Monday, 5 August 2013

Inside Bitfrore Part 2 - Hardware

Please support our Indiegogo campaign to make the Bitfrore - Bitcoin Paper Wallet a reality.

This is part 2 in a series of posts on the Bitfrore technology.
Click here to view Part 1 - Bitfrore Basic Components

In the previous post we talked about the basics of Bitfrore. Now lets take a closer look at the actual hardware.

Bitfrore has 2 major internal components.
  • Dot-Matrix Printer Mechanism
  • Custom Motherboard

Printer Mechanism
Bitfrore uses an Epson-M190 shuttle impact printer1.
This printer uses standard paper and prints by firing a pin at a ribbon against the paper. This type of printing is older and slower than thermal printing but has been proven over time to have superior archival qualities.

Bitfrore was explicitly designed to use a dot matrix printer to avoid the problems of thermal printouts fading over time.

Bitfrore uses a custom printer driver that randomizes the pin firing sequence making it much more difficult to recreate the key by listening to the sound of the pins being fired2 and because the Epson M-190 uses a looped ribbon that is continuously re-used even Columbo couldn't read the private key off the used part of the ribbon3.


This prototype PCB shows Bitfrore's inner simplicity.

At the bottom of the board is the NXP LPC1114  microcontroller, the brains of the operation that contains the Bitfrore paper wallet printing software.

On the left of the board is the random number generator that feeds random numbers directly into the microcontroller.

Above the microcontroller are the power transistors used to drive the solenoids and motor in the printer.

On the right is the power supply for the microcontroller and the connector to the front panel controls.

There is no hidden complexity just the exact right components to get the job done.

The Combination
These simple components are combined to make the internals of the Bitfrore Paper Wallet Printer. 

Add a box and some exterior controls and you get the simplest and safest way to print a Bitcoin Paper Wallet.

Continue To Part 3 - Continuous Confidence Tests



  1. Very cool. It's nice to see you're far more paranoid than I am; I wouldn't have considered acoustic or spent ribbon attacks at all.

    With such compact components, why do you leave so much empty space in the case?

    1. An earlier prototype was battery powered. The empty space housed the batteries.

    2. Hi,
      Please send me your email id.