Press or tap to auto-type your password suffix — the full password never exists in one place.
_{The prefix stays in your mind, the suffix lives in your hand.}

This project offers a straightforward solution for securely logging into a system or website using a hardware key. By pressing a physical button connected to an ATtiny85 microcontroller, users can automate the login process, thereby reducing the risk of password exposure.

Pressing the tactile switch on the breadboard prototype sends a keystroke that appears in the terminal.

The aim of this project is to provide a more secure alternative to manually typing long or complex passwords, particularly in environments where there may be observers or surveillance. With the hardware key, users can log in quickly and securely without the risk of their password being intercepted or observed.

• Enhanced Security: Prevents password interception by keystroke loggers or shoulder surfing.
• Convenience: Simplifies the login process, especially for systems with lengthy or complex passwords.
• Privacy: Maintains the confidentiality of passwords in public or shared environments.
• Portability: Easily carried and used on multiple systems or devices.

The hardware key utilizes an ATtiny85 microcontroller with the V-USB library to implement USB Human Interface Device (HID) keyboard functionality. This allows the ATtiny85 to act as a keyboard when connected to a computer via USB. When the button connected to the ATtiny85 is pressed, it sends predefined keystrokes to the computer, automating the login process.

Sequence: (1) user types the prefix, (2) user triggers the device (tactile button or TTP223), and (3) the ATtiny85 injects suffix + Enter via USB HID. The host concatenates the parts to form the full credential.

From code to reality! The ATtiny85 Hardware Login Key project and its various prototypes. What started as a simple idea is now a fully functional set of secure login devices.

You can modify the permissions of /dev/ttyACM0 to facilitate communication with your serial device. For detailed instructions, click here.

avrdude -c avrisp -p attiny85 -P /dev/ttyACM0 -b 19200 -U lfuse:w:0xE2:m -U hfuse:w:0xDF:m

To compile the C implementation, follow these steps:

1. Open a terminal.
2. Navigate to the C_implementation folder.
3. Read the instructions or refer to using make for the C implementation.

To compile the C++ implementation, follow these steps:

1. Open a terminal.
2. Navigate to the CPP_implementation folder.
3. Read the instructions for the C++ implementation.

This hardware key uses a "Two-Piece Password" approach for enhanced security. The device does not store your full password. Instead, it stores only the complex second half, while you remember and type the simpler first half. This makes the physical key useless if it is ever lost or stolen.

Let's imagine your full, desired password is: Key_!#2025_complex

• The part you remember and type first (The Prefix): Key_
• The part stored on your hardware key (The Suffix): !#2025_complex

1. Navigate to the password field of the login form.
2. Manually type the first part of your password (e.g., Key_).
3. Plug in your hardware key.
4. Press the button on the key.
5. The key will automatically type the complex second half of the password (!#2025_complex) and press Enter, logging you in securely.

The hardware key is available in multiple PCB package versions to accommodate different assembly preferences:

• Through-Hole (DIP): Easy to assemble manually, suitable for prototyping.
  • With tactile switch.
• SMD (SOIC): For more compact and automated assembly.
  • With tactile switch.
• SMD (QFN): For advanced designs requiring a small footprint.

  • With tactile switch.

  • QFN PCB designed for a touch pad using the TTP223 IC for enhanced reliability.

    • Uses a simple high/low output for touch detection, similar to a tactile switch, providing a straightforward 0 or 1 output.
    • The PCB is designed with 4 layers to optimize signal integrity and reliability.

3D model of the hardware login key’s PCB using the Through-Hole (DIP) package in KiCad

3D model of the hardware login key’s PCB using the SMD (SOIC) package in KiCad.

3D model of the hardware login key’s PCB using the QFN package in KiCad.

3D model of the hardware login key’s PCB using the QFN package in KiCad.
With the TTP223 IC. (Uses simple high/low output for touch detection, similar to a tactile switch, with default code for straightforward 0 or 1 output.)

A 3D printed case is available for the hardware key. To use it, follow these steps:

1. Open the 3d_printed_case folder.
2. Load the hardware_key_case.stl file into your 3D printer software.
3. Print the case using your 3D printer.
4. Once printed, assemble the hardware key inside the case for added protection and aesthetics.

This project stands on the shoulders of giants. A special thank you to the developers and communities behind these essential open-source tools:

• V-USB: The core USB functionality of this hardware key is made possible by the V-USB library, a firmware-only USB driver for AVR microcontrollers from Objective Development.
• KiCad: All PCB designs were created using KiCad, a powerful, free, and open-source electronics design automation (EDA) suite. Learn more at the KiCad website.

This project is licensed under the GPLv3 License - see the LICENSE file for details.

Enjoy your secure hardware login key! Thank you for visiting Hardware-Login-Key! 🔐✨