STFS
STFS (Secure Transacted File System) is the file system used by the Xbox 360 for all packages created and downloaded by the system. It is protected using a series of SHA1 hashes and a RSA signature. STFS is commonly found in Xbox 360 Content Packages (XContent), but is not limited to those only as the PEC (Profile Embedded Content) files employ STFS. The two known categories for STFS are read-only and writeable. Read-only content packages are found with a PIRS/LIVE signed header and writeable content packages are console signed (CON).
STFS
The 360 uses packages to transfer saves/content/games/pictures and more. Most packages start with the strings PIRS, LIVE or "CON ", some are even embedded inside gamer profiles (using the PEC format described below). All of these are STFS content packages which hold the real files along with metadata that the dashboard reads like the title, the licenses and the RSA signature which is used to verify the package.
The acronym STFS stands for Secure Transacted File System, which shows how the packages are secure (signature and hashes) and transacted (multiple file / directory revisions)
LIVE and PIRS files come from Xbox Live, these are signed using a private key that only Microsoft has. The console uses a public key which is hardcoded inside it to verify the package and make sure the person is allowed to use it. CON files are created by the console for saves and profiles. The console uses its own private key to sign CON files. Many editors are available for saves and profiles which can be used with no modification to the console.
Throughout an STFS package, there is a series of SHA1 hashes used to verify the package, and help with downloads (if a block isn't valid, it can be redownloaded). The hashes are located at certain parts of the file, a way of calculating where is (will be!) down below.
Volume Descriptor
There are 2 types of volume descriptor a content file may have, one for STFS packages and another for SVOD
STFS
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x00 | 0x01 | byte | Volume descriptor size (0x24) |
| 0x01 | 0x01 | byte | Reserved |
| 0x02 | 0x01 | byte | Block Seperation |
| 0x03 | 0x02 | signed short | File Table Block Count |
| 0x05 | 0x03 | signed int24 | File Table Block Number |
| 0x08 | 0x14 | byte[] | Top Hash Table Hash |
| 0x1C | 0x04 | signed int | Total Allocated Block Count |
| 0x20 | 0x04 | signed int | Total Unallocated Block Count |
SVOD
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x00 | 0x01 | byte | Volume descriptor size (0x24) |
| 0x01 | 0x01 | byte | Block Cache Element Count |
| 0x02 | 0x01 | byte | Worker Thread Processor |
| 0x03 | 0x01 | byte | Worker Thread Priority |
| 0x04 | 0x14 | byte[] | Hash |
| 0x18 | 0x01 | byte | Device features |
| 0x19 | 0x03 | uint24 | Data block count |
| 0x1C | 0x03 | uint24 | Data block offset |
| 0x1F | 0x05 | byte[] | Padding/reserved |
Content Packages
Header
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x4 | ascii string | Magic |
The magic can be one of the following:
| Signature Type | Information |
|---|---|
| "CON " | Signed by a console. Found on many files such as cache files, profiles, saved games. |
| PIRS | Signed by Microsoft. Found on files delivered by Microsoft through non-Xbox Live means such as system updates. |
| LIVE | Signed by Microsoft. Found on files delivered over Xbox Live such as items from the Marketplace like themes. |
The following is used for Console Signed ("CON ") packages, and is used by the Xbox as the format for signatures generated by it:
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x4 | 0x2 | bytes | Public Key Certificate Size |
| 0x6 | 0x5 | bytes | Certificate Owner Console ID |
| 0xB | 0x14 | ascii string | Certificate Owner Console Part Number |
| 0x1F | 0x1 | byte | Certificate Owner Console Type (1 for devkit, 2 for retail) |
| 0x20 | 0x8 | ascii string | Certificate Date of Generation |
| 0x28 | 0x4 | bytes | Public Exponent |
| 0x2C | 0x80 | bytes | Public Modulus |
| 0xAC | 0x100 | bytes | Certificate Signature |
| 0x1AC | 0x80 | bytes | Signature |
and for remotely signed (LIVE/PIRS) packages:
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x4 | 0x100 | bytes | Package Signature |
| 0x104 | 0x128 | bytes | Padding |
The Package Signature is generated using the value at 0x32C (Content ID/Header SHA1).
Metadata
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x22C | 0x100 | license entries (see below) | Licensing Data (used to check package owner) |
| 0x32C | 0x14 | bytes | Header SHA1 Hash (from 0x344 to first hash table) |
| 0x340 | 0x4 | unsigned int | HeaderSize |
| 0x344 | 0x4 | signed int | Content Type (see below) |
| 0x348 | 0x4 | signed int | Metadata Version (see below) |
| 0x34C | 0x8 | signed long | Content Size |
| 0x354 | 0x4 | unsigned int | Media ID |
| 0x358 | 0x4 | signed int | Version (system/title updates) |
| 0x35C | 0x4 | signed int | Base Version (system/title updates) |
| 0x360 | 0x4 | unsigned int | Title ID |
| 0x364 | 0x1 | byte | Platform (Xbox 360 = 2/PC = 4) |
| 0x365 | 0x1 | byte | Executable Type |
| 0x366 | 0x1 | byte | Disc Number |
| 0x367 | 0x1 | byte | Disc In Set |
| 0x368 | 0x4 | unsigned int | Save Game ID |
| 0x36C | 0x5 | bytes | Console ID |
| 0x371 | 0x8 | bytes | Profile ID |
| 0x379 | 0x24 | Volume Descriptor | File System Volume Descriptor |
| 0x39D | 0x4 | signed int | Data File Count |
| 0x3A1 | 0x8 | signed long | Data File Combined Size |
| 937 | 4 | int32(STFS = 0, SVOD = 1) | Descriptor type |
| 941 | 4 | int32 | Reserved |
| 0x3B1 | 0x4C | bytes | Padding |
| 0x3FD | 0x14 | bytes | Device ID |
| 0x411 | 0x900 (each 0x80 = different locale) | unicode string | Display Name |
| 0xD11 | 0x900 (each 0x80 = different locale) | unicode string | Display Description |
| 0x1611 | 0x80 | unicode string | Publisher Name |
| 0x1691 | 0x80 | unicode string | Title Name |
| 0x1711 | 0x1 | byte | Transfer Flags (see below) |
| 0x1712 | 0x4 | signed int | Thumbnail Image Size |
| 0x1716 | 0x4 | signed int | Title Thumbnail Image Size |
| 0x171A | 0x4000 (thumbnail size) | image | Thumbnail Image |
| 0x571A | 0x4000 (title thumbnail size) | image | Title Thumbnail Image |
Version 2
If the Metadata Version field is set to 2, the format is slightly changed:
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x3B1 | 0x10 | bytes | Series ID |
| 0x3C1 | 0x10 | bytes | Season ID |
| 0x3D1 | 0x2 | signed short | Season Number |
| 0x3D5 | 0x2 | signed short | Episode Number |
| 0x3D5 | 0x28 | bytes | Padding |
| 0x171A | 0x3D00 (thumbnail size) | image | Thumbnail Image |
| 0x541A | 0x300 (each 0x80 = different locale) | image | Additional Display Names |
| 0x571A | 0x3D00 (title thumbnail size) | image | Title Thumbnail Image |
| 0x941A | 0x300 (each 0x80 = different locale) | image | Additional Display Descriptions |
License Entries
For every entry in the license data field:
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x8 | signed long | License ID (XUID / PUID / console id) |
| 0x8 | 0x4 | signed int | License Bits |
| 0xC | 0x4 | signed int | License Flags |
Content Types
| Value | Description |
|---|---|
| 0xD0000 | Arcade Title |
| 0x9000 | Avatar Item |
| 0x40000 | Cache File |
| 0x2000000 | Community Game |
| 0x80000 | Game Demo |
| 0x20000 | Gamer Picture |
| 0xA0000 | Game Title |
| 0xC0000 | Game Trailer |
| 0x400000 | Game Video |
| 0x4000 | Installed Game |
| 0xB0000 | Installer |
| 0x2000 | IPTV Pause Buffer |
| 0xF0000 | License Store |
| 0x2 | Marketplace Content |
| 0x100000 | Movie |
| 0x300000 | Music Video |
| 0x500000 | Podcast Video |
| 0x10000 | Profile |
| 0x3 | Publisher |
| 0x1 | Saved Game |
| 0x50000 | Storage Download |
| 0x30000 | Theme |
| 0x200000 | TV |
| 0x90000 | Video |
| 0x600000 | Viral Video |
| 0x70000 | Xbox Download |
| 0x5000 | Xbox Original Game |
| 0x60000 | Xbox Saved Game |
| 0x1000 | Xbox 360 Title |
| 0x5000 | Xbox Title |
| 0xE0000 | XNA |
Transfer Flags
| Value | Description |
|---|---|
| 0x00 | DeviceID and ProfileID Transfer |
| 0x20 | Move Only Transfer |
| 0x40 | DeviceID Transfer |
| 0x80 | ProfileID Transfer |
| 0xC0 | None |
These are bit flags, dunno why everyone treats like enum.
Bit0: None(Yet?)
Bit1: None
Bit2: Deep Link Supported
Bit3: Disable Network Storage
Bit4: Kinect Enabled
Bit5: Move Only Transfer
Bit6: Device Transfer
Bit7: Profile Transfer
Profile Embedded Content (PEC)
When extra security is needed for content which is already using STFS, PEC files may be used to add an extra layer on top. PEC files use the STFS descriptor and algorithms, but has no similarity with content packages.
PEC files are only currently used for avatar items/clothing.
Block 0 starts at 0x3000, and hash table 0 at 0x1000/0x2000.
Header
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x228 | Console Security Certificate | Signed |
| 0x228 | 0x14 | bytes | SHA1 hash from 0x23C-0x1000 |
| 0x23C | 0x8 | signed long | Unknown |
| 0x244 | 0x24 | Volume Descriptor (STFS) | File System Volume Descriptor |
| 0x268 | 0x4 | signed int | Unknown |
| 0x26C | 0x8 | bytes | Profile ID |
| 0x274 | 0x1 | byte | Unknown |
| 0x275 | 0x5 | bytes | Console ID |
File Listing
The value at 0x37E (File Table Block Number on the structure above) determines where the file table begins. As it is a block number, you will have to convert it to an offset. Here is some code in C# for converting:
internal int BlockToOffset(int xBlock)
{
int xReturn = 0;
if (xBlock > 0xFFFFFF)
xReturn = -1;
else
xReturn = (((MetaData.HeaderSize + 0xFFF) & 0xF000) + (xBlock << 12));
return xReturn;
}
internal int ComputeDataBlockNumber(int xBlock)
{
int xBlockShift;
if(((MetaData.HeaderSize + 0xFFF) & 0xF000) == 0xB000)
xBlockShift = 1;
else
if((MetaData.Descriptor.BlockSeperation & 1) == 1)
xBlockShift = 0;
else
xBlockShift = 1;
int xBase = ((xBlock + 0xAA) / 0xAA);
if(this.Header.Magic == XContent_Header.Header_Magic.CON)
xBase = (xBase << xBlockShift);
int xReturn = (xBase + xBlock);
if (xBlock > 0xAA)
{
xBase = ((xBlock + 0x70E4) / 0x70E4);
if (this.Header.Magic == XContent_Header.Header_Magic.CON)
xBase = (xBase << xBlockShift);
xReturn += xBase;
if (xBlock > 0x70E4)
{
xBase = ((xBlock + 0x4AF768) / 0x4AF768);
if (this.Header.Magic == xBlockShift)
xBase = (xBase << 1);
xReturn = (xReturn + xBase);
}
}
return xReturn;
}
Each embedded file starts at a 4096 byte boundary. The optional space between embedded files is filled with null bytes.
The file listing consists of entries which have the format below. The listing ends with an entry consisting of only null bytes.
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x28 | ascii string | File name, null-padded |
| 0x28 | 0x1 | byte | Length of file name, plus flags |
| 0x29 | 0x3 | signed int24 | Number of blocks allocated for file (little endian) |
| 0x2C | 0x3 | signed int24 | Copy of 0x29 |
| 0x2F | 0x3 | signed int24 | Starting block number of file (little endian) |
| 0x32 | 0x2 | signed short | Path indicator (big endian) |
| 0x34 | 0x4 | unsigned int | Size of file in bytes (big endian) |
| 0x38 | 0x4 | signed int | Update date/time stamp of file |
| 0x3C | 0x4 | signed int | Access date/time stamp of file |
Byte 0x28 also has two flags: bit 6 and bit 7. If bit 6 is set it means that all of the blocks in the file are consecutive. Bit 7 indicates that the file is a directory.
The first 6 bits 0-5, are the length of the filename.
public System.Boolean IsDirectory//bit 7
{
get
{
return (Flags & 128) == 128;
}
set
{
if (value != IsDirectory)
{
Flags ^= 128;
}
}
}
//public System.Boolean IsUnknown//bit 6
//{
// get
// {
// return (Flags & 64) == 64;
// }
// set
// {
// if (value != IsUnknown)
// {
// Flags ^= 64;
// }
// }
//}
public System.Byte NameLength//first 6 bits
{
get
{
return (System.Byte)(Flags & 63);
}
set
{
Flags ^= (System.Byte)(value ^ NameLength);
}
}
The path indicator indicates the path of the file. -1 (0xFFFF) means that the file is in the root directory, any other value V refers to the (sub)directory which is listed as the Vth entry in the listing (counting from 0). Directories can nest.
The FAT format is used for the date/time stamps of the files.
Hash Tables / Block Offsets
A block is 0x1000 (4096) bytes and the first block is located at 0xC000. Every 0xAA (170) blocks there is a block that contains a hash of each block and every 0xAA*0xAA (0x70E4) blocks there is another table (presumably hashing the 0xAA table blocks). This means that when using a block number from a file listing you need to account for the hash tables which are not included in the block numbering system. For example block 171 is actually located where you would expect block 172 to reside ((171 + int(171/170)) * 0x1000 + 0xC000).
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x14 | byte | Hash(SHA1) |
| 0x14 | 0x1 | byte | Status byte |
| 0x15 | 0x3 | Int24 | Next block |
The status byte is very important when injecting files into a package. Here are the meanings of them.
| Value | Meaning |
|---|---|
| 0x00 | Unused Block |
| 0x40 | Free Block (previously used) 0x80 Used Block |
| 0x80 | Used Block |
| 0xC0 | Newly Allocated Block |
Files are not always stored in consecutive blocks, you have to find the corresponding hash table record and read the next block number (similar to cluster maps in FAT).
Here is some C# code for converting a block to it's hash table position(it may not work perfectly!):
internal int ComputeLevelNHashBlockNumber(int xBlock, int xLevel)
{
int xBlockShift;
if (((MetaData.HeaderSize + 0xFFF) & 0xF000) == 0xB000)
xBlockShift = 1;
else
if ((MetaData.Descriptor.BlockSeperation & 1) == 1)
xBlockShift = 0;
else
xBlockShift = 1;
int[] xBlockStep;
if (((MetaData.HeaderSize + 0xFFF) & 0xF000) == 0xB000)
xBlockStep = new[] { 0xAC, 0x723A };
else
if ((MetaData.Descriptor.BlockSeperation & 1) == 1)
xBlockStep = new[] { 0xAB, 0x718F };
else
xBlockStep = new[] { 0xAC, 0x723A };
int xReturn;
int xBase;
int xStep = xBlockStep[1];
if (xLevel == 0)
{
xReturn = (xBlock / 0xAA);
xStep = (xReturn * xBlockStep[0]);
if (xReturn != 0)
{
xReturn = (xBlock / 0x70E4);
xBase = (xReturn + 1);
if (this.Header.Magic == XContent_Header.Header_Magic.CON)
xStep += (xBase << xBlockShift);
else
xStep += xBase;
if (xReturn == 0)
return xStep;
else
{
if (this.Header.Magic == XContent_Header.Header_Magic.CON)
return (xStep + (1 << xBlockShift));
else
return (xStep + 1);
}
}
else
return xStep;
}
else if (xLevel == 1)
{
xReturn = (xBlock / 0x70E4);
xBase = (xReturn * xStep);
if (xReturn != 0)
{
if (this.Header.Magic == XContent_Header.Header_Magic.CON)
return (xBase + (1 << xBlockShift));
else
return (xBase + 1);
}
else
return (xBase + xBlockStep[0]);
}
else if (xLevel == 2)
{
return xStep;
}
else
{
throw new Exception("Level Unknown: " + xLevel.ToString());
return 0xFFFFFF;
}
}
Tools
An (old) tool (Python 2.5 required) to analyze and extract these archive files is available at extract360.py (2008-08-03, 23056 bytes, MD5 = 3aa517c83d01c618927b78d0ca665d02)
wxPirs 1.1 can extract from LIVE/PIRS files fine, but as it doesn't use hash tables properly it doesn't work well with CON files.
A newer tool was released by DJ Shepherd called Le Fluffie, which can create and extract from CON/LIVE/PIRS files (but it has some problems with creation, some prefer to use XLAST)
XLAST inside the Xbox 360 SDK can create LIVE/PIRS packages, but it is illegal to share it.
A new python library py360 can read STFS files