% metadata, exif, sanitization, privacy

# ============================================================================
# EXIFTOOL - Universal Metadata Tool
# ============================================================================

# Install exiftool
sudo apt install libimage-exiftool-perl

# View all metadata
exiftool <file>
$ file: echo -e "photo.jpg\ndocument.pdf\nvideo.mp4"

# View specific metadata tags
exiftool -GPS* <image_file>
$ image_file: echo "photo.jpg"

# Remove ALL metadata
exiftool -all= <file>
$ file: echo -e "photo.jpg\ndocument.pdf"

# Remove metadata and keep original
exiftool -all= -o <output_file> <input_file>
$ output_file: echo "cleaned.jpg"
$ input_file: echo "original.jpg"

# Remove metadata from all files in directory
exiftool -all= *.jpg

# Remove GPS data only
exiftool -gps:all= <image>
$ image: echo "photo_with_location.jpg"

# Remove specific tags
exiftool -Author= -Creator= <file>
$ file: echo "document.pdf"

# Batch remove metadata (preserve originals)
exiftool -all= -r <directory>
$ directory: echo -e "~/Pictures\n~/Documents"

# Remove metadata WITHOUT creating backup files
exiftool -all= -overwrite_original <file>
$ file: echo "photo.jpg"

# ============================================================================
# MAT2 - Metadata Anonymisation Toolkit
# ============================================================================

# Install mat2
sudo apt install mat2

# Check if file contains metadata
mat2 --check <file>
$ file: echo -e "document.pdf\nphoto.jpg\naudio.mp3"

# Remove metadata
mat2 <file>
$ file: echo -e "document.pdf\nimage.png"

# Clean file with lightweight mode (faster, less thorough)
mat2 --lightweight <file>
$ file: echo "large_image.jpg"

# Clean and specify output location
mat2 --output-directory <output_dir> <file>
$ output_dir: echo "/tmp/cleaned"
$ file: echo "document.pdf"

# List supported file types
mat2 --list

# ============================================================================
# PDF SANITIZATION
# ============================================================================

# Remove PDF metadata with exiftool
exiftool -all:all= document.pdf

# Clean PDF with mat2
mat2 document.pdf

# PDF metadata removal with pdftk
pdftk input.pdf output output.pdf compress

# Remove PDF metadata with qpdf
qpdf --linearize --object-streams=generate input.pdf output.pdf

# Print PDF and scan (nuclear option - removes ALL metadata/tracking)
# lp input.pdf
# (Scan printed pages back to PDF)

# ============================================================================
# IMAGE METADATA REMOVAL
# ============================================================================

# Remove EXIF from JPG (exiftool)
exiftool -all= -overwrite_original photo.jpg

# Remove EXIF with jhead
jhead -purejpg <image>
$ image: echo "photo.jpg"

# Remove EXIF with ImageMagick (also recompresses)
convert <input> -strip <output>
$ input: echo "original.jpg"
$ output: echo "cleaned.jpg"

# Remove EXIF from PNG
exiftool -all= image.png

# Batch clean all images
exiftool -all= -overwrite_original -r ~/Pictures/

# ============================================================================
# AUDIO/VIDEO METADATA
# ============================================================================

# Remove metadata from MP3
eyeD3 --remove-all <audio_file>
$ audio_file: echo "song.mp3"

# Remove metadata from video (ffmpeg)
ffmpeg -i input.mp4 -map_metadata -1 -c:v copy -c:a copy output.mp4

# Strip metadata from all videos in folder
for file in *.mp4; do ffmpeg -i "$file" -map_metadata -1 -c copy "cleaned_$file"; done

# ============================================================================
# OFFICE DOCUMENTS
# ============================================================================

# Remove Word/Excel/PowerPoint metadata (LibreOffice)
# File → Properties → Reset Properties → Clear All

# CLI: Convert to PDF (removes some metadata)
libreoffice --headless --convert-to pdf document.docx

# Remove metadata from Office docs with exiftool
exiftool -all= document.docx

# ============================================================================
# DOCUMENT SANITIZATION WORKFLOW
# ============================================================================

# Complete document sanitization:
# 1. Remove metadata
exiftool -all= -overwrite_original document.pdf

# 2. Convert to different format and back (removes hidden data)
pdftk document.pdf output temp.pdf compress
qpdf --object-streams=generate temp.pdf sanitized.pdf

# 3. Verify metadata removed
exiftool sanitized.pdf

# ============================================================================
# CHECKING FOR HIDDEN DATA
# ============================================================================

# Check for hidden text/layers in PDF
pdfinfo <pdf_file>
$ pdf_file: echo "document.pdf"

# Extract all text from PDF (find hidden content)
pdftotext <pdf_file> -
$ pdf_file: echo "document.pdf"

# Check PDF structure
pdftk <pdf_file> dump_data
$ pdf_file: echo "document.pdf"

# Analyze document for hidden data
binwalk <file>
$ file: echo "suspicious_document.pdf"

# ============================================================================
# COMMON METADATA FIELDS TO REMOVE
# ============================================================================

# Images:
# - GPS coordinates (location)
# - Camera make/model
# - Date/time taken
# - Software used
# - Author/Creator

# PDFs:
# - Author, Creator, Producer
# - Creation/Modification dates
# - Software version
# - Comments/annotations
# - Hidden text/layers

# Office Docs:
# - Author, Company
# - Edit history
# - Comments/tracked changes
# - Template information
# - Filesystem paths

# Audio/Video:
# - Artist, Album, Genre
# - Creation date
# - GPS coordinates (videos)
# - Camera/recording device info

# ============================================================================
# SAFE SHARING WORKFLOW
# ============================================================================

# Before sharing any file:
# 1. Check metadata
exiftool file.jpg

# 2. Remove metadata
mat2 file.jpg

# 3. Verify removal
exiftool file.cleaned.jpg

# 4. (Optional) Convert format
convert file.cleaned.jpg -quality 95 file_final.jpg

# 5. Final check
exiftool file_final.jpg

# ============================================================================
# GUI TOOLS
# ============================================================================

# GIMP (image editor)
# File → Export → Uncheck "Save EXIF data"

# Metadata Cleaner (GUI for mat2)
# Install: flatpak install flathub fr.romainvigier.MetadataCleaner

# ExifCleaner (cross-platform GUI)
# https://exifcleaner.com

# ============================================================================
# BEST PRACTICES
# ============================================================================

# Always check files before sharing
# Use mat2 or exiftool as default

# For sensitive documents: Convert to image, then back to PDF
# (Removes all hidden data/metadata)

# Screenshots are safer than photos
# (No GPS, camera info)

# Use disposable/anonymous accounts for sharing
# Even without metadata, file itself may be traceable

# Consider: Print → Scan → OCR for max sanitization
# Nuclear option, but removes ALL tracking

# Test your workflow
# Remove metadata, check with exiftool, verify

# ============================================================================
# BATCH PROCESSING SCRIPTS
# ============================================================================

# Clean all images recursively
find ~/Pictures -type f \( -name "*.jpg" -o -name "*.png" \) -exec exiftool -all= -overwrite_original {} \;

# Clean all PDFs in directory
for pdf in *.pdf; do mat2 "$pdf"; done

# Clean and organize
#!/bin/bash
for file in *; do
    exiftool -all= -overwrite_original "$file"
    mv "$file" "cleaned_$file"
done

# ============================================================================
# VERIFICATION
# ============================================================================

# Verify no GPS data
exiftool -GPS* photo.jpg | grep -i gps

# Verify no author info
exiftool -Author -Creator document.pdf

# Check file size (cleaned should be smaller)
ls -lh original.jpg cleaned.jpg

# ============================================================================
# TROUBLESHOOTING
# ============================================================================

# exiftool not removing metadata
# Try: exiftool -all:all= (removes more)

# mat2 "Unsupported file format"
# Check: mat2 --list for supported types

# PDF still has metadata after cleaning
# Try converting: pdftk → qpdf → exiftool chain

# File corrupted after cleaning
# Always test on copy first
# Some formats don't support metadata removal