pdvzip

Embed a ZIP or JAR file within a PNG image, to create a tweetable and "executable" PNG polyglot file.
Share the image on X/Twitter and a few other hosting sites, which will retain the embedded archive.

With pdvzip, you can embed a ZIP/JAR file up to a maximum size of *2GB (cover image + archive file).

*Compatible sites, listed below, have their own much smaller size limits:-

X/Twitter (5MB), Flickr (200MB), ImgBB (32MB), PostImage (32MB), ImgPile (8MB).

Image credit: @obeca

Based on the similar idea by David Buchanan, from his original Python program tweetable-polyglot-png,
pdvzip uses different methods for storing and extracting embedded files within a PNG image.

The Linux/Windows extraction script is stored within the iCCP chunk of the PNG image. The embedded ZIP/JAR file is stored within the last IDAT chunk of the image.

(You can try the pdvzip Web App, here, if you don't want to download and compile the CLI source code.)

Usage (Linux)

user1@linuxbox:~/Downloads/pdvzip-main/src$ g++ main.cpp -O2 -s -o pdvzip
user1@linuxbox:~/Downloads/pdvzip-main/src$ sudo cp pdvzip /usr/bin

user1@linuxbox:~/Desktop$ pdvzip

Usage: pdvzip <cover_image> <zip/jar>
       pdvzip --info

user1@linuxbox:~/Desktop$ pdvzip my_cover_image.png document_pdf.zip

Created PNG-ZIP polyglot image file: pzip_55183.png (4038367 bytes).

Complete!

user1@linuxbox:~/Desktop$ pdvzip my_cover_image.png hello_world.jar

Created PNG-JAR polyglot image file: pjar_19662.png (1016336 bytes).

Complete!

Extracting Your Embedded File(s)

Important: When saving images from X/Twitter, click the image in the post to fully expand it, before saving.

The following section covers the extraction of embedded ZIP files. JAR files are covered later.

pdvzip (for Linux) will attempt to automatically set executable permissions on newly created polyglot image files.

You will need to manually set executable permissions using chmod on these polyglot images downloaded from hosting sites.

Twitter.ZIP.Folder.mp4

Linux - using bash (or sh) shell environment.

user1@linuxbox:~/Desktop$ ./pzip_55183.png

For any other Linux shell environment, you will probably need to invoke bash (or sh) to run the image file.

linuxbox% bash ./pzip_55183.png 

Alternative extraction (Linux). Using wget to download and run the image directly from the hosting site.
X/Twitter wget example: Image with embedded python script.

wget -O Fibo.png "https://pbs.twimg.com/media/GLXTYeCWMAAA6B_.png";chmod +x Fibo.png;bash ./Fibo.png

Windows (Rename the image file extension to '.cmd')

G:\demo> ren pzip_55183.png pzip_55183.cmd
G:\demo> .\pzip_55183.cmd

Alternative extraction (Windows). Using iwr to download and run the image directly from the hosting site.
Flickr iwr example: Image with embedded mp4 video file.

iwr -o swing.cmd "https://live.staticflickr.com/65535/54025688614_2f9d474cba_o_d.png";.\swing.cmd

Opening the .cmd file from the desktop, on its first run, Windows may display a security warning.
Clear this by clicking 'More info' then select 'Run anyway'.

To avoid security warnings, run the file from a Windows console, as shown in the above example.

For common video & audio files, Linux will use the vlc or mpv media player. Windows uses the default media player.

PDF - Linux will use evince or firefox. Windows uses the default PDF viewer.
Python - Linux & Windows use python3 to run these programs.
PowerShell - Linux uses pwsh (if installed), Windows uses either powershell.exe or pwsh.exe to run these scripts. Folder - Linux uses xdg-open, Windows uses powershell.exe with II (Invoke-Item) command, to open zipped folders.

For any other file type within your ZIP file, Linux & Windows will rely on the operating system's set default method/application. Obviously, the compressed/embedded file needs to be compatible with the operating system you run it on.

If the archive file is JAR or the compressed file type within the ZIP archive is PowerShell, Python, Shell Script or a Windows/Linux Executable, pdvzip will give you the option to provide command-line arguments for your file, if required.

Make sure to enclose arguments containing spaces, such as file & directory names, within "quotation" marks. e.g.

user1@linuxbox:~/Desktop$ ./pdvzip my_cover_image.png jdvrif_linux_executable.zip

For this file type you can provide command-line arguments here, if required.

Linux: -e ../my_cover_image.jpg "../my document file.pdf"

Also, be aware when using arguments for the compressed ZIP file types (not JAR), you are always working from within the subdirectory "pdvzip_extracted".

pdvzip.web.app.mp4

To just get access to the file(s) within the ZIP archive, rename the '.png' file extension to '.zip'.
Treat the ZIP archive as read-only, do not add or remove files from the PNG-ZIP polyglot file.

Executing Embedded Java Programs

Linux Option 1:

user1@linuxbox:~/Desktop$ java -jar pjar_19662.png
Note: If you use this method to run your embedded Java program, you will have to manually add command-line
      arguments (if required) to the end of the command, as your embedded arguments will not work with
      this method. e.g.
      user1@linuxbox:~/Desktop$ java -jar ./pjar_19662.png -u john_s -a 42 -f "John Smith"

Linux Option 2a, using bash (or sh) shell environment:

user1@linuxbox:~/Desktop$ ./pjar_19662.png
Note: This method will execute the embedded Java program and also use any embedded
      command-line arguments with the Java program.

Linux Option 2b, using any other shell environment, you will need to invoke bash (or sh) to execute the image:

linuxbox% bash ./pjar_19662.png

Windows Option 1:

PS C:\Users\Nick\Desktop\jar_demo> java -jar .\pjar_19662.png 
Note: If you use this method to run your embedded Java program, you will have to manually add command-line
      arguments (if required) to the end of the command, as your embedded arguments will not work with
      this method. e.g.
      PS C:\Users\Nick\Desktop\jar_demo> java -jar .\pjar_19662.png -u john_s -a 42 -f "John Smith"

Windows Option 2:

PS C:\Users\Nick\Desktop\jar_demo> ren .\pjar_19662.png .\pjar_19662.cmd
PS C:\Users\Nick\Desktop\jar_demo> .\pjar_19662.cmd
Note: This method will execute the embedded Java program and also use any
      embedded command-line arguments with the Java program.

pdvzip_jar_args.mp4

PNG Image Requirements for Arbitrary Data Preservation

PNG file size (image + archive file) must not exceed the hosting site's size limits.
The site will either refuse to upload your image or it will convert your image to jpg, such as X/Twitter.

Dimensions:

The following dimension size limits are specific to pdvzip and not necessarily the extact hosting site's size limits. These dimension size limits are for compatibility reasons, allowing it to work with all the above listed platforms.

PNG-32/24 (Truecolor)

Image dimensions can be set between a minimum of 68 x 68 and a maximum of 899 x 899.

Note: Images that are created & saved within your image editor as PNG-32/24 that are either black & white/grayscale, images with 256 colors or less, will be converted by X/Twitter to PNG-8 and you will lose the embedded content. If you want to use a simple "single" color PNG-32/24 image, then fill an area with a gradient color instead of a single solid color. X/Twitter should then keep the image as PNG-32/24. (Example).

PNG-8 (Indexed-color)

Image dimensions can be set between a minimum of 68 x 68 and a maximum of 4096 x 4096.

PNG Chunks:

With X/Twitter, for example, you can overfill the following PNG chunks with arbitrary data,
in which the platform will preserve as long as you keep within the image dimension & file size limits.

bKGD, cHRM, gAMA, hIST,
iCCP, (Limited size chunk. Only 10KB max. with X/Twitter).
IDAT, (Use as last IDAT chunk, after the final image IDAT chunk).
PLTE, (Use only with PNG-32/24 images).
pHYs, sBIT, sPLT, sRGB,
tRNS. (Use only with PNG-32/24 images).

Other platforms may differ in what chunks they preserve and which ones you can overfill.

pdvzip uses the chunks iCCP (stores extraction script) and IDAT (stores the ZIP/JAR file) for your arbitrary data.

ZIP/JAR File Size & Other Important Information

To work out the maximum ZIP/JAR file size, start with the size limit, minus the image size, minus 1500 bytes (extraction script size).

X/Twitter example: (5MB limit) 5,242,880 - (307,200 [image] + 1500 [extraction script]) = 4,934,180 bytes available for your ZIP/JAR file.

• Make sure your ZIP/JAR file is a standard ZIP/JAR archive, compatible with Linux unzip & Windows Explorer.

• Do not include more than one .zip file within the main ZIP archive. (.rar files are ok).

• Do not include other pdvzip created PNG image files within the main ZIP archive, as they are essentially .zip files.

• Use file extensions for your file(s) within the ZIP archive: my_doc.pdf, my_video.mp4, my_program.py, etc.

  A file without an extension within a ZIP archive will be considered a Linux executable.

• Paint.net application is recommended for easily creating compatible PNG image files.

Third-Party Libraries

This project includes the following third-party library:

• LodePNG by Lode Vandevenne
  • License: zlib/libpng (see LICENSE file)
  • Copyright (c) 2005-2024 Lode Vandevenne