Added WIP decryption support

DecimaExplorer.vcxproj

@@ -22,32 +22,32 @@
     <VCProjectVersion>15.0</VCProjectVersion>
     <ProjectGuid>{05B0E20F-1ED1-4EA1-B3BF-9FDFDD7E26B3}</ProjectGuid>
     <RootNamespace>DecimaExplorer</RootNamespace>
-    <WindowsTargetPlatformVersion>10.0.16299.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
@@ -117,18 +117,24 @@
   <ItemGroup>
     <ClCompile Include="archive\DecimaArchive.cpp" />
     <ClCompile Include="cli\CLI.cpp" />
+    <ClCompile Include="hash\md5.c" />
+    <ClCompile Include="hash\MurmurHash3.cpp" />
     <ClCompile Include="main.cpp" />
     <ClCompile Include="ooz\Kraken.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="archive\DecimaArchive.h" />
     <ClInclude Include="archive\DecimaArchiveError.h" />
     <ClInclude Include="cli\CLI.h" />
+    <ClInclude Include="hash\md5.h" />
+    <ClInclude Include="hash\MurmurHash3.h" />
     <ClInclude Include="ooz\Kraken.h" />
     <ClInclude Include="ooz\targetver.h" />
   </ItemGroup>
   <ItemGroup>
+    <None Include="LICENSE.md" />
     <None Include="ooz\LICENSE.md" />
+    <None Include="README.md" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">

DecimaExplorer.vcxproj.filters

@@ -27,6 +27,12 @@
     <ClCompile Include="cli\CLI.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="hash\MurmurHash3.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="hash\md5.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="ooz\Kraken.h">
@@ -44,8 +50,16 @@
     <ClInclude Include="cli\CLI.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="hash\MurmurHash3.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="hash\md5.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="ooz\LICENSE.md" />
+    <None Include="LICENSE.md" />
+    <None Include="README.md" />
   </ItemGroup>
 </Project>

DecimaExplorer.vcxproj.user

@@ -7,4 +7,8 @@
     <LocalDebuggerCommandArguments>-e Initial.bin 0 c:\test.bin</LocalDebuggerCommandArguments>
     <DebuggerFlavor>WindowsLocalDebugger</DebuggerFlavor>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <LocalDebuggerCommandArguments>-e 7017f9bb9d52fc1c4433599203cc51b1.bin 0 0out.bin</LocalDebuggerCommandArguments>
+    <DebuggerFlavor>WindowsLocalDebugger</DebuggerFlavor>
+  </PropertyGroup>
 </Project>

README.md

@@ -2,16 +2,20 @@
 # Decima Explorer
 
 
-Decima Explorer is a free and open-source program designed to allow you to unpack files from the archive structure used by games using the Decima engine. Currently files must be extracted using their ID as I am unaware of how the file names are mapped. I suspect a hashing algorithm is used for lookup but am unsure of which one.
+Decima Explorer is a free and open-source program designed to allow you to unpack files from the archive structure used by games using the Decima engine. Currently files must be extracted using their ID as I am unaware of how the file names are mapped.
+
+Early work-in-progress support for encrypted files has been added thanks to Ekey, and [Wunkolo](https://github.com/Wunkolo) for researching, implementing and documenting the decryption algorithm. Wunkolo's [implementation can be found here](https://github.com/Wunkolo). 
 
 This program uses [Ooz](https://github.com/powzix/ooz) created by [Powzix](https://github.com/powzix) for decompression. It is slightly modified for this programs purposes. Ooz is under GPL licensing.
 
+This program also uses [Murmur3](https://github.com/PeterScott/murmur3) by [Peter Scott](https://github.com/PeterScott/murmur3).
+
 If anyone has any issue with this project's existence please feel free to reach out to me.
 
 ### To Do
  - Create GUI variant
  - Implement Repack command
- - Understand how the file strings match to files
+ - Understand how the file strings match to files (Appears to be Murmur3Hash but not seeing expected results)
 
 ##  Usage
 

archive/DecimaArchive.cpp

@@ -2,7 +2,11 @@
 #include "DecimaArchiveError.h"
 
 bool DecimaArchive::checkMagic() {
-	return header.magic == 0x20304050;
+	return (header.magic == 0x20304050) || (header.magic == 0x21304050);
+}
+
+bool DecimaArchive::isEncrypted() {
+	return header.magic == 0x21304050;
 }
 
 std::string DecimaArchive::getFilename() {
@@ -18,7 +22,7 @@ DecimaArchive::DecimaArchive(std::string filename) {
 }
 
 int DecimaArchive::getVersion() {
-	return header.version;
+	return header.key;
 }
 
 DecimaArchive::~DecimaArchive() {
@@ -38,7 +42,7 @@ int DecimaArchive::calculateChunkTableOffset(uint64_t fileTableCount) {
 
 void DecimaArchive::parseHeader(FILE* f) {
 	fread(&header.magic, 4, 1, f);
-	fread(&header.version, 4, 1, f);
+	fread(&header.key, 4, 1, f);
 	fread(&header.fileSize, 8, 1, f);
 	fread(&header.dataSize, 8, 1, f);
 	fread(&header.fileTableCount, 8, 1, f);
@@ -51,11 +55,11 @@ void DecimaArchive::parseFileTable(FILE* f, uint64_t fileTableCount) {
 		DecimaFileEntry fileEntry;
 
 		fread(&fileEntry.entryNum, 4, 1, f);
-		fread(&fileEntry.unknown, 4, 1, f);
-		fread(&fileEntry.unknown2, 8, 1, f);
+		fread(&fileEntry.key, 4, 1, f);
+		fread(&fileEntry.hash, 8, 1, f);
 		fread(&fileEntry.offset, 8, 1, f);
 		fread(&fileEntry.size, 4, 1, f);
-		fread(&fileEntry.unknown3, 4, 1, f);
+		fread(&fileEntry.key2, 4, 1, f);
 
 		fileTable.push_back(fileEntry);
 	}
@@ -68,10 +72,10 @@ void DecimaArchive::parseChunkTable(FILE* f, uint64_t chunkTableCount) {
 
 		fread(&chunkEntry.uncompressedOffset, 8, 1, f);
 		fread(&chunkEntry.uncompressedSize, 4, 1, f);
-		fread(&chunkEntry.unknown, 4, 1, f);
+		fread(&chunkEntry.key, 4, 1, f);
 		fread(&chunkEntry.compressedOffset, 8, 1, f);
 		fread(&chunkEntry.compressedSize, 4, 1, f);
-		fread(&chunkEntry.unknown2, 4, 1, f);
+		fread(&chunkEntry.key2, 4, 1, f);
 
 		chunkTable.push_back(chunkEntry);
 	}
@@ -146,7 +150,9 @@ DataBuffer DecimaArchive::extract(DecimaFileEntry fileEntry) {
 	DataBuffer tempBuffer(maxNeededSize);
 
 	for (int i = firstChunkRow; i <= lastChunkRow; i++) {
-		decompressChunkData(getChunkData(chunkTable[i]), chunkTable[i].uncompressedSize, &tempBuffer[pos]);
+		DataBuffer chunkData = getChunkData(chunkTable[i]);
+		if (isEncrypted()) decryptChunkData(i, &chunkData);
+		decompressChunkData(chunkData, chunkTable[i].uncompressedSize, &tempBuffer[pos]);
 		pos += chunkTable[i].uncompressedSize;
 	}
 
@@ -160,6 +166,61 @@ DataBuffer DecimaArchive::extract(DecimaFileEntry fileEntry) {
 
 }
 
+void DecimaArchive::decryptHeader() {
+	uint32_t* p = (uint32_t*)&header + 2;
+	cipher(header.key, header.key + 1, p);
+}
+
+void DecimaArchive::decryptFileTable() {
+	for (int i = 0; i< header.fileTableCount; i++) {
+		uint32_t* p = (uint32_t*)&fileTable[i];
+		cipher(fileTable[i].key, fileTable[i].key2, p);
+	}
+}
+
+void DecimaArchive::decryptChunkTable() {
+	for (int i = 0; i < header.chunkTableCount; i++) {
+		uint32_t* p = (uint32_t*)&chunkTable[i];
+		uint32_t saveKey = chunkTable[i].key;
+		cipher(chunkTable[i].key, chunkTable[i].key2, p);
+		chunkTable[i].key = saveKey;
+	}
+}
+
+void DecimaArchive::decryptChunkData(int32_t id, DataBuffer* data) {
+	dataCipher(id, &(*data)[0], data->size());
+}
+
+void DecimaArchive::cipher(uint32_t key, uint32_t key2, uint32_t *src) {
+	uint32_t iv[4];
+	uint32_t inputKey[2][4] = {
+								{ key,  murmurSalt[1], murmurSalt[2], murmurSalt[3] }, 
+								{ key2, murmurSalt[1], murmurSalt[2], murmurSalt[3] } 
+	};
+
+	for (int i = 0; i < 2; i++) {
+		MurmurHash3_x64_128(inputKey[i], 0x10, seed, iv);
+		for (int j = 0; j < 4; j++) {
+			src[(i * 4) + j] ^= iv[j];
+		}
+	}
+}
+
+void DecimaArchive::dataCipher(uint32_t chunkID, uint8_t* src, int size) {
+	uint32_t iv[4];
+	MurmurHash3_x64_128(&chunkTable[chunkID].uncompressedOffset, 0x10, seed, iv);
+
+	for (int i = 0; i < 4; i++) {
+		iv[i] ^= murmurSalt2[i];
+	}
+
+	md5_byte_t* digest = md5Hash((md5_byte_t*)iv, 16);
+
+	for (int i = 0; i < size; i++) {
+		src[i] ^= digest[i % 16];
+	}
+}
+
 int DecimaArchive::open() {
 	FILE *f;
 	fopen_s(&f, getFilename().c_str(), "rb");
@@ -176,8 +237,14 @@ int DecimaArchive::open() {
 		return 0;
 	}
 
+	if (isEncrypted()) decryptHeader();
+
 	parseFileTable(f, header.fileTableCount);
+	if (isEncrypted()) decryptFileTable();
+
 	parseChunkTable(f, header.chunkTableCount);
+	if (isEncrypted()) decryptChunkTable();
+
 	fclose(f);
 	return 1;
 }
@@ -193,4 +260,4 @@ int DecimaArchive::extractFile(uint32_t id, std::string output) {
 	DataBuffer data = extract(fileTable[i]);
 	if (!writeDataToFile(data, output)) return 0;
 	return 1;
-}
+}

archive/DecimaArchive.h

@@ -1,12 +1,15 @@
 #pragma once
 
 #include "../ooz/Kraken.h"
+#include "../hash/md5.h"
+#include "../hash/MurmurHash3.h"
+#include <string>
 #include <inttypes.h>
 #include <vector>
 
 typedef struct DecimaHeader {
 	uint32_t magic; //0x20304050
-	uint32_t version; //0x3D
+	uint32_t key;
 	uint64_t fileSize;
 	uint64_t dataSize;
 	uint64_t fileTableCount;
@@ -16,20 +19,20 @@ typedef struct DecimaHeader {
 
 typedef struct DecimaFileEntry {
 	uint32_t entryNum;
-	uint32_t unknown;
-	uint64_t unknown2; //maybe file hash, not sure
+	uint32_t key;
+	uint64_t hash;
 	uint64_t offset;
 	uint32_t size;
-	uint32_t unknown3;
+	uint32_t key2;
 } DecimaFileTable;
 
 typedef struct DecimaChunkEntry {
 	uint64_t uncompressedOffset; //relative offset once uncompressed
 	uint32_t uncompressedSize;
-	uint32_t unknown;
+	uint32_t key;
 	uint64_t compressedOffset;
 	uint32_t compressedSize;
-	uint32_t unknown2;
+	uint32_t key2;
 } DecimaChunkTable;
 
 typedef std::vector<uint8_t> DataBuffer;
@@ -42,18 +45,29 @@ class DecimaArchive {
 
 	std::string filename;
 
+	uint8_t seed = 0x2A;
+	uint32_t murmurSalt[4]  = { 0x0FA3A9443, 0x0F41CAB62, 0x0F376811C, 0x0D2A89E3E };
+	uint32_t murmurSalt2[4] = { 0x06C084A37, 0x07E159D95, 0x03D5AF7E8, 0x018AA7D3F };
+
 	void parseHeader(FILE* file);
 	void parseFileTable(FILE* f, uint64_t fileTableCount);
 	void parseChunkTable(FILE* f, uint64_t chunkTableCount);
 
 	bool checkMagic();
+	bool isEncrypted();
+	void decryptHeader();
+	void decryptFileTable();
+	void decryptChunkTable();
 	uint32_t getFileEntryIndex(int id);
 	DecimaFileEntry getFileEntry(int id);
 	void setFilename(std::string filename);
 	int findChunkWithOffset(uint64_t offset);
 	DataBuffer extract(DecimaFileEntry fileEntry);
+	void decryptChunkData(int32_t id, DataBuffer* data);
 	DataBuffer getChunkData(DecimaChunkEntry chunkEntry);
 	int calculateChunkTableOffset(uint64_t fileTableCount);
+	void cipher(uint32_t key, uint32_t key2, uint32_t* src);
+	void dataCipher(uint32_t chunkID, uint8_t* src, int size);
 	int writeDataToFile(DataBuffer data, std::string filename);
 	uint64_t calculateFirstContainingChunk(uint64_t fileOffset, int chunkSize);
 	uint64_t calculateLastContainingChunk(uint64_t fileOffset, int fileSize, int chunkSize);