citrust

A fast 3DS ROM decryption tool, written in Rust. Drop-in replacement for b3DSDecrypt.py — roughly 4× faster.

---

✨ Features

• Decrypts .3ds ROM files in-place — no extra disk space needed
• All encryption methods supported: Original (KeyX 0x2C), Key7x (0x25), Key93 (0x18), Key96 (0x1B)
• Hardware-accelerated AES — automatic AES-NI detection, zero configuration
• Memory-mapped I/O with zero-copy decryption
• Parallel decryption across all CPU cores
• CLI for scripting and automation
• GUI with a SteamOS-friendly design (large buttons, dark theme, Steam Deck resolution)

🚀 Performance

ROM Size	Python (b3DSDecrypt)	citrust	Speedup
1.84 GB	4.73 s	1.16 s	4.1×

📸 GUI

Launch citrust-gui, click Select ROM File, click Decrypt — done.

📥 Installation

Download (recommended)

Grab the latest release for your platform:

👉 GitHub Releases — Linux and Windows binaries available.

Build from source

git clone https://github.com/londospark/citrust.git
cd citrust
cargo build --release -p citrust-cli    # CLI only
cargo build --release -p citrust-gui    # GUI (needs a display server)

Requires Rust 1.85+ and an x86_64 CPU (AES-NI recommended for full performance).

🔑 Key Setup (Required)

citrust requires an aes_keys.txt file containing your 3DS encryption keys. This is the same format used by Citra, Azahar, and other 3DS emulators — if you already have one, citrust can use it directly.

The GUI will prompt you to select a key file on first launch. Once provided, keys are saved automatically and you won't need to do this again.

Where citrust looks for keys (checked in order):

Location	Platform
./aes_keys.txt (next to the ROM or current directory)	All
~/.config/citrust/aes_keys.txt	Linux / SteamOS
%APPDATA%\citrust\aes_keys.txt	Windows
~/.local/share/citra-emu/sysdata/aes_keys.txt	Linux (Citra)
~/.local/share/azahar-emu/sysdata/aes_keys.txt	Linux (Azahar)
%APPDATA%\Citra\sysdata\aes_keys.txt	Windows (Citra)

You can also specify a path explicitly with --keys (CLI) or the Browse button (GUI).

Dumping keys from your 3DS

You can dump keys from your 3DS hardware using GodMode9. See the GodMode9 usage guide for instructions.

🔧 Usage

CLI

citrust path/to/rom.3ds                   # uses auto-detected key file
citrust path/to/rom.3ds --keys keys.txt   # use a specific key file

The ROM is decrypted in-place. citrust auto-detects the encryption method and handles everything.

GUI

1. Launch citrust-gui
2. On first run, click Browse for Key File and select your aes_keys.txt
3. Keys are saved automatically — you won't see this step again
4. Click Select ROM File
5. Click Decrypt
6. Done

🏗️ Architecture

citrust is a Cargo workspace with three crates:

Crate	Type	Description
citrust-core	Library	Crypto, ROM parsing, decryption logic
citrust-cli	Binary	Command-line interface
citrust-gui	Binary	GUI application (egui/eframe)

🙏 Credits

• Original Python decryption tool: b3DS by b1k
• AI team management: Squad by Brady Gaster