PixPack

PixPack converts any file into a lossless PNG image and restores it byte-for-byte using a small, documented, open container format.

pixpack encode project.zip project.png
pixpack decode project.png restored.zip

The resulting PNG looks like colored noise, but every byte of the original file is preserved in the RGB pixel channels. PNG's own lossless DEFLATE compression is applied to the image data.

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Features

• Encode any file (ZIP, PDF, image, audio, video, executable, source code, text, etc.) into a PNG
• Decode the PNG back to the original file, byte-for-byte
• Inspect metadata without extracting the payload
• Verify payload integrity without extracting
• Cross-platform: Windows, Linux, macOS
• No external dependencies: single, statically-compiled binary
• SHA-256 integrity verification with constant-time comparison
• Safe filename handling: directory traversal and unsafe names are rejected
• Overwrite protection: refuses to overwrite existing files unless --overwrite is specified

How It Works

PixPack reads the input file as raw bytes and stores them in the RGB channels of each pixel:

• Red channel = byte 1
• Green channel = byte 2
• Blue channel = byte 3

The byte stream is prefixed with a binary header containing the original filename, payload length, and SHA-256 checksum. The combined data is converted to pixels, then encoded as a lossless PNG.

For a detailed technical specification, see docs/FORMAT.md.

Installation

From source (requires Go 1.24+)

git clone https://github.com/DraxonV1/PixPack.git
cd pixpack
go build -o pixpack ./cmd/pixpack

Pre-built binaries

Download the latest release from the Releases page:

Platform	Architecture	Archive
Linux	amd64	pixpack_<version>_linux_amd64.tar.gz
Linux	arm64	pixpack_<version>_linux_arm64.tar.gz
Windows	amd64	pixpack_<version>_windows_amd64.zip
Windows	arm64	pixpack_<version>_windows_arm64.zip
macOS	amd64	pixpack_<version>_darwin_amd64.tar.gz
macOS	arm64	pixpack_<version>_darwin_arm64.tar.gz

Each release includes a SHA-256 checksum file for verification.

Usage

Encode a file

pixpack encode secret.zip secret.png

With custom width:

pixpack encode secret.zip secret.png --width 512

Overwrite existing output:

pixpack encode secret.zip secret.png --overwrite

Decode a PNG

pixpack decode secret.png

This restores the file using the original filename. To specify a different output path:

pixpack decode secret.png --output restored-secret.zip

Inspect metadata

pixpack inspect secret.png

Example output:

PixPack image

Format version:  1
Filename:        secret.zip
Payload size:    174,080 bytes
Image size:      241 x 241
Checksum:        SHA-256
SHA-256:         3c88...

Verify integrity

pixpack verify secret.png

Output for a valid file:

Integrity check passed.

Get help

pixpack --help
pixpack --version

Exit Codes

Code	Meaning
0	Success
1	General error
2	Invalid CLI usage
3	Invalid or unsupported PixPack image
4	Checksum verification failure

Supported File Types

PixPack supports any file representable as bytes — there are no format restrictions:

• ZIP, TAR, GZIP archives
• Source code (any language)
• PDF documents
• Images (PNG, JPEG, GIF, WebP, etc.)
• Audio (MP3, FLAC, WAV, etc.)
• Video (MP4, MKV, AVI, etc.)
• Executables (PE, ELF, Mach-O)
• JSON, XML, YAML
• Text files
• Databases
• Any other file

Limitations

1. PixPack is NOT encryption. The data is stored as-is in PNG pixels. Anyone with PixPack can restore the file. Encrypt sensitive data separately before encoding.
2. PixPack is NOT steganography. The image looks like colored noise and clearly contains structured data. It is not designed to hide the presence of data.
3. Resizing the PNG will destroy the payload. Pixel dimensions must remain unchanged.
4. Cropping or editing pixels will likely cause checksum failure.
5. Converting to JPEG or any lossy format will destroy the payload. Only lossless PNG is supported.
6. Some websites and chat applications may recompress uploaded images. Uploading the PNG as a document/file is safer than uploading it as a photo.
7. The resulting PNG may be larger than the original file. PNG's lossless compression adds overhead, especially for already-compressed data (ZIP, video, encrypted data).
8. Huge files produce huge image dimensions and require substantial memory. A 100 MB file may produce an image around 6000x6000 pixels (~36 megapixels), requiring significant RAM during encoding and decoding.

Development

Prerequisites

• Go 1.24 or later

Commands

go build -o pixpack ./cmd/pixpack   # Build
go test ./...                        # Run tests
go test -race ./...                  # Run tests with race detector
go vet ./...                         # Static analysis
go fmt ./...                         # Format code
go test -bench=. ./...               # Run benchmarks

End-to-end test

go build -o pixpack ./cmd/pixpack
echo "Hello, PixPack!" > testdata/hello.txt

./pixpack encode testdata/hello.txt hello.png
./pixpack inspect hello.png
./pixpack verify hello.png
./pixpack decode hello.png --output restored.txt

# Compare (Unix)
cmp testdata/hello.txt restored.txt

# Compare SHA-256 (Unix)
sha256sum testdata/hello.txt restored.txt

License

MIT License — see LICENSE.

Contributing

See CONTRIBUTING.md.

Security

See SECURITY.md for reporting vulnerabilities.