OpenMagicKeyboard

Windows 11 x64 driver and app for the Apple Magic Keyboard A3203 (USB-C, 2024, no Touch ID — USB VID_05AC&PID_0320, Bluetooth VID&0001004C_PID&0320). Works over Bluetooth and USB-C with one shared profile. Original MIT-licensed code.

Current version: 0.4.0.0. Build output goes to artifacts\Release (not committed; see Build from source).

What you get:

• fn / Globe key (sent to Windows as F23), fn + delete = forward Delete, fn + arrows = Home / End / Page Up / Page Down
• F1–F12 as media / brightness keys (or standard F-keys, or locked fn)
• Remap Control, Option, Command, Caps Lock and Shift (e.g. Ctrl ⇄ Cmd)
• ISO § / ` key swap, battery level (Bluetooth)

Install

Requirements: Secure Boot off and Windows test signing on, because the driver is signed with a local test certificate, not by Microsoft. Windows then shows a "Test Mode" watermark. Build and sign the package first (see Build from source).

1. Open the app: artifacts\Release\MagicKeyboardGui.exe
2. Click Install driver (or run scripts\setup.ps1 in PowerShell) and approve the Windows prompt.
3. If test signing was off, setup turns it on and asks you to restart Windows. After the restart click Install driver again.
4. Setup binds the driver to the keyboard on every connection (USB-C and Bluetooth), verifies it loaded, removes any older project versions, and registers a recovery task.

Then pick your mappings in the app and click Apply to keyboard (also File → Apply, Ctrl+Enter). Options → Start with Windows and Options → Start minimized at sign-in keep the app in the notification area; click its tray icon to open it. Minimizing the window also sends it to the tray. The keyboard reconnects for a moment. With an icon F-key mode, the small media helper starts automatically with Windows.

Command-line equivalents (they relaunch elevated):

.\scripts\setup.ps1 -Action Status       # what is installed and loaded (read-only)
.\scripts\setup.ps1 -EnableTestSigning   # install / repair
.\scripts\setup.ps1 -Action Uninstall    # back to the Microsoft driver (-RestoreVendor: Magic Utilities)

Safety net

If the driver ever cannot load — for example because test signing was switched off by an update — a keyboard with a broken lower filter would stop typing. The OpenMagicKeyboard Recovery scheduled task checks at every boot and switches only the affected Apple keyboard back to the Microsoft driver. Run setup again to reinstall.

Troubleshooting

App says	Do this
Driver blocked by Windows	Test signing is off. Click Repair driver, restart, click it again.
Using the Magic Utilities driver	Click Install driver. Magic Utilities stays installed; -RestoreVendor switches back.
Driver not installed	Click Install driver.
Keyboard not connected	Pair over Bluetooth or use a USB-C data cable.
Bluetooth won't reconnect after charging with the cable	Known Magic Keyboard behavior on Windows: cabling changes its Bluetooth pairing key. Remove "Magic Keyboard" in Settings → Bluetooth & devices and pair again; the driver attaches automatically.

Setup logs are saved under observations\setup-*.

Build from source

Needs Visual Studio with Desktop C++ and the WDK (installed on this PC).

.\scripts\build.ps1 -Target Driver -Analyze          # driver package -> artifacts\Release\package
.\scripts\new-test-certificate.ps1 -Execute          # once per PC, elevated; prints a thumbprint
.\scripts\sign-package.ps1 -Thumbprint <thumbprint> -Execute
.\scripts\build.ps1 -Target DeviceBinding -Analyze
.\scripts\build.ps1 -Target Gui
.\scripts\build.ps1 -Target DriverTests -Analyze; .\scripts\test-driver.ps1   # host fuzz tests
.\scripts\test-gui.ps1; .\scripts\test-gui-layout.ps1

Test certificates expire (12 months by default); when yours does, create a new one and re-sign.

Layout

Path	Contents
driver/	KMDF lower filter (USB MI_01 + Bluetooth HID), descriptor parser and remapper
tools/Gui/	The app (WinForms, .NET Framework 4.8) and media helper
tools/DeviceBinding/	Binds a specific driver to one exact keyboard devnode
tools/HidProbe/, tools/DriverTests/	Metadata probe and host tests
scripts/	Build, sign, setup, tests
docs/	Background notes from development (protocol findings, Bluetooth details)

Version history

• 0.4.0.0 — fixed the driver failing to load: older packages were left staged and Windows later picked one whose service file had been deleted (Problem 39 / 0xC000003A). Setup now keeps exactly one package. Control channel no longer stops working when USB-C and Bluetooth are both present; one profile applies to both; fn works without the three-tap check; new app UI with battery level; one-step setup and boot-time recovery.
• 0.3.0.1 — Bluetooth path and native brightness keys. 0.2 — fn combinations and icon modes. 0.1 — first USB filter.