290 lines
7.2 KiB
C#
290 lines
7.2 KiB
C#
/*
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Copyright (C) 2011-2013 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.Collections.Generic;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Eazfuscator_NET {
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interface IDynocodeGenerator {
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IEnumerable<int> GetValues(int input);
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}
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// Something added in EF 3.5 which they call Dynocode. The string decrypter can now
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// call some iterator classes that will return some integers that it will use to
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// XOR some key.
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class Dynocode {
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ISimpleDeobfuscator simpleDeobfuscator;
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Dictionary<TypeDef, IDynocodeGenerator> typeToDCGen = new Dictionary<TypeDef, IDynocodeGenerator>();
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class DCGen1 : IDynocodeGenerator {
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public int magic1;
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public int magic2;
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public int magic3;
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public int magic4;
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public int magic5;
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public int magic6;
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public int magic7;
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public IEnumerable<int> GetValues(int input) {
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yield return magic1;
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yield return magic2;
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yield return input ^ magic3;
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yield return magic4;
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yield return magic5;
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yield return magic6;
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yield return input ^ magic7;
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}
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}
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class DCGen2 : IDynocodeGenerator {
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public int magic1;
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public IEnumerable<int> GetValues(int input) {
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int x = 0;
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int y = 1;
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while (true) {
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yield return y;
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if (--input == 0)
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break;
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int tmp = y;
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y = (x + y + input) ^ magic1;
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x = tmp;
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}
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}
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}
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class DCGen3 : IDynocodeGenerator {
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public int magic1;
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public int magic2;
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public DCGen2 dc2;
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public IEnumerable<int> GetValues(int input) {
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int i = 7;
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foreach (var val in dc2.GetValues(input)) {
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int x = val ^ input;
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if ((x % 4) == 0)
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x ^= magic1;
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if ((x % 16) == 0)
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x ^= magic2;
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yield return x;
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if (--i == 0)
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break;
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}
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}
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}
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public IEnumerable<TypeDef> Types {
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get {
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foreach (var type in typeToDCGen.Keys)
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yield return type.DeclaringType;
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}
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}
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public Dynocode(ISimpleDeobfuscator simpleDeobfuscator) {
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this.simpleDeobfuscator = simpleDeobfuscator;
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}
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public IDynocodeGenerator GetDynocodeGenerator(TypeDef type) {
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if (type == null)
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return null;
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var dt = type.DeclaringType;
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if (dt == null)
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return null;
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IDynocodeGenerator dcGen;
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if (typeToDCGen.TryGetValue(type, out dcGen))
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return dcGen;
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if (dt.NestedTypes.Count == 1)
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dcGen = GetDCGen1(type);
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else if (dt.NestedTypes.Count == 2)
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dcGen = GetDCGen3(type);
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typeToDCGen[type] = dcGen;
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return dcGen;
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}
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DCGen1 GetDCGen1(TypeDef type) {
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var method = GetMoveNext(type);
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if (method == null)
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return null;
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simpleDeobfuscator.Deobfuscate(method);
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var swLabels = GetSwitchLabels(method);
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if (swLabels == null || swLabels.Count < 7)
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return null;
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var dcGen = new DCGen1();
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if (!GetMagicDC1(method, swLabels[0], out dcGen.magic1))
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return null;
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if (!GetMagicDC1(method, swLabels[1], out dcGen.magic2))
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return null;
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if (!GetMagicXorDC1(method, swLabels[2], out dcGen.magic3))
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return null;
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if (!GetMagicDC1(method, swLabels[3], out dcGen.magic4))
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return null;
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if (!GetMagicDC1(method, swLabels[4], out dcGen.magic5))
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return null;
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if (!GetMagicDC1(method, swLabels[5], out dcGen.magic6))
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return null;
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if (!GetMagicXorDC1(method, swLabels[6], out dcGen.magic7))
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return null;
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return dcGen;
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}
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static IList<Instruction> GetSwitchLabels(MethodDef method) {
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code != Code.Switch)
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continue;
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return instr.Operand as IList<Instruction>;
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}
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return null;
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}
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static bool GetMagicDC1(MethodDef method, Instruction target, out int magic) {
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magic = 0;
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var instrs = method.Body.Instructions;
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int index = instrs.IndexOf(target);
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if (index < 0)
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return false;
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for (int i = index; i < instrs.Count - 3; i++) {
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var instr = instrs[i];
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if (instr.OpCode.FlowControl != FlowControl.Next)
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return false;
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if (instr.OpCode.Code != Code.Stfld)
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Ldarg_0)
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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].OpCode.Code != Code.Stfld)
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continue;
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magic = ldci4.GetLdcI4Value();
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return true;
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}
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return false;
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}
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static bool GetMagicXorDC1(MethodDef method, Instruction target, out int magic) {
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magic = 0;
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var instrs = method.Body.Instructions;
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int index = instrs.IndexOf(target);
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if (index < 0)
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return false;
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for (int i = index; i < instrs.Count - 2; i++) {
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var instr = instrs[i];
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if (instr.OpCode.FlowControl != FlowControl.Next)
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return false;
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if (!instr.IsLdcI4())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Xor)
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continue;
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if (instrs[i + 2].OpCode.Code != Code.Stfld)
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continue;
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magic = instr.GetLdcI4Value();
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return true;
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}
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return false;
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}
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DCGen3 GetDCGen3(TypeDef type) {
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var method = GetMoveNext(type);
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if (method == null)
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return null;
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simpleDeobfuscator.Deobfuscate(method);
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var dcGen = new DCGen3();
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int index = 0;
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if (!GetMagicDC3(method, ref index, out dcGen.magic1))
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return null;
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if (!GetMagicDC3(method, ref index, out dcGen.magic2))
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return null;
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var dt = type.DeclaringType;
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dcGen.dc2 = GetDCGen2(dt.NestedTypes[0] == type ? dt.NestedTypes[1] : dt.NestedTypes[0]);
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return dcGen;
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}
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static bool GetMagicDC3(MethodDef method, ref int index, out int magic) {
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var instrs = method.Body.Instructions;
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for (int i = index; i < instrs.Count - 2; i++) {
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var ldci4 = instrs[i];
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if (!ldci4.IsLdcI4())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Xor)
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continue;
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if (instrs[i + 2].OpCode.Code != Code.Stfld)
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continue;
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index = i + 3;
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magic = ldci4.GetLdcI4Value();
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return true;
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}
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magic = 0;
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return false;
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}
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DCGen2 GetDCGen2(TypeDef type) {
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var method = GetMoveNext(type);
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if (method == null)
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return null;
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simpleDeobfuscator.Deobfuscate(method);
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var dcGen = new DCGen2();
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int index = 0;
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if (!GetMagicDC3(method, ref index, out dcGen.magic1))
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return null;
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return dcGen;
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}
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static MethodDef GetMoveNext(TypeDef type) {
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foreach (var m in type.Methods) {
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if (!m.IsVirtual)
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continue;
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foreach (var mo in m.Overrides) {
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if (mo.MethodDeclaration.FullName == "System.Boolean System.Collections.IEnumerator::MoveNext()")
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return m;
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}
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}
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foreach (var m in type.Methods) {
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if (!m.IsVirtual)
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continue;
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if (m.Name != "MoveNext")
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continue;
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if (!DotNetUtils.IsMethod(m, "System.Boolean", "()"))
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continue;
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return m;
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}
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return null;
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}
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}
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}
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