73 lines
2.2 KiB
C#
73 lines
2.2 KiB
C#
/*
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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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namespace de4dot.deobfuscators.SmartAssembly {
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class StringDecrypter {
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int stringOffset;
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byte[] decryptedData;
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public bool CanDecrypt {
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get { return decryptedData != null; }
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}
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public StringDecrypterInfo StringDecrypterInfo { get; private set; }
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public StringDecrypter(StringDecrypterInfo stringDecrypterInfo) {
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StringDecrypterInfo = stringDecrypterInfo;
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if (stringDecrypterInfo != null) {
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if (!stringDecrypterInfo.StringsEncrypted) {
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stringOffset = stringDecrypterInfo.StringOffset;
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decryptedData = stringDecrypterInfo.StringsResource.GetResourceData();
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}
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else if (stringDecrypterInfo.CanDecrypt) {
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stringOffset = stringDecrypterInfo.StringOffset;
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decryptedData = stringDecrypterInfo.decrypt();
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}
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}
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}
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public string decrypt(int token, int id) {
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if (!CanDecrypt)
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throw new ApplicationException("Can't decrypt strings since decryptedData is null");
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int index = id - (token & 0x00FFFFFF) - stringOffset;
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int len;
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byte b = decryptedData[index++];
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if ((b & 0x80) == 0)
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len = b;
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else if ((b & 0x40) == 0)
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len = ((b & 0x3F) << 8) + decryptedData[index++];
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else {
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len = ((b & 0x1F) << 24) +
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((int)decryptedData[index++] << 16) +
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((int)decryptedData[index++] << 8) +
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decryptedData[index++];
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}
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var decodedData = Convert.FromBase64String(Encoding.UTF8.GetString(decryptedData, index, len));
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return Encoding.UTF8.GetString(decodedData, 0, decodedData.Length);
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}
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}
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}
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