     }
 }
diff --git a/Editor/Virtualization/Functions/ConstFieldDataCreator.cs b/Editor/Virtualization/Functions/ConstFieldDataCreator.cs
new file mode 100644
index 0000000..22c128d
--- /dev/null
+++ b/Editor/Virtualization/Functions/ConstFieldDataCreator.cs
@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Obfuz.Virtualization.Functions
+{
+    public class ConstFieldDataCreator : NodeCreatorBase
+    {
+        public override IDataNode CreateExpr(DataNodeType type, object value, CreateExpressionOptions options)
+        {
+            return new ConstFieldDataNode { Type = type, Value = value };
+        }
+    }
+}
diff --git a/Editor/Virtualization/Functions/IntAdd.cs b/Editor/Virtualization/Functions/IntAdd.cs
index d9296db..9b2fa25 100644
--- a/Editor/Virtualization/Functions/IntAdd.cs
+++ b/Editor/Virtualization/Functions/IntAdd.cs
@@ -5,7 +5,6 @@ using System.Data;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
-using static UnityEngine.Networking.UnityWebRequest;
 
 namespace Obfuz.Virtualization.Functions
 {
diff --git a/Editor/Virtualization/RandomDataNodeCreator.cs b/Editor/Virtualization/RandomDataNodeCreator.cs
index ccac00f..5946421 100644
--- a/Editor/Virtualization/RandomDataNodeCreator.cs
+++ b/Editor/Virtualization/RandomDataNodeCreator.cs
@@ -32,6 +32,12 @@ namespace Obfuz.Virtualization
             };
             _functions.Add(DataNodeType.Float32, floatFuncs);
             _functions.Add(DataNodeType.Float64, floatFuncs);
+
+            var stringFuncs = new List<IFunction>()
+            {
+                new ConstFieldDataCreator(),
+            };
+            _functions.Add(DataNodeType.String, stringFuncs);
         }
 
         public override IDataNode CreateRandom(DataNodeType type, object value, CreateExpressionOptions options)