426 lines
12 KiB
C#
426 lines
12 KiB
C#
/*
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Copyright (C) 2011-2012 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using System.IO;
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using dot10.DotNet;
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using dot10.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Confuser {
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class ResourceDecrypter : IVersionProvider {
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ModuleDefMD module;
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ISimpleDeobfuscator simpleDeobfuscator;
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MethodDef handler;
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MethodDef installMethod;
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EmbeddedResource resource;
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Dictionary<FieldDef, bool> fields = new Dictionary<FieldDef, bool>();
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byte key0, key1;
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ConfuserVersion version = ConfuserVersion.Unknown;
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enum ConfuserVersion {
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Unknown,
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v14_r55802,
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v17_r73404,
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v17_r73822,
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v18_r75367,
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v18_r75369,
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}
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public IEnumerable<FieldDef> Fields {
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get { return fields.Keys; }
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}
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public MethodDef Handler {
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get { return handler; }
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}
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public bool Detected {
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get { return handler != null; }
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}
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public ResourceDecrypter(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator) {
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this.module = module;
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this.simpleDeobfuscator = simpleDeobfuscator;
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}
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public void find() {
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if (checkMethod(DotNetUtils.getModuleTypeCctor(module)))
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return;
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}
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bool checkMethod(MethodDef method) {
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if (method == null || method.Body == null)
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return false;
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if (!DotNetUtils.callsMethod(method, "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)"))
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return false;
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simpleDeobfuscator.deobfuscate(method, true);
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fields.Clear();
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var tmpHandler = getHandler(method);
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if (tmpHandler == null || tmpHandler.DeclaringType != method.DeclaringType)
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return false;
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var tmpResource = findResource(tmpHandler);
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if (tmpResource == null)
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return false;
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simpleDeobfuscator.deobfuscate(tmpHandler, true);
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ConfuserVersion tmpVersion = ConfuserVersion.Unknown;
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if (DotNetUtils.callsMethod(tmpHandler, "System.Object System.AppDomain::GetData(System.String)")) {
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if (!DotNetUtils.callsMethod(tmpHandler, "System.Void System.Buffer::BlockCopy(System.Array,System.Int32,System.Array,System.Int32,System.Int32)")) {
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if (!findKey0Key1_v14_r55802(tmpHandler, out key0, out key1))
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return false;
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tmpVersion = ConfuserVersion.v14_r55802;
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}
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else if (findKey0_v17_r73404(tmpHandler, out key0) && findKey1_v17_r73404(tmpHandler, out key1))
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tmpVersion = ConfuserVersion.v17_r73404;
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else
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return false;
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}
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else {
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if (addFields(findFields(tmpHandler, method.DeclaringType)) != 1)
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return false;
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if (findKey0_v17_r73404(tmpHandler, out key0) && findKey1_v17_r73404(tmpHandler, out key1))
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tmpVersion = ConfuserVersion.v17_r73822;
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else if (findKey0_v18_r75367(tmpHandler, out key0) && findKey1_v17_r73404(tmpHandler, out key1))
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tmpVersion = ConfuserVersion.v18_r75367;
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else if (findKey0_v18_r75369(tmpHandler, out key0) && findKey1_v18_r75369(tmpHandler, out key1))
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tmpVersion = ConfuserVersion.v18_r75369;
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else
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return false;
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}
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handler = tmpHandler;
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resource = tmpResource;
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installMethod = method;
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version = tmpVersion;
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return true;
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}
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static MethodDef getHandler(MethodDef method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 2; i++) {
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var ldftn = instrs[i];
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if (ldftn.OpCode.Code != Code.Ldftn)
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continue;
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var handler = ldftn.Operand as MethodDef;
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if (handler == null)
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continue;
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var newobj = instrs[i + 1];
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if (newobj.OpCode.Code != Code.Newobj)
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continue;
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var callvirt = instrs[i + 2];
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if (callvirt.OpCode.Code != Code.Callvirt)
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continue;
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var calledMethod = callvirt.Operand as IMethod;
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if (calledMethod == null)
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continue;
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if (calledMethod.FullName != "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)")
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continue;
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return handler;
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}
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return null;
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}
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int addFields(IEnumerable<FieldDef> moreFields) {
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int count = 0;
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foreach (var field in moreFields) {
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if (addField(field))
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count++;
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}
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return count;
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}
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bool addField(FieldDef field) {
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if (field == null)
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return false;
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if (fields.ContainsKey(field))
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return false;
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fields[field] = true;
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return true;
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}
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static IEnumerable<FieldDef> findFields(MethodDef method, TypeDef declaringType) {
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var fields = new List<FieldDef>();
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foreach (var instr in method.Body.Instructions) {
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var field = instr.Operand as FieldDef;
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if (field != null && field.DeclaringType == declaringType)
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fields.Add(field);
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}
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return fields;
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}
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EmbeddedResource findResource(MethodDef method) {
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return DotNetUtils.getResource(module, DotNetUtils.getCodeStrings(method)) as EmbeddedResource;
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}
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static bool findKey0_v18_r75367(MethodDef method, out byte key0) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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i = ConfuserUtils.findCallMethod(instrs, i, Code.Callvirt, "System.Int32 System.IO.Stream::Read(System.Byte[],System.Int32,System.Int32)");
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if (i < 0)
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break;
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if (i + 3 >= instrs.Count)
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break;
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if (instrs[i + 1].OpCode.Code != Code.Pop)
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continue;
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var ldci4 = instrs[i + 2];
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if (!ldci4.IsLdcI4())
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continue;
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if (!instrs[i + 3].IsStloc())
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continue;
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key0 = (byte)ldci4.GetLdcI4Value();
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return true;
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}
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key0 = 0;
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return false;
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}
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static bool findKey0_v18_r75369(MethodDef method, out byte key0) {
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var instrs = method.Body.Instructions;
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for (int index = 0; index < instrs.Count; index++) {
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index = ConfuserUtils.findCallMethod(instrs, index, Code.Callvirt, "System.Int32 System.IO.Stream::Read(System.Byte[],System.Int32,System.Int32)");
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if (index < 0)
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break;
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if (index + 4 >= instrs.Count)
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break;
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index++;
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if (instrs[index++].OpCode.Code != Code.Pop)
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continue;
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var ldci4 = instrs[index++];
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if (!ldci4.IsLdcI4())
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continue;
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if (instrs[index++].OpCode.Code != Code.Conv_U1)
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continue;
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if (!instrs[index++].IsStloc())
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continue;
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key0 = (byte)ldci4.GetLdcI4Value();
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return true;
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}
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key0 = 0;
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return false;
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}
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static bool findKey1_v18_r75369(MethodDef method, out byte key1) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 4; i++) {
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int index = i;
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if (!instrs[index++].IsLdloc())
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continue;
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var ldci4_1 = instrs[index++];
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if (!ldci4_1.IsLdcI4())
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continue;
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if (instrs[index++].OpCode.Code != Code.Mul)
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continue;
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var ldci4_2 = instrs[index++];
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if (!ldci4_2.IsLdcI4() || ldci4_2.GetLdcI4Value() != 0x100)
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continue;
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if (instrs[index++].OpCode.Code != Code.Rem)
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continue;
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key1 = (byte)ldci4_1.GetLdcI4Value();
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return true;
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}
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key1 = 0;
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return false;
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}
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static bool findKey0Key1_v14_r55802(MethodDef method, out byte key0, out byte key1) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 5; i++) {
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if (!instrs[i].IsLdcI4())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Add)
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continue;
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if (instrs[i + 2].OpCode.Code != Code.Ldelem_U1)
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continue;
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var ldci4_1 = instrs[i + 3];
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if (!ldci4_1.IsLdcI4())
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continue;
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if (instrs[i + 4].OpCode.Code != Code.Xor)
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continue;
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var ldci4_2 = instrs[i + 5];
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if (!ldci4_2.IsLdcI4())
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continue;
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key0 = (byte)ldci4_1.GetLdcI4Value();
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key1 = (byte)ldci4_2.GetLdcI4Value();
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return true;
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}
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key0 = 0;
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key1 = 0;
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return false;
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}
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static bool findKey0_v17_r73404(MethodDef method, out byte key) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 3; i++) {
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int index = ConfuserUtils.findCallMethod(instrs, i, Code.Callvirt, "System.Byte[] System.IO.BinaryReader::ReadBytes(System.Int32)");
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if (index < 0)
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break;
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if (index + 3 >= instrs.Count)
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break;
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if (!instrs[index + 1].IsStloc())
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continue;
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var ldci4 = instrs[index + 2];
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if (!ldci4.IsLdcI4())
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continue;
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if (!instrs[index + 3].IsStloc())
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continue;
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key = (byte)ldci4.GetLdcI4Value();
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return true;
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}
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key = 0;
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return false;
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}
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static bool findKey1_v17_r73404(MethodDef method, out byte key) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 3; i++) {
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var ldci4_1 = instrs[i];
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if (!ldci4_1.IsLdcI4())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Mul)
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continue;
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var ldci4_2 = instrs[i + 2];
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if (!ldci4_2.IsLdcI4() || ldci4_2.GetLdcI4Value() != 0x100)
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continue;
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if (instrs[i + 3].OpCode.Code != Code.Rem)
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continue;
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key = (byte)ldci4_1.GetLdcI4Value();
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return true;
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}
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key = 0;
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return false;
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}
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public EmbeddedResource mergeResources() {
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if (resource == null)
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return null;
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DeobUtils.decryptAndAddResources(module, resource.Name.String, () => decryptResource());
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var tmpResource = resource;
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resource = null;
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return tmpResource;
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}
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byte[] decryptResource() {
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switch (version) {
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case ConfuserVersion.v14_r55802: return decrypt_v14_r55802();
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case ConfuserVersion.v17_r73404: return decrypt_v17_r73404();
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case ConfuserVersion.v17_r73822: return decrypt_v17_r73404();
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case ConfuserVersion.v18_r75367: return decrypt_v18_r75367();
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case ConfuserVersion.v18_r75369: return decrypt_v18_r75367();
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default: throw new ApplicationException("Unknown version");
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}
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}
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byte[] decrypt_v14_r55802() {
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var reader = new BinaryReader(new MemoryStream(DeobUtils.inflate(resource.GetResourceData(), true)));
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var encypted = reader.ReadBytes(reader.ReadInt32());
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if ((encypted.Length & 1) != 0)
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throw new ApplicationException("Invalid resource data length");
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var decrypted = new byte[encypted.Length / 2];
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for (int i = 0; i < decrypted.Length; i++)
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decrypted[i] = (byte)((encypted[i * 2 + 1] ^ key0) * key1 + (encypted[i * 2] ^ key0));
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reader = new BinaryReader(new MemoryStream(DeobUtils.inflate(decrypted, true)));
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return reader.ReadBytes(reader.ReadInt32());
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}
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byte[] decrypt_v17_r73404() {
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var reader = new BinaryReader(new MemoryStream(DeobUtils.inflate(resource.GetResourceData(), true)));
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var decrypted = reader.ReadBytes(reader.ReadInt32());
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byte k = key0;
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for (int i = 0; i < decrypted.Length; i++) {
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decrypted[i] ^= k;
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k *= key1;
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}
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return decrypted;
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}
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byte[] decrypt_v18_r75367() {
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var encrypted = resource.GetResourceData();
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byte k = key0;
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for (int i = 0; i < encrypted.Length; i++) {
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encrypted[i] ^= k;
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k *= key1;
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}
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var reader = new BinaryReader(new MemoryStream(DeobUtils.inflate(encrypted, true)));
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return reader.ReadBytes(reader.ReadInt32());
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}
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public void deobfuscate(Blocks blocks) {
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if (blocks.Method != installMethod)
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return;
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ConfuserUtils.removeResourceHookCode(blocks, handler);
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}
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public bool getRevisionRange(out int minRev, out int maxRev) {
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switch (version) {
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case ConfuserVersion.Unknown:
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minRev = maxRev = 0;
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return false;
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case ConfuserVersion.v14_r55802:
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minRev = 55802;
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maxRev = 72989;
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return true;
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case ConfuserVersion.v17_r73404:
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minRev = 73404;
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maxRev = 73791;
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return true;
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case ConfuserVersion.v17_r73822:
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minRev = 73822;
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maxRev = 75349;
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return true;
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case ConfuserVersion.v18_r75367:
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minRev = 75367;
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maxRev = 75367;
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return true;
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case ConfuserVersion.v18_r75369:
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minRev = 75369;
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maxRev = int.MaxValue;
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return true;
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default: throw new ApplicationException("Invalid version");
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}
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}
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}
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}
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