88 lines
3.3 KiB
C#
88 lines
3.3 KiB
C#
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using Pulsar.Server.Build.Obfuscator.Utils;
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using Pulsar.Server.Build.Obfuscator.Utils.Injection;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Reflection;
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using System.Security.Cryptography;
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using System.Text;
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using System.Threading.Tasks;
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using System.Windows.Forms;
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namespace Pulsar.Server.Build.Obfuscator.Transformers
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{
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public class StringEncryptionTransformer : ITransformer
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{
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public MethodDef InjectDecryptionMethod(ModuleDefMD module)
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{
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// create our type holding our string decryption method
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TypeDef stringType = new TypeDefUser("", RandomUTFString(10), module.CorLibTypes.Object.TypeDefOrRef);
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module.Types.Add(stringType);
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// inject the methods we want to it
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ModuleDefMD typeModule = ModuleDefMD.Load(typeof(StringEncryption).Module);
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TypeDef typeDef = typeModule.ResolveTypeDef(MDToken.ToRID(typeof(StringEncryption).MetadataToken));
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IEnumerable<IDnlibDef> members = InjectHelper.Inject(typeDef, stringType, module);
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MethodDef decryptMethod = (MethodDef)members.Single(method => method.Name == "Decrypt");
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decryptMethod.Name = RandomUTFString(10);
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// remove the Encrypt method
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stringType.Methods.Remove(stringType.Methods.Single(method => method.Name == "Encrypt"));
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return decryptMethod;
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}
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public override void Transform(Obfuscator obf)
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{
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// Inject the Decrypt method into the type
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MethodDef decryptMethod = InjectDecryptionMethod(obf.Module);
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foreach (TypeDef type in obf.Module.GetTypes())
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{
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if (type.FullName.StartsWith("NAudio")) continue;
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foreach (MethodDef method in type.Methods)
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{
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if (!method.HasBody) continue;
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method.Body.SimplifyBranches();
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for (int i = 0; i < method.Body.Instructions.Count; i++)
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{
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if (method.Body.Instructions[i].OpCode == OpCodes.Ldstr)
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{
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object op = method.Body.Instructions[i].Operand;
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if (op is string)
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{
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AesManaged aes = new AesManaged();
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string key = Convert.ToBase64String(aes.Key);
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string iv = Convert.ToBase64String(aes.IV);
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string encrypted = StringEncryption.Encrypt((string)op, aes.Key, aes.IV);
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// Call to decrypt(value, key, iv);
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method.Body.Instructions[i].Operand = encrypted;
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method.Body.Instructions.Insert(i + 1, OpCodes.Ldstr.ToInstruction(key));
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method.Body.Instructions.Insert(i + 2, OpCodes.Ldstr.ToInstruction(iv));
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method.Body.Instructions.Insert(i + 3, OpCodes.Call.ToInstruction(decryptMethod));
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i += 3; // skip the added instructions
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}
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}
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}
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}
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}
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}
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}
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}
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