OPacker

a small, self-contained encrypted asset bundler:

• Recursively packs all files from assets/ into a encrypted .bin using AES-256-GCM
• Generates and saves a 256-bit encryption key to assets.key
• Encryption AAD (based on asset item file path) plus package-wide AAD (based on .bin file path)
• Runtime loader decrypts assets (textures, bytes, etc.) in the package

Features

• Zero external dependencies
• AES-256-GCM with random IVs per chunk
• Simple JSON index encrypted inside the package

Usage

1. Build the packer

odin build demo -out:opacker

2. Pack the assets

./opacker

It will:

• Scan the assets/ folder
• Encrypt everything with a random key
• Write assets.key - don't ship it with the game!
• Produce assets.bin

Demo:

Packed: assets/cloud.png (12345 bytes)
...
Asset package created: assets.bin (987654 bytes total)
Loaded assets/cloud.png with dimensions 512x512

Security notes

• Encryption is industry standard AES-256-GCM
• Package filename is used as AAD for the header and index
• Each asset uses full path as extra AAD → renaming or moving files inside the package will fail decryption
• Not military-grade obfus, but will stop the casual ripper
• Do not ship assets.key with release

TODO

• Compression before encryption
• Decompression after decryption
• Streaming en/decryption for large assets
• Mem-map package instead of loading all at once

Made with ❤️ under MIT by algoboyz