attiny-pass-key

Type your password effortlessly.

Context

Typing your password, sometimes, can be a pain. For instance, when you dont have a keyboard connected directly to the device you want to access. Or maybe you have a passphrase so large and complex that it is a hassle to type it every time.

THIS PROJECT IS MADE FOR EDUCATIONAL PURPOSES ONLY. USE AT YOUR OWN RISK.

Purpose

This project is designed for the ATtiny microcontroller (specifically the Digispark/ATtiny85) to implement a passkey system. It acts as a USB keyboard device that automatically types a configured password when plugged in or triggered. This enables secure access control using a simple, compact hardware setup.

Features

• Automated Password Entry: Types a pre-configured password via USB HID.
• Compact Codebase: Optimized for ATtiny microcontrollers.
• Configurable: Password can be set via environment variables.

Tools Used

• Arduino CLI: For building and uploading firmware.
• mise: For task management and tool versioning.
• ATtiny85 / Digispark: The target hardware platform.
• Standard Arduino Libraries: DigiKeyboard for USB HID functionality.

Getting Started

Prerequisites

• mise: This project uses mise to manage dependencies and tasks. Install it by following the installation guide.
• Hardware: A Digispark or ATtiny85 development board.

Setup

1. Clone the repository:

   git clone <repo-url>
   cd attiny-pass-key

2. Install Tools: Run mise install to download the required version of arduino-cli and other tools defined in mise.toml.

   mise install

3. Initialize Environment: Run the setup task to configure the Arduino core and libraries.

   mise run setup

   This command will:

   • Create a .env file from .env.example if it doesn't exist.
   • Update the Arduino core and library indexes.

4. Configure Password: Open the .env file and set your desired password in the ATTINY_PASS_KEY_PASSWORD variable.

   ATTINY_PASS_KEY_PASSWORD="your_secure_password_here"

Build and Upload

This project uses mise tasks to simplify the build process.

1. Compile the Firmware:

   mise run arduino:compile

   This compiles the sketch and injects the password from your .env file.

2. Upload to Device:

   mise run arduino:upload

   Connect your Digispark/ATtiny85 when prompted (or within the 60-second timeout window typical for Micronucleus bootloaders).

3. Monitor (Optional): To view serial output (if enabled/supported):

   mise run arduino:monitor

Project Structure

• attiny-pass-key.ino: The main Arduino sketch containing the logic.
• mise.toml: Configuration for mise, defining tools and tasks (compile, upload, setup).
• arduino-cli.yaml: Configuration file for arduino-cli.
• sketch.yaml: Defines the board profile (FQBN) and platform dependencies.
• .env: Stores sensitive configuration like the password (do not commit this file).