USB HID Client

Android app that allows you to easily use your phone as a keyboard and mouse

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Table of Contents

1. About The Project
2. Getting Started
   • Prerequisites
3. Usage
4. Roadmap
5. Contributing
6. License
7. Acknowledgments

About The Project

This Android app allows you your phone to present itself to a connected device as a keyboard and mouse. Since this happens at a very low level, the connected device sees it exactly as a normal keyboard and mouse, meaning you don't need to install any software on the connected computer! For this reason, it will even work if the connected device is in its BIOS/UEFI. Even multimedia keys are supported, meaning you can send volume up/down keys to the connected computer to control media.

Disclaimers:

• This app requires your device to be rooted.
• I strongly recommend using a keyboard such as Unexpected Keyboard to use special keys such as modifier and function keys, but most functionality will work with any standard Android keyboard.

Bonus description for nerds: This app adds (and provides a simple UI for you to communicate with) two character devices (/dev/hidg0 and /dev/hidg1 respectively) by adding HID functions to the default Android USB gadget. If you wanted to, you could just use this app to create the character devices, then communicate solely through some C program, shell script, or whatever else you wanted as long as it had the right permissions to access the character devices and knew how to send proper reports to them. Beware of SELinux policies if you do that though. If anyone is actually doing that, let me know, I'd be glad to help if necessary.

Tested primarily on: Linux (Host computer) and Pixel 5 running Android 14.

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Getting Started

Prerequisites

• Rooted device running Android
  • Only specific root methods are supported, because I need to patch SELinux policy at runtime and am using provided tools to do so. if your root method isn't on this list and provides a method for live-patching SELinux policy, feel free to create an issue.
    • Magisk: magiskpolicy
    • KernelSU: ksud sepolicy patch
  • Android version that I currently test with: 14
• Soft Keyboard
  • I test the app with Gboard, Unexpected Keyboard, and used to test Hacker's keyboard, but Unexpected Keyboard is the one with better support, more keys, and less issues .
  • Important Hacker's Keyboard settings to change:
    • Key behavior settings > Ctrl key code = None (Ignored when not modifying other keys)
    • Key behavior settings > Alt key code = None (Ignored when not modifying other keys)
    • Key behavior settings > Meta key code = None (Ignored when not modifying other keys)

Installation (Binary)

The recommended way to install the app is through the IzzyOnDroid repo via an app that's compatible with F-Droid style repositories, since that'll make updates much easier. However, you can also download the APK file from the Github releases page, then install it on your Android device.

Installation (Source)

Clone the repository.

git clone https://github.com/Arian04/android-hid-client.git

import into Android Studio, build the APK, then install it on your Android device.

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Usage

To relay keys in real-time as soon as you press them, click on the keyboard icon in the menu bar. It should pull up your keyboard. Now you can just start typing!

Typing in the "Manual Input" text box will send all the characters that you've typed into the box to the connected device once you hit the "send" button.

Some Use Cases

• Quickly be able to change BIOS/UEFI settings of a computer when you don't have a keyboard with you
• Typing a long string (such as a password or IP address) into a console

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Roadmap

• Keyboard support
• Add some special key buttons to the UI (like multimedia keys)
• Touchpad support
• Ability to send string all at once
• Add full settings page
• Add prompt to create /dev/hidgX if not present

See the open issues for a full list of proposed features (and known issues).

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Contributing

Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

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License

Distributed under the GNU GPLv3 License. See LICENSE.txt for more information.

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Acknowledgments

• IzzyOnDroid for adding this app to his F-Droid repository
• Best-README-Template

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