/*
Copyright (C) 2011-2014 de4dot@gmail.com
This file is part of de4dot.
de4dot is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
de4dot is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with de4dot. If not, see .
*/
using System;
using System.Collections.Generic;
using System.IO;
using dnlib.IO;
using dnlib.DotNet;
namespace de4dot.code.deobfuscators.ILProtector {
class StaticMethodsDecrypter : MethodsDecrypterBase {
IDecrypter decrypter;
interface IDecrypter {
string Version { get; }
byte[] GetMethodsData(EmbeddedResource resource);
}
class DecrypterBase : IDecrypter {
protected static readonly byte[] ilpPublicKeyToken = new byte[8] { 0x20, 0x12, 0xD3, 0xC0, 0x55, 0x1F, 0xE0, 0x3D };
protected string ilpVersion;
protected int startOffset;
protected byte[] decryptionKey;
protected int decryptionKeyMod;
public string Version {
get { return ilpVersion; }
}
protected void SetVersion(Version version) {
if (version.Revision == 0)
ilpVersion = string.Format("{0}.{1}.{2}", version.Major, version.Minor, version.Build);
else
ilpVersion = version.ToString();
}
public virtual byte[] GetMethodsData(EmbeddedResource resource) {
var reader = resource.Data;
reader.Position = startOffset;
if ((reader.ReadInt32() & 1) != 0)
return Decompress(reader);
else
return reader.ReadRemainingBytes();
}
byte[] Decompress(IBinaryReader reader) {
return Decompress(reader, decryptionKey, decryptionKeyMod);
}
static void Copy(byte[] src, int srcIndex, byte[] dst, int dstIndex, int size) {
for (int i = 0; i < size; i++)
dst[dstIndex++] = src[srcIndex++];
}
static byte[] Decompress(IBinaryReader reader, byte[] key, int keyMod) {
return Decompress(new byte[reader.Read7BitEncodedUInt32()], reader, key, keyMod);
}
protected static byte[] Decompress(byte[] decrypted, IBinaryReader reader, byte[] key, int keyMod) {
int destIndex = 0;
while (reader.Position < reader.Length) {
if (destIndex >= decrypted.Length)
break;
byte flags = reader.ReadByte();
for (int mask = 1; mask != 0x100; mask <<= 1) {
if (reader.Position >= reader.Length)
break;
if (destIndex >= decrypted.Length)
break;
if ((flags & mask) != 0) {
int displ = (int)reader.Read7BitEncodedUInt32();
int size = (int)reader.Read7BitEncodedUInt32();
Copy(decrypted, destIndex - displ, decrypted, destIndex, size);
destIndex += size;
}
else {
byte b = reader.ReadByte();
if (key != null)
b ^= key[destIndex % keyMod];
decrypted[destIndex++] = b;
}
}
}
return decrypted;
}
}
// 1.0.0 - 1.0.4
class DecrypterV100 : DecrypterBase {
// This is the first four bytes of ILProtector's public key token
const uint RESOURCE_MAGIC = 0xC0D31220;
DecrypterV100(Version ilpVersion) {
SetVersion(ilpVersion);
this.startOffset = 8;
this.decryptionKey = ilpPublicKeyToken;
this.decryptionKeyMod = 8;
}
public static DecrypterV100 Create(IBinaryReader reader) {
reader.Position = 0;
if (reader.Length < 12)
return null;
if (reader.ReadUInt32() != RESOURCE_MAGIC)
return null;
return new DecrypterV100(new Version(reader.ReadByte(), reader.ReadByte(), reader.ReadByte(), reader.ReadByte()));
}
}
// 1.0.5
class DecrypterV105 : DecrypterBase {
DecrypterV105(Version ilpVersion, byte[] key) {
SetVersion(ilpVersion);
this.startOffset = 0xA0;
this.decryptionKey = key;
this.decryptionKeyMod = key.Length - 1;
}
public static DecrypterV105 Create(IBinaryReader reader) {
reader.Position = 0;
if (reader.Length < 0xA4)
return null;
var key = reader.ReadBytes(0x94);
if (!Utils.Compare(reader.ReadBytes(8), ilpPublicKeyToken))
return null;
return new DecrypterV105(new Version(reader.ReadByte(), reader.ReadByte(), reader.ReadByte(), reader.ReadByte()), key);
}
}
// 1.0.6.x
class DecrypterV106 : DecrypterBase {
byte[] decryptionKey6;
byte[] decryptionKey7;
DecrypterV106(byte[] key0, byte[] key6, byte[] key7, int startOffset) {
this.ilpVersion = "1.0.6.x";
this.startOffset = startOffset;
this.decryptionKey = key0;
this.decryptionKey6 = key6;
this.decryptionKey7 = key7;
this.decryptionKeyMod = key0.Length - 1;
}
public static DecrypterV106 Create(IBinaryReader reader) {
try {
int keyXorOffs7 = (ReadByteAt(reader, 0) ^ ReadByteAt(reader, 2)) + 2;
reader.Position = keyXorOffs7 + (ReadByteAt(reader, 1) ^ ReadByteAt(reader, keyXorOffs7));
int sha1DataLen = reader.Read7BitEncodedInt32() + 0x80;
int keyXorOffs6 = (int)reader.Position;
int encryptedOffs = (int)reader.Position + sha1DataLen;
var sha1Data = reader.ReadBytes(sha1DataLen);
uint crc32 = CRC32.CheckSum(sha1Data);
reader.Position = reader.Length - 0x18;
uint origCrc32 = reader.ReadUInt32();
if (crc32 != origCrc32)
return null;
var key0 = DeobUtils.Sha1Sum(sha1Data); // 1.0.6.0
var key6 = GetKey(reader, key0, keyXorOffs6); // 1.0.6.6
var key7 = GetKey(reader, key0, keyXorOffs7); // 1.0.6.7
return new DecrypterV106(key0, key6, key7, encryptedOffs);
}
catch (IOException) {
return null;
}
}
static byte[] GetKey(IBinaryReader reader, byte[] sha1Sum, int offs) {
var key = (byte[])sha1Sum.Clone();
reader.Position = offs;
for (int i = 0; i < key.Length; i++)
key[i] ^= reader.ReadByte();
return key;
}
static byte ReadByteAt(IBinaryReader reader, int offs) {
reader.Position = offs;
return reader.ReadByte();
}
public override byte[] GetMethodsData(EmbeddedResource resource) {
var reader = resource.Data;
reader.Position = startOffset;
var decrypted = new byte[reader.Read7BitEncodedUInt32()];
uint origCrc32 = reader.ReadUInt32();
long pos = reader.Position;
var keys = new byte[][] { decryptionKey, decryptionKey6, decryptionKey7 };
foreach (var key in keys) {
try {
reader.Position = pos;
Decompress(decrypted, reader, key, decryptionKeyMod);
uint crc32 = CRC32.CheckSum(decrypted);
if (crc32 == origCrc32)
return decrypted;
}
catch (OutOfMemoryException) {
}
catch (IOException) {
}
}
throw new ApplicationException("Could not decrypt methods data");
}
}
public string Version {
get { return decrypter == null ? null : decrypter.Version; }
}
public bool Detected {
get { return methodsResource != null; }
}
public StaticMethodsDecrypter(ModuleDefMD module, MainType mainType)
: base(module, mainType) {
}
public void Find() {
foreach (var tmp in module.Resources) {
var resource = tmp as EmbeddedResource;
if (resource == null)
continue;
var reader = resource.Data;
reader.Position = 0;
if (!CheckResourceV100(reader) &&
!CheckResourceV105(reader) &&
!CheckResourceV106(reader))
continue;
methodsResource = resource;
break;
}
}
bool CheckResourceV100(IBinaryReader reader) {
decrypter = DecrypterV100.Create(reader);
return decrypter != null;
}
bool CheckResourceV105(IBinaryReader reader) {
decrypter = DecrypterV105.Create(reader);
return decrypter != null;
}
bool CheckResourceV106(IBinaryReader reader) {
decrypter = DecrypterV106.Create(reader);
return decrypter != null;
}
protected override void DecryptInternal() {
if (methodsResource == null || decrypter == null)
return;
foreach (var info in ReadMethodInfos(decrypter.GetMethodsData(methodsResource)))
methodInfos[info.id] = info;
}
static DecryptedMethodInfo[] ReadMethodInfos(byte[] data) {
var toOffset = new Dictionary();
var reader = MemoryImageStream.Create(data);
int numMethods = (int)reader.Read7BitEncodedUInt32();
int totalCodeSize = (int)reader.Read7BitEncodedUInt32();
var methodInfos = new DecryptedMethodInfo[numMethods];
int offset = 0;
for (int i = 0; i < numMethods; i++) {
int id = (int)reader.Read7BitEncodedUInt32();
int size = (int)reader.Read7BitEncodedUInt32();
var info = new DecryptedMethodInfo(id, size);
methodInfos[i] = info;
toOffset[info] = offset;
offset += size;
}
long dataOffset = reader.Position;
foreach (var info in methodInfos) {
reader.Position = dataOffset + toOffset[info];
reader.Read(info.data, 0, info.data.Length);
}
return methodInfos;
}
}
}