84 lines
2.7 KiB
C#
84 lines
2.7 KiB
C#
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/*
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Copyright (C) 2011 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.Text;
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using Mono.Cecil;
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namespace de4dot.deobfuscators.CliSecure {
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class StringDecrypter {
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ModuleDefinition module;
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TypeDefinition stringDecrypterType;
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MethodDefinition stringDecrypterMethod;
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byte[] stringDecrypterKey;
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public bool Detected {
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get { return stringDecrypterKey != null; }
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}
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public TypeDefinition StringDecrypterType {
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get { return stringDecrypterType; }
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}
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public MethodDefinition StringDecrypterMethod {
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get { return stringDecrypterMethod; }
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}
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public StringDecrypter(ModuleDefinition module, MethodDefinition stringDecrypterMethod) {
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this.module = module;
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this.stringDecrypterMethod = stringDecrypterMethod;
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}
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public StringDecrypter(ModuleDefinition module, StringDecrypter oldOne) {
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this.module = module;
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stringDecrypterType = lookup(oldOne.stringDecrypterType, "Could not find stringDecrypterType");
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stringDecrypterMethod = lookup(oldOne.stringDecrypterMethod, "Could not find stringDecrypterMethod");
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stringDecrypterKey = oldOne.stringDecrypterKey;
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}
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T lookup<T>(T def, string errorMessage) where T : MemberReference {
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return DeobUtils.lookup(module, def, errorMessage);
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}
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public void find() {
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foreach (var type in module.Types) {
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if (type.FullName == "<D234>" || type.FullName == "<ClassD234>") {
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stringDecrypterType = type;
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foreach (var field in type.Fields) {
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if (field.FullName == "<D234> <D234>::345" || field.FullName == "<ClassD234>/D234 <ClassD234>::345") {
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stringDecrypterKey = field.InitialValue;
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break;
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}
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}
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break;
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}
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}
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}
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public string decrypt(string es) {
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if (stringDecrypterKey == null)
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throw new ApplicationException("Trying to decrypt strings when stringDecrypterKey is null (could not find it!)");
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StringBuilder sb = new StringBuilder(es.Length);
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for (int i = 0; i < es.Length; i++)
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sb.Append(Convert.ToChar((int)(es[i] ^ stringDecrypterKey[i % stringDecrypterKey.Length])));
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return sb.ToString();
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}
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}
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}
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