ColdCard: A Review
The Coldcard is a Bitcoin-only signing device, or hardware wallet (HWW), designed and manufactured by Coinkite in Canada. The Coldcard provides physical security for your seed words. After researching the product a bit, we found out that your seed words are stored in specialized chips, designed with one purpose: to securely store secrets. All of the Coldcard code is viewable, editable, and verifiable. All Coldcard firmware is open-source, and you can compile it yourself.
After mingling with the plebs, our impression was that the Coldcard is the signing device (hardware wallet) of choice for most situations. It is important to note that the Coldcard is not as simple as a Ledger or Trezor signing device, and for good reason. Alas, it is not recommended for use if you are not willing to learn how to properly manage this level of security. We suggest a comprehensive understanding of how to use the Coldcard before securing any Bitcoin with it.
Because of the Coldcard's strong following within the community, The Bitcoin Tutor reached out to Coinkite's customer service and asked for a complimentary Experiment Bundle, which includes one Coldcard MK3, an industrial-grade microSD card, and three OpenDime USBs. An associate quickly replied that they would be happy to oblige, providing me with a link for a 100% discount and free shipping and handling. To say the least, their customer service was kind, responsive, and generous. Many thanks to Coinkite for making this review possible!
Once the bundle arrived, we eagerly tore into it and began exploring. Quite literally, every design feature of the Coldcard is geared towards security, including how the device is packaged and shipped. The Coldcard is packaged in a sealed and waterproof clear and blue bag. A barcode and serial number are prominent on the front of the bag under the company's name. Inside the bag are the Coldcard, a couple of stickers, and a small paper card that can be used to write your seed words on. There is also a plastic tag inside the bag that has a serial number on it, which should match the serial number on the front of the bag. The hardware of the device is enclosed in a clear plastic case. This is so the owner can inspect the internal components before each use to ensure the device has not been tampered with.
We started by plugging our Coldcard into a new USB charger connected to a wall outlet. The Coldcard is the only signing device (hardware wallet) with the option to avoid ever being connected to a computer, for its full life cycle: from seed generation, to transaction signing. The Coldcard also uses the PSBT (BIP 174) technology natively. We advise that you NEVER plug your Coldcard into any computer. It is worth repeating, NEVER plug your Coldcard into a computer. The Coldcard is by nature an air-gapped computer, and can remain that way forever by simply using the industrial-grade microSD card to sign transactions. I would go a step further and dedicate a new USB cable to this device, and NEVER plug this USB cable into any other computer as well. Better safe, than sorry.
The ColdCard QuickStart webpage walked us through the setup of our new Coldcard with clear instructions. It can be set up in minutes. The Coldcard is compatible with a wide range of desktop wallets, such as Electrum and Sparrow. It is also great for creating multiple-signature wallets (multi-sig). Typically, once you create a transaction, you will transfer a signature from the Coldcard to the wallet using the MicroSD card. Creating and transferring a signature is easy and takes minutes. We personally use our Coldcard in conjunction with keys.casa for enhanced security. It's a simple, secure way to hold and distribute your own keys with peace of mind that your bitcoin is safe. By protecting your bitcoin with multiple keys, each stored on a separate device for added protection, your Bitcoin will be untouchable. We have been using the Coldcard for over a year now and could not be happier with this signing device. It meets all of our security needs, is user-friendly, and is a pleasure to handle. Years from now, I wouldn't be surprised if this device was passed down to my children for safe keeping.