89 lines
2.4 KiB
C#
89 lines
2.4 KiB
C#
/*
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Copyright (C) 2011-2015 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.IO;
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using dnlib.IO;
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namespace de4dot.code.deobfuscators.CodeVeil {
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class ErexResourceReader {
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IBinaryReader reader;
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uint[] key;
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public ErexResourceReader(IBinaryReader reader) {
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this.reader = reader;
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}
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public byte[] Decrypt() {
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if (reader.ReadUInt32() != 0x58455245)
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throw new InvalidDataException("Invalid EREX sig");
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if (reader.ReadInt32() > 1)
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throw new ApplicationException("Invalid EREX file");
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byte flags = reader.ReadByte();
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bool isEncrypted = (flags & 1) != 0;
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bool isDeflated = (flags & 2) != 0;
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int length = reader.ReadInt32();
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if (length < 0)
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throw new ApplicationException("Invalid length");
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if (isEncrypted)
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ReadKey();
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if (isDeflated)
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reader = Inflate(length);
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if (isEncrypted)
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reader = Decrypt(length);
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return reader.ReadBytes(length);
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}
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void ReadKey() {
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key = new uint[reader.ReadByte()];
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for (int i = 0; i < key.Length; i++)
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key[i] = reader.ReadUInt32();
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}
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IBinaryReader Inflate(int length) {
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var data = reader.ReadRemainingBytes();
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return MemoryImageStream.Create(DeobUtils.Inflate(data, true));
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}
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IBinaryReader Decrypt(int length) {
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var block = new uint[4];
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var decrypted = new byte[16];
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var outStream = new MemoryStream(length);
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while (reader.Position < reader.Length) {
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block[0] = reader.ReadUInt32();
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block[1] = reader.ReadUInt32();
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block[2] = reader.ReadUInt32();
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block[3] = reader.ReadUInt32();
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DeobUtils.XxteaDecrypt(block, key);
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Buffer.BlockCopy(block, 0, decrypted, 0, decrypted.Length);
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outStream.Write(decrypted, 0, decrypted.Length);
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}
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return MemoryImageStream.Create(outStream.ToArray());
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}
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}
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}
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