Building a Final Key

Final Key

Remembering passwords is a pain, and there’s a number of devices out there to make it easier. If you’re looking to roll your own, this guide to building a Final Key will walk you through the process.

We talked about the Final Key before. It’s a one button password manager that encrypts and stores your password. It acts as a virtual serial port for configuration. When you hit the button, it becomes a keyboard and types in the correct password.

The creator has no intentions of making this a commercial project for a number of reasons. Instead, easy build instructions are provided based on the Arduino Pro Micro. The 24LC512 EEPROM can be soldered directly to the Arduino by bending out the DIP legs. A few resistors, a button, and an LED finish off the project. The last step is to fill it with hot glue to prevent tampering.

The Final Key firmware is available on Github, and the case can be ordered from Shapeways. If you’re interested in hardware password management, you can also check out the Mooltipass which is being developed on Hackaday.

[Thanks to Lars for the tip!]

Are We Not Indestructible? We Are Quiz Buttons!

In what we hope is a new trend in interviewing, some of the people at [Anthony]‘s place of work asked him to make some wireless quiz buttons. He took the task quite seriously, making them extremely robust and low-power.

[Anthony] is experienced in the button arts, having made this party push button for a wedding reception. His design for the quiz buttons is a little different. Each button has an Arduino Pro mini and an nRF24L01 wireless RF module. On the receiver side is an Arduino Pro micro and an another RF module. A connected PC captures the serial data and  displays the pressed button’s ID. It also shows the order in which subsequent buttons were pressed and the time elapsed between them.

The really notable part of this build aside from the awesome laser-cut MDF Devo energy dome button housings is the extremely low power consumption of the transmitting Arduinos. [Anthony] has designed them to go into sleep mode which disables all on-board circuitry and only wakes on interrupt. He removed the power LED and the voltage regulator since they run on 2-AA batteries. The voltage regulator was drawing more than 25mA in sleep mode. Because of these mods, each button consumes < 1μA, which is less power than the batteries can self discharge over their lifetime.

[Thanks Jef]