109 lines
4.4 KiB
C#
109 lines
4.4 KiB
C#
using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using Obfuz.Emit;
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using Obfuz.Utils;
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using System;
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using System.Collections.Generic;
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using UnityEngine.Assertions;
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namespace Obfuz.MemEncrypt
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{
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public class DefaultMemoryEncryptor : MemoryEncryptorBase
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{
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private class ModuleDefaultMemoryEncryptor
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{
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private readonly ModuleDef _module;
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public ModuleDefaultMemoryEncryptor(ModuleDef module)
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{
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_module = module;
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InitMetadatas(module);
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}
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private static IMethod s_castIntAsFloat;
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private static IMethod s_castLongAsDouble;
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private static IMethod s_castFloatAsInt;
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private static IMethod s_castDoubleAsLong;
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private void InitMetadatas(ModuleDef mod)
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{
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if (s_castFloatAsInt != null)
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{
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return;
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}
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var constUtilityType = typeof(ConstUtility);
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s_castIntAsFloat = mod.Import(constUtilityType.GetMethod("CastIntAsFloat"));
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Assert.IsNotNull(s_castIntAsFloat, "CastIntAsFloat not found");
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s_castLongAsDouble = mod.Import(constUtilityType.GetMethod("CastLongAsDouble"));
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Assert.IsNotNull(s_castLongAsDouble, "CastLongAsDouble not found");
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s_castFloatAsInt = mod.Import(constUtilityType.GetMethod("CastFloatAsInt"));
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Assert.IsNotNull(s_castFloatAsInt, "CastFloatAsInt not found");
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s_castDoubleAsLong = mod.Import(constUtilityType.GetMethod("CastDoubleAsLong"));
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Assert.IsNotNull(s_castDoubleAsLong, "CastDoubleAsLong not found");
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}
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private VariableEncryption CreateEncryption(ElementType type)
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{
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IRandom random = new RandomWithKey(new byte[16], 1234);
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switch (type)
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{
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case ElementType.I4:
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return new VariableEncryption(DataNodeType.Int32, random);
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case ElementType.I8:
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return new VariableEncryption(DataNodeType.Int64, random);
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case ElementType.R4:
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return new VariableEncryption(DataNodeType.Float32, random);
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case ElementType.R8:
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return new VariableEncryption(DataNodeType.Float64, random);
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default: throw new Exception($"Unsupported type {type} for MemoryEncryptor");
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}
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}
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public void Encrypt(FieldDef field, List<Instruction> outputInstructions, MemoryEncryptionContext ctx)
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{
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ElementType type = field.FieldType.RemovePinnedAndModifiers().ElementType;
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var encryption = CreateEncryption(type);
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encryption.EmitTransform(outputInstructions, new EncryptionCompileContext { module = _module });
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outputInstructions.Add(ctx.currentInstruction.Clone());
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}
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public void Decrypt(FieldDef field, List<Instruction> outputInstructions, MemoryEncryptionContext ctx)
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{
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outputInstructions.Add(ctx.currentInstruction.Clone());
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ElementType type = field.FieldType.RemovePinnedAndModifiers().ElementType;
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var encryption = CreateEncryption(type);
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encryption.EmitRevertTransform(outputInstructions, new EncryptionCompileContext { module = _module });
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}
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}
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private readonly Dictionary<ModuleDef, ModuleDefaultMemoryEncryptor> _moduleEncryptors = new Dictionary<ModuleDef, ModuleDefaultMemoryEncryptor>();
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private ModuleDefaultMemoryEncryptor GetModuleEncryptor(ModuleDef module)
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{
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if (!_moduleEncryptors.TryGetValue(module, out var encryptor))
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{
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encryptor = new ModuleDefaultMemoryEncryptor(module);
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_moduleEncryptors.Add(module, encryptor);
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}
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return encryptor;
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}
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public override void Encrypt(FieldDef field, List<Instruction> outputInstructions, MemoryEncryptionContext ctx)
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{
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GetModuleEncryptor(ctx.module).Encrypt(field, outputInstructions, ctx);
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}
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public override void Decrypt(FieldDef field, List<Instruction> outputInstructions, MemoryEncryptionContext ctx)
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{
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GetModuleEncryptor(ctx.module).Decrypt(field, outputInstructions, ctx);
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}
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}
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}
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