LIT Format Guide

Purpose

This guide provides comprehensive documentation for working with Microsoft Reader LIT (eBook) files using Cabriolet. LIT is Microsoft’s proprietary format for electronic books used in Microsoft Reader.

References

• Getting Started Guide

• LIT CLI Commands

• LZX Compression Guide

• Ruby API Reference

Concepts

What is a LIT File?

LIT (Literature) files are Microsoft’s eBook format used in Microsoft Reader, commonly found in:

• Electronic books and novels

• Technical documentation

• Digital textbooks

• Magazine and newspaper archives

• Self-published eBooks

The format uses LZX compression and optionally DRM encryption.

LIT File Structure

A LIT file is structured as a compound document:

┌─────────────────────────┐
│   LIT Header            │  File signature and metadata
├─────────────────────────┤
│   Manifest              │  Book metadata and structure
├─────────────────────────┤
│   Content Streams       │
│   ┌─────────────────┐   │
│   │ HTML Content    │   │  Book text (LZX compressed)
│   ├─────────────────┤   │
│   │ Images          │   │  Embedded images
│   ├─────────────────┤   │
│   │ Metadata        │   │  Title, author, etc.
│   ├─────────────────┤   │
│   │ DRM Info        │   │  Optional encryption data
│   └─────────────────┘   │
└─────────────────────────┘

LIT Header: Contains format version and file metadata.

Manifest: Book structure, table of contents, and metadata.

Content Streams: HTML text, images, and other book content.

DRM Info: Optional DES encryption information (if DRM-protected).

Compression Support

LIT files use LZX compression for content:

• LZX compression - High compression ratio for text

• Configurable window size

• Optimized for HTML and text content

For detailed algorithm information, see link:.

DRM Encryption

LIT files can be encrypted with DRM:

• DES encryption - Data Encryption Standard

• Owner-specific keys - Tied to Microsoft Reader activation

• Decryption limitation - Cabriolet does not support DRM decryption

Cabriolet cannot decrypt DRM-protected LIT files. Only unencrypted LIT files can be extracted.

eBook Metadata

LIT files contain rich metadata:

• Title - Book title

• Author - Author name(s)

• Publisher - Publisher information

• ISBN - International Standard Book Number

• Cover art - Embedded cover image

• Table of contents - Chapter structure

Basic Operations

Checking LIT Files

Check if a LIT file is encrypted:

Command-line

cabriolet info book.lit

# For explicit format specification:
cabriolet info --format lit book.lit

Ruby API

require 'cabriolet'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

puts "Version: #{header.version}"
puts "Encrypted: #{header.encrypted? ? 'Yes (DES)' : 'No'}"
puts "Files: #{header.files.size}"

if header.encrypted?
  puts "\nWARNING: This file is DRM-encrypted."
  puts "Decryption is not supported."
end

decompressor.close(header)

Example Output

LIT File Information
==================================================
Filename: book.lit
Version: 1
Encrypted: No
Files: 15

Files:
  content.html
    Size: 524,288 bytes
    Compression: LZX
  cover.jpg
    Size: 32,768 bytes
    Compression: none
  metadata.xml
    Size: 2,048 bytes
    Compression: LZX

Extracting LIT Files

Extract content from unencrypted LIT files:

Command-line

# Extract to current directory
cabriolet extract book.lit

# Extract to specific directory
cabriolet extract book.lit output/

# For explicit format specification:
cabriolet extract --format lit book.lit output/

Ruby API

require 'cabriolet'
require 'fileutils'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

# Check for encryption
if header.encrypted?
  puts "Error: File is DRM-encrypted"
  decompressor.close(header)
  exit 1
end

# Extract all files
FileUtils.mkdir_p('output')
count = decompressor.extract_all(header, 'output')

decompressor.close(header)
puts "Extracted #{count} files to output/"

Getting LIT Information

Display detailed LIT file information:

Command-line

cabriolet info book.lit

# For explicit format specification:
cabriolet info --format lit book.lit

Ruby API

require 'cabriolet'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

puts "Version: #{header.version}"
puts "Encrypted: #{header.encrypted? ? 'Yes (DES)' : 'No'}"
puts "Files: #{header.files.size}"

header.files.each do |file|
  compression = file.compressed? ? "LZX" : "none"
  encryption = file.encrypted? ? " [encrypted]" : ""

  puts "\n#{file.filename}"
  puts "  Size: #{file.length} bytes"
  puts "  Compression: #{compression}#{encryption}"
end

decompressor.close(header)

Creating LIT Files

Build new LIT files from HTML and images:

Command-line

# Create with LZX compression (default)
cabriolet create book.lit content.html cover.jpg

# Create without compression
cabriolet create --no-compress book.lit content.html

# For explicit format specification:
cabriolet create --format lit --no-compress book.lit content.html

Ruby API

require 'cabriolet'

compressor = Cabriolet::LIT::Compressor.new

# Add HTML content with compression
compressor.add_file('content.html', 'content.html', compress: true)
compressor.add_file('metadata.xml', 'metadata.xml', compress: true)

# Add images without compression
compressor.add_file('cover.jpg', 'cover.jpg', compress: false)
compressor.add_file('image1.png', 'images/image1.png', compress: false)

bytes = compressor.generate('book.lit')
puts "Created book.lit (#{bytes} bytes)"

Advanced Features

Encryption Detection

Detect and handle encrypted files:

require 'cabriolet'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

if header.encrypted?
  puts "This LIT file is DRM-encrypted with DES."
  puts "Decryption requires:"
  puts "  - Original Microsoft Reader installation"
  puts "  - Valid activation key"
  puts "  - Owner-specific decryption key"
  puts "\nCabriolet cannot decrypt DRM-protected files."
else
  puts "This LIT file is not encrypted."
  puts "Content can be extracted freely."
end

decompressor.close(header)

File-level Encryption

Check individual file encryption status:

require 'cabriolet'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

header.files.each do |file|
  status = if file.encrypted?
    "encrypted"
  elsif file.compressed?
    "compressed (LZX)"
  else
    "uncompressed"
  end

  puts "#{file.filename}: #{status}"
end

decompressor.close(header)

Selective Compression

Control which files are compressed:

require 'cabriolet'

compressor = Cabriolet::LIT::Compressor.new

# Compress text content for better ratio
compressor.add_file('chapter1.html', 'chapter1.html', compress: true)
compressor.add_file('chapter2.html', 'chapter2.html', compress: true)
compressor.add_file('toc.xml', 'toc.xml', compress: true)

# Don't compress already-compressed media
compressor.add_file('cover.jpg', 'cover.jpg', compress: false)
compressor.add_file('audio.mp3', 'audio.mp3', compress: false)

compressor.generate('book.lit')

Content Organization

Organize eBook content hierarchically:

require 'cabriolet'

compressor = Cabriolet::LIT::Compressor.new

# Add book structure
compressor.add_file('metadata.xml', 'metadata.xml', compress: true)
compressor.add_file('toc.xml', 'toc.xml', compress: true)

# Add chapters
Dir.glob('chapters/*.html').sort.each do |chapter|
  internal_path = "chapters/#{File.basename(chapter)}"
  compressor.add_file(chapter, internal_path, compress: true)
end

# Add images
Dir.glob('images/*').each do |image|
  internal_path = "images/#{File.basename(image)}"
  compressor.add_file(image, internal_path, compress: false)
end

compressor.generate('organized-book.lit')

Performance Optimization

Compression Selection

Choose compression wisely:

Content Type	Compress?	Reason
HTML/XML	Yes	Excellent compression ratio (60-80%)
Plain text	Yes	Very good compression (50-70%)
JPEG images	No	Already compressed
PNG images	Maybe	Small PNGs might benefit
Audio/Video	No	Already compressed

Extraction Performance

Extract efficiently:

require 'cabriolet'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('large-book.lit')

# Efficient: Extract all at once
count = decompressor.extract_all(header, 'output/')

# Avoid: Extracting files one by one
# (Has decompression overhead for each file)

decompressor.close(header)

Common Use Cases

eBook Conversion

Convert LIT books to other formats:

require 'cabriolet'
require 'fileutils'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

# Check for DRM
if header.encrypted?
  puts "Cannot convert: File is DRM-encrypted"
  decompressor.close(header)
  exit 1
end

# Extract content
FileUtils.mkdir_p('conversion')
decompressor.extract_all(header, 'conversion/')

# Find HTML content
html_files = Dir.glob('conversion/**/*.html')
puts "Found #{html_files.size} HTML files for conversion"

# Convert to other formats...
# (Use external tools like pandoc)

decompressor.close(header)

Metadata Extraction

Extract book metadata:

require 'cabriolet'
require 'nokogiri'

decompressor = Cabriolet::LIT::Decompressor.new
header = decompressor.open('book.lit')

# Find metadata file
metadata_file = header.files.find { |f| f.filename =~ /metadata\.xml/i }

if metadata_file
  # Extract and parse metadata
  temp_file = 'temp_metadata.xml'
  decompressor.extract_file(metadata_file, temp_file)

  doc = Nokogiri::XML(File.read(temp_file))

  puts "Title: #{doc.at_xpath('//title')&.text}"
  puts "Author: #{doc.at_xpath('//author')&.text}"
  puts "Publisher: #{doc.at_xpath('//publisher')&.text}"

  File.delete(temp_file)
end

decompressor.close(header)

Creating Custom eBooks

Build custom LIT eBooks:

require 'cabriolet'

compressor = Cabriolet::LIT::Compressor.new

# Create metadata
metadata = <<~XML
  <?xml version="1.0"?>
  <metadata>
    <title>My Custom Book</title>
    <author>John Doe</author>
    <publisher>Self Published</publisher>
  </metadata>
XML

File.write('metadata.xml', metadata)
compressor.add_file('metadata.xml', 'metadata.xml', compress: true)

# Add content
compressor.add_file('introduction.html', 'intro.html', compress: true)
compressor.add_file('chapter1.html', 'chapter1.html', compress: true)
compressor.add_file('epilogue.html', 'epilogue.html', compress: true)

# Add cover
compressor.add_file('cover.jpg', 'cover.jpg', compress: false)

bytes = compressor.generate('my-book.lit')
puts "Created custom eBook: #{bytes} bytes"

Troubleshooting

Common Errors

"LIT file is DRM-encrypted"

The file has DRM protection. Cabriolet cannot decrypt:

cabriolet info book.lit
# Shows encryption status

DRM decryption is not supported. You need the original Microsoft Reader with valid activation.

"Invalid LIT signature"

The file is not a valid LIT file:

# Check file type
file book.lit

"Decompression failed"

LZX decompression error. File may be corrupted:

# Try extracting specific files
cabriolet info book.lit  # List files
# Extract uncompressed files only

"NotImplementedError"

Feature not yet implemented (e.g., DRM decryption):

# Check what's supported
cabriolet info book.lit

Validation

Verify LIT file before processing:

require 'cabriolet'

begin
  decompressor = Cabriolet::LIT::Decompressor.new
  header = decompressor.open('book.lit')

  puts "LIT file is valid"
  puts "Version: #{header.version}"

  if header.encrypted?
    puts "WARNING: File is DRM-encrypted"
    puts "Extraction not possible"
  else
    puts "Files: #{header.files.size}"
    puts "Extraction possible"
  end

  decompressor.close(header)
rescue Cabriolet::FormatError => e
  puts "Invalid LIT file: #{e.message}"
rescue NotImplementedError => e
  puts "Feature not supported: #{e.message}"
end

Best practices

1. Check for DRM first: Always verify encryption status before attempting extraction

2. Compress text, not media:

   • Compress HTML, XML, CSS

   • Don’t compress JPEG, MP3, or other compressed formats

3. Preserve structure: Maintain original file organization when extracting

4. Handle errors gracefully: Account for DRM and unsupported features

5. Respect copyright: DRM exists to protect content rights

6. Test thoroughly: Verify extracted content is complete and valid

Format Specifications

File Signature

LIT files use a compound document structure:

Offset  Bytes  Description
0x0000  8      Compound document signature
0x0008  ...    Storage structure

Encryption

• Algorithm: DES (Data Encryption Standard)

• Key derivation: Based on Microsoft Reader activation

• Scope: Can be applied to individual files or entire book

Compression

• Algorithm: LZX

• Window size: Configurable

• Applied to: HTML content, XML metadata, CSS

For complete format specifications, see Format Specifications.

Limitations

Cabriolet has the following limitations with LIT files:

1. No DRM decryption: Cannot extract DRM-protected files

2. Read-only metadata: Cannot modify existing metadata

3. Basic creation: Creates simple LIT files without advanced features

4. No digital signatures: Cannot add or verify signatures

Next steps

• Learn about LZX compression

• Review extracting files

• Study Ruby API

See also

• CHM Format

• HLP Format

• All Format Guides

Bibliography

• Cabriolet on GitHub

• Wikipedia: Microsoft Reader

• ConvertLIT - LIT Conversion Tool