Hardware Features

Callouts Diagram

Callout Description
1 Display (128x64 pixels, OLED)
2 MicroUSB connection to PC.
3 MicroSD card slot. Push to eject.
4 Genuine light (Green)
5 Caution light (Red)
6 Numeric keypad. Plus X (Cancel/Refuse) and OK (Checkmark/Accept). Arrows keys on 5,7,8,9 for menus.
7 DFU Button (hole). Not used outside of the factory.

Micro SD Cards

Micro-USB Cable Required

Genuine / Caution Lights

There are two lights (LED's) marked as Genuine (green) and Caution (red). These lights are directly connected to the Secure Element of the Coldcard. Their purpose is to indicate the flash contents have not changed since your last use of the Coldcard.

When you power up the Coldcard, you should see a Verifying... screen and then the green (genuine) LED will light. This means the flash memory has the correct contents. There is no way for trojan software to change this light to green without your PIN.

Obviously, the Coldcard from the factory will have a green light, and after each firmware upgrade, we update the checksum that is performed so the light will be green again. The only time you should see a red light is during a firmware upgrade process (the first time you enter the PIN after the upgrade), and briefly during power-up sequence when the verification is on-going.

Important

Do not enter your PIN code into what might look like your Coldcard if the light is red! You should assume someone has tampered with it's firmware, and it might operate normally, but in fact be trying to steal your money.

For more technical background on this security feature please have a look at this whitepaper.