Secure Transacted File System (STFS) Support (#78)

* Initial STFS support

* Fix build errors

* Fix more build errors

* Final fix

* Cleanup printer

* Fix indent

SabreTools.Data.Models/STFS/ConsoleSignature.cs

@@ -0,0 +1,64 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// Signature signed by console, for "CON " format STFS files
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class ConsoleSignature : Signature
+    {
+        /// <summary>
+        /// Public Key Certificate Size
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public ushort CertificateSize { get; set; }
+
+        /// <summary>
+        /// Certificate Owner Console ID
+        /// </summary>
+        /// <remarks>5 bytes</remarks>
+        public byte[] ConsoleID { get; set; } = new byte[5];
+
+        /// <summary>
+        /// Certificate Owner Console Part Number
+        /// </summary>
+        /// <remarks>20 bytes, ASCII string</remarks>
+        public byte[] PartNumber { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Certificate Owner Console Type (1 for devkit, 2 for retail)
+        /// </summary>
+        public byte ConsoleType { get; set; }
+
+        /// <summary>
+        /// Certificate Date of Generation
+        /// </summary>
+        /// <remarks>8 bytes, ASCII string</remarks>
+        public byte[] CertificateDate { get; set; } = new byte[8];
+
+        /// <summary>
+        /// Public Exponent
+        /// </summary>
+        /// <remarks>4 bytes</remarks>
+        public byte[] PublicExponent { get; set; } = new byte[4];
+
+        /// <summary>
+        /// Public Modulus
+        /// </summary>
+        /// <remarks>128 bytes</remarks>
+        public byte[] PublicModulus { get; set; } = new byte[128];
+
+        /// <summary>
+        /// Certificate Signature
+        /// </summary>
+        /// <remarks>256 bytes</remarks>
+        public byte[] CertificateSignature { get; set; } = new byte[256];
+
+        /// <summary>
+        /// Signature
+        /// </summary>
+        /// <remarks>128 bytes</remarks>
+        public byte[] Signature { get; set; } = new byte[128];
+    }
+}

SabreTools.Data.Models/STFS/Constants.cs

@@ -0,0 +1,43 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public static class Constants
+    {
+        /// <summary>
+        /// STFS LIVE magic number ("LIVE")
+        /// </summary>
+        public static readonly byte[] MagicBytesLIVE = [0x4C, 0x49, 0x56, 0x45];
+
+        /// <summary>
+        /// STFS LIVE magic string ("LIVE")
+        /// </summary>
+        public const string MagicStringLIVE = "LIVE";
+
+        /// <summary>
+        /// STFS PIRS magic number ("PIRS")
+        /// </summary>
+        public static readonly byte[] MagicBytesPIRS = [0x50, 0x49, 0x52, 0x53];
+
+        /// <summary>
+        /// STFS PIRS magic string ("PIRS")
+        /// </summary>
+        public const string MagicStringPIRS = "PIRS";
+
+        /// <summary>
+        /// STFS CON magic number ("CON ")
+        /// </summary>
+        public static readonly byte[] MagicBytesCON = [0x43, 0x4F, 0x4E, 0x20];
+
+        /// <summary>
+        /// STFS CON magic string ("CON")
+        /// </summary>
+        public const string MagicStringCON = "CON ";
+
+        /// <summary>
+        /// Standard length of an STFS header
+        /// </summary>
+        public const uint StandardHeaderSize = 0xB000;
+    }
+}

SabreTools.Data.Models/STFS/Enums.cs

@@ -0,0 +1,61 @@
+using System;
+
+namespace SabreTools.Data.Models.XenonExecutable
+{
+    /// <summary>
+    /// STFS Volume Content Type possible values
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public enum ContentType : int
+    {
+        SAVED_GAME = 0x00000001,
+        MARKETPLACE_CONTENT = 0x00000002,
+        PUBLISHER = 0x00000003,
+        XBOX_360_TITLE = 0x00001000,
+        IPTV_PAUSE_BUFFER = 0x00002000,
+        INSTALLED_GAME = 0x00004000,
+        XBOX_ORIGINAL_GAME = 0x00005000,
+        XBOX_TITLE = 0x00006000,
+        GAME_ON_DEMAND = 0x00007000,
+        AVATAR_ITEM = 0x00009000,
+        PROFILE = 0x00010000,
+        GAMER_PICTURE = 0x00020000,
+        THEME = 0x00030000,
+        CACHE_FILE = 0x00040000,
+        STORAGE_DOWNLOAD = 0x00050000,
+        XBOX_SAVED_GAME = 0x00060000,
+        XBOX_DOWNLOAD = 0x00070000,
+        GAME_DEMO = 0x00080000,
+        VIDEO = 0x00090000,
+        GAME_TITLE = 0x000A0000,
+        INSTALLER = 0x000B0000,
+        GAME_TRAILER = 0x000C0000,
+        ARCADE_TITLE = 0x000D0000,
+        XNA = 0x000E0000,
+        LICENSE_STORE = 0x000F0000,
+        MOVIE = 0x00100000,
+        TV = 0x00200000,
+        MUSIC_VIDEO = 0x00300000,
+        GAME_VIDEO = 0x00400000,
+        PODCAST_VIDEO = 0x00500000,
+        VIRAL_VIDEO = 0x00600000,
+        COMMUNITY_GAME = 0x02000000,
+    }
+
+    /// <summary>
+    /// STFS Transfer Flags
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    [Flags]
+    public enum TransferFlags : uint
+    {
+        NONE1 = 0x00000001,
+        NONE2 = 0x00000002,
+        DEEP_LINK_SUPPORTED = 0x00000004,
+        DISABLE_NETWORK_STORAGE = 0x00000008,
+        KINECT_ENABLED = 0x00000010,
+        MOVE_ONLY_TRANSFER = 0x00000020,
+        DEVICE_ID_TRANSFER = 0x00000040,
+        PROFILE_ID_TRANSFER = 0x00000080,
+    }
+}

SabreTools.Data.Models/STFS/HashTable.cs

@@ -0,0 +1,16 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Hash Table in a Hash Table Block 
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class HashTable
+    {
+        /// <summary>
+        /// 170 hash table entries in a single table/block
+        /// </summary>
+        public HashTableEntry[] HashTableEntries { get; set; } = new HashTableEntry[170];
+    }
+}

SabreTools.Data.Models/STFS/HashTableEntry.cs

@@ -0,0 +1,33 @@
+using System.Collections.Generic;
+using SabreTools.Numerics;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Hash Table Entry in a Hash Block's Hash Table
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class HashTableEntry
+    {
+        /// <summary>
+        /// SHA-1 hash of the block
+        /// </summary>
+        public byte[] Hash { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Status of the block
+        /// 0x00 = Unused block
+        /// 0x40 = Free block (previously used, now freed)
+        /// 0x80 = Used block
+        /// 0xC0 = Newly allocated block
+        /// </summary>
+        public byte Status { get; set; }
+
+        /// <summary>
+        /// Block number corresponding to the hash
+        /// FFFFFF = Block 1 (starting 0xB000)
+        /// </summary>
+        /// <remarks>Big-endian, 3-byte uint24</remarks>
+        public UInt24 BlockNumber { get; set; } = new();
+    }
+}

SabreTools.Data.Models/STFS/Header.cs

@@ -0,0 +1,280 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// Secure Transacted File System, Header format
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class Header
+    {
+        /// <summary>
+        /// Magic bytes indicating the format
+        /// Possible values are "LIVE", "PIRS, and "CON "
+        /// </summary>
+        /// <remarks>4 bytes</remarks>
+        public byte[] MagicBytes { get; set; } = new byte[4];
+
+        /// <summary>
+        /// Signature Block
+        /// Not optional, but abstract class
+        /// </summary>
+        /// <remarks>552 bytes</remarks>
+        public Signature? Signature { get; set; }
+
+        /// <summary>
+        /// Used to check package owner
+        /// 16 license entries, 16 bytes each
+        /// </summary>
+        /// <remarks>256 bytes</remarks>
+        public LicenseEntry[] LicensingData { get; set; } = new LicenseEntry[16];
+
+        /// <summary>
+        /// SHA-1 Integrity Hash of the header (from ContentType/0x344 to first hash table) 
+        /// </summary>
+        /// <remarks>20 bytes</remarks>
+        public byte[] HeaderHash { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Size of the header, in bytes (from ??? to ???)
+        /// The actual end of header is padded and zeroed up until next multiple of 4096 bytes
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint HeaderSize { get; set; }
+
+        /// <summary>
+        /// Indication of the content in the STFS
+        /// See Enum.ContentType
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int ContentType { get; set; }
+
+        /// <summary>
+        /// Intended meaning of some of the below fields
+        /// Known values are 0, 1 and 2
+        /// 0 = A bunch of fields will be zeroed (Seen in system updates)
+        /// 1 = All but the below fields are set
+        /// 2 = The following new fields are set:
+        /// SeriesID, SeasonID, SeasonNumber, EpisodeNumber,
+        /// AdditionalDisplayNames, AdditionalDisplayDescriptions
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int MetadataVersion { get; set; }
+
+        /// <summary>
+        /// Size of content in bytes
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public long ContentSize { get; set; }
+
+        /// <summary>
+        /// Media ID
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint MediaID { get; set; }
+
+        /// <summary>
+        /// Version of System/Title Updates
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int Version { get; set; }
+
+        /// <summary>
+        /// Base Version of System/Title Updates
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int BaseVersion { get; set; }
+
+        /// <summary>
+        /// Title ID
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint TitleID { get; set; }
+
+        /// <summary>
+        /// Intended platform for content
+        /// 0 = ???, 2 = Xbox 360, 4 = PC
+        /// </summary>
+        public byte Platform { get; set; }
+
+        /// <summary>
+        /// Intended platform for content
+        /// Xbox 360 = 2, PC = 4
+        /// </summary>
+        public byte ExecutableType { get; set; }
+
+        /// <summary>
+        /// Disc Number
+        /// </summary>
+        public byte DiscNumber { get; set; }
+
+        /// <summary>
+        /// Disc In Set
+        /// </summary>
+        public byte DiscInSet { get; set; }
+
+        /// <summary>
+        /// Save Game ID
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint SaveGameID { get; set; }
+
+        /// <summary>
+        /// Console ID
+        /// </summary>
+        /// <remarks>5 bytes</remarks>
+        public byte[] ConsoleID { get; set; } = new byte[5];
+
+        /// <summary>
+        /// Profile ID
+        /// </summary>
+        /// <remarks>8 bytes</remarks>
+        public byte[] ProfileID { get; set; } = new byte[8];
+
+        /// <summary>
+        /// STFS Volume Descriptor
+        /// Not optional, but abstract class
+        /// </summary>
+        public VolumeDescriptor? VolumeDescriptor { get; set; }
+
+        /// <summary>
+        /// Data File Count
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int DataFileCount { get; set; }
+
+        /// <summary>
+        /// Data File Combined Size, in bytes
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public long DataFileCombinedSize { get; set; }
+
+        /// <summary>
+        /// Descriptor Type
+        /// 0 = STFS, 1 = SVOD
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint DescriptorType { get; set; }
+
+        /// <summary>
+        /// Reserved bytes, should be all zeroed
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public uint Reserved { get; set; }
+
+        /// <summary>
+        /// Series ID
+        /// Zeroed for MetadataVersion = 1
+        /// </summary>
+        /// <remarks>16 bytes</remarks>
+        public byte[]? SeriesID { get; set; } = new byte[16];
+
+        /// <summary>
+        /// Season ID
+        /// Zeroed for MetadataVersion = 1
+        /// </summary>
+        /// <remarks>16 bytes</remarks>
+        public byte[]? SeasonID { get; set; } = new byte[16];
+
+        /// <summary>
+        /// Season Number
+        /// Zeroed for MetadataVersion = 1
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public short? SeasonNumber { get; set; }
+
+        /// <summary>
+        /// Season Number
+        /// Zeroed for MetadataVersion = 1
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public short? EpisodeNumber { get; set; }
+
+        /// <summary>
+        /// Padding bytes
+        /// If MetadataVersion is 2, there are 40 bytes
+        /// Otherwise, there are 76 bytes
+        /// </summary>
+        /// <remarks>40 bytes</remarks>
+        public byte[] Padding { get; set; } = [];
+
+        /// <summary>
+        /// Device ID
+        /// </summary>
+        /// <remarks>20 bytes</remarks>
+        public byte[] DeviceID { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Display Name, UTF-8 string
+        /// 128 bytes per locale, 18 different locales
+        /// </summary>
+        /// <remarks>2304 bytes, UTF-8 string</remarks>
+        public byte[] DisplayName { get; set; } = new byte[2304];
+
+        /// <summary>
+        /// Display Description, UTF-8 string
+        /// 128 bytes per locale, 18 different locales
+        /// </summary>
+        /// <remarks>2304 bytes, UTF-8 string</remarks>
+        public byte[] DisplayDescription { get; set; } = new byte[2304];
+
+        /// <summary>
+        /// Publisher Name, UTF-8 string
+        /// </summary>
+        /// <remarks>128 bytes, UTF-8 string</remarks>
+        public byte[] PublisherName { get; set; } = new byte[128];
+
+        /// <summary>
+        /// Title Name, UTF-8 string
+        /// </summary>
+        /// <remarks>128 bytes, UTF-8 string</remarks>
+        public byte[] TitleName { get; set; } = new byte[128];
+
+        /// <summary>
+        /// Transfer Flags, see Constants.TransferFlags
+        /// </summary>
+        public byte TransferFlags { get; set; }
+
+        /// <summary>
+        /// Size of the thumbnail image, in bytes
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int ThumbnailImageSize { get; set; }
+
+        /// <summary>
+        /// Size of the title thumbnail image, in bytes
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int TitleThumbnailImageSize { get; set; }
+
+        /// <summary>
+        /// Thumbnail image
+        /// If Metadata version = 1, 0x4000 bytes allocated, padded with zeroes
+        /// If Metadata version = 2, 0x3D00 bytes allocated, padded with zeroes
+        /// </summary>
+        public byte[] ThumbnailImage { get; set; } = [];
+
+        /// <summary>
+        /// Additional Display Names, UTF-8 string
+        /// 128 bytes per locale, 6 different locales
+        /// Only present if MetadataVersion = 2
+        /// </summary>
+        /// <remarks>If present, 768 bytes, UTF-8 string</remarks>
+        public byte[]? AdditionalDisplayNames { get; set; }
+
+        /// <summary>
+        /// Title thumbnail image
+        /// If Metadata version = 1, 0x4000 bytes allocated, padded with zeroes
+        /// If Metadata version = 2, 0x3D00 bytes allocated, padded with zeroes
+        /// </summary>
+        public byte[] TitleThumbnailImage { get; set; } = [];
+
+        /// <summary>
+        /// Additional Display Descriptions, UTF-8 string
+        /// 128 bytes per locale, 6 different locales
+        /// Only present if MetadataVersion = 2
+        /// </summary>
+        /// <remarks>If present, 768 bytes, UTF-8 string</remarks>
+        public byte[]? AdditionalDisplayDescriptions { get; set; }
+    }
+}

SabreTools.Data.Models/STFS/LicenseEntry.cs

@@ -0,0 +1,26 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// Secure Transacted File System (STFS) License Entry format
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class LicenseEntry
+    {
+        /// <summary>
+        /// License ID
+        /// </summary>
+        public long LicenseID { get; set; }
+
+        /// <summary>
+        /// License Bits
+        /// </summary>
+        public int LicenseBits { get; set; }
+
+        /// <summary>
+        /// License Flags
+        /// </summary>
+        public int LicenseFlags { get; set; }
+    }
+}

SabreTools.Data.Models/STFS/MicrosoftSignature.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// Signature block signed by Microsoft, for LIVE and PIRS format STFS files
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class MicrosoftSignature : Signature
+    {
+        /// <summary>
+        /// Signature remotely signed by Microsoft
+        /// </summary>
+        /// <remarks>256 bytes</remarks>
+        public byte[] PackageSignature { get; set; } = new byte[256];
+
+        /// <summary>
+        /// Zeroed padding
+        /// </summary>
+        /// <remarks>296 bytes</remarks>
+        public byte[] Padding { get; set; } = new byte[296];
+    }
+}

SabreTools.Data.Models/STFS/STFSDescriptor.cs

@@ -0,0 +1,57 @@
+using System.Collections.Generic;
+using SabreTools.Numerics;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Volume Descriptor, for STFS packages
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class STFSDescriptor : VolumeDescriptor
+    {
+        /// <summary>
+        /// Volume descriptor size (Should be 0x24)
+        /// </summary>
+        public byte VolumeDescriptorSize { get; set; }
+
+        /// <summary>
+        /// Reserved (Should be 0x00)
+        /// </summary>
+        public byte Reserved { get; set; }
+
+        /// <summary>
+        /// Block Separation
+        /// </summary>
+        public byte BlockSeparation { get; set; }
+
+        /// <summary>
+        /// File Table Block Count
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public short FileTableBlockCount { get; set; }
+
+        /// <summary>
+        /// File Table Block Number
+        /// </summary>
+        /// <remarks>Big-endian, 3-byte int24</remarks>
+        public Int24 FileTableBlockNumber { get; set; } = new();
+
+        /// <summary>
+        /// Top Hash Table Hash
+        /// </summary>
+        /// <remarks>20 bytes</remarks>
+        public byte[] TopHashTableHash { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Total Allocated Block Count
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int TotalAllocatedBlockCount { get; set; }
+
+        /// <summary>
+        /// Total Unallocated Block Count
+        /// </summary>
+        /// <remarks>Big-endian</remarks>
+        public int TotalUnallocatedBlockCount { get; set; }
+    }
+}

SabreTools.Data.Models/STFS/SVODDescriptor.cs

@@ -0,0 +1,56 @@
+using System.Collections.Generic;
+using SabreTools.Numerics;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Volume Descriptor, for STFS packages
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class SVODDescriptor : VolumeDescriptor
+    {
+        /// <summary>
+        /// Volume descriptor size (Should be 0x24)
+        /// </summary>
+        public byte VolumeDescriptorSize { get; set; }
+
+        /// <summary>
+        /// Block Cache Element Count
+        /// </summary>
+        public byte BlockCacheElementCount { get; set; }
+
+        /// <summary>
+        /// Worker Thread Processor
+        /// </summary>
+        public byte WorkerThreadProcessor { get; set; }
+
+        /// <summary>
+        /// Worker Thread Priority
+        /// </summary>
+        public byte WorkerThreadPriority { get; set; }
+
+        /// <summary>
+        /// Hash
+        /// </summary>
+        /// <remarks>20 bytes</remarks>
+        public byte[] Hash { get; set; } = new byte[20];
+
+        /// <summary>
+        /// Data Block Count
+        /// </summary>
+        /// <remarks>Big-endian, 3-byte uint24</remarks>
+        public UInt24 DataBlockCount { get; set; } = new();
+
+        /// <summary>
+        /// Data Block Offset
+        /// </summary>
+        /// <remarks>Big-endian, 3-byte uint24</remarks>
+        public UInt24 DataBlockOffset { get; set; } = new();
+
+        /// <summary>
+        /// Padding, should be zeroed
+        /// </summary>
+        /// <remarks>5 bytes</remarks>
+        public byte[] Padding { get; set; } = new byte[5];
+    }
+}

SabreTools.Data.Models/STFS/Signature.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Signature, differs for remotely signed (PIRS/LIVE) and console signed ("CON ") formats
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public abstract class Signature
+    {
+        // Filled in by child class, MicrosoftSignature or ConsoleSignature
+    }
+}

SabreTools.Data.Models/STFS/Volume.cs

@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// Secure Transacted File System, used by Xbox 360
+    /// There are three formats: "LIVE", "PIRS", "CON "
+    /// LIVE/PIRS are read-only signed by Microsoft, "CON " is read/write signed by console
+    /// LIVE files are only distributed via Xbox Live, PIRS can be found elsewhere (e.g. system updates)
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public class Volume
+    {
+        /// <summary>
+        /// STFS Header data
+        /// Should be 0xA000 bytes (10 blocks)
+        /// </summary>
+        public Header Header { get; set; } = new();
+
+        /// <summary>
+        /// An STFS volume contains blocks dedicated to integrity hashes
+        /// Each 4096-byte block has 170 integrity hashes for other blocks
+        /// A new hash table block exists after every 170 data blocks
+        /// i.e. First hash block is at 0x0B000 then next is at 0xB7000
+        /// </summary>
+        /// <remarks>Reader does not fill this in yet</remarks>
+        public HashTable[]? HashTables { get; set; }
+
+        /// <summary>
+        /// Data in the STFS, arranged in blocks of 4096-bytes
+        /// The Hash Table Blocks are interleaved, and ignored when numbering
+        /// i.e. Block 170 is not adjacent to Block 171
+        /// </summary>
+        /// <remarks>Too large to read into memory, left in model for posterity</remarks>
+        public byte[]? Data { get; set; }
+    }
+}

SabreTools.Data.Models/STFS/VolumeDescriptor.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Data.Models.STFS
+{
+    /// <summary>
+    /// STFS Volume Descriptor, differs for STFS and SVOD packages
+    /// </summary>
+    /// <see href="https://free60.org/System-Software/Formats/STFS/"/>
+    public abstract class VolumeDescriptor
+    {
+        // Filled in by child class, SFTSDescriptor or SVODDescriptor
+    }
+}