Coinkite, the maker of Bitcoin-only hardware wallets, recently released MK5, a significant quality of life and user experience upgrade to the MK4 Coldcard, building on the strong security foundation set by its predecessor. The MK5 comes in many colors and styles. Today I’ll be reviewing the Orange and Glow in the dark versions and their form factor and user experience upgrades to answer the question: are the device upgrades worth the money?
Building on the well-known and trend-setting MK4 security platform, which brought two secure element chips from different manufacturers and an MCU to the same device. The MK5 instead focuses on quality of life, improving NFC connectivity, reworking the buttons and plastic chassis of the hardware wallet, as well as adding a much larger screen, among other new features. This is the first hardware upgrade to the Coinkite MK line since the launch of the MK4 in 2022, incorporating some of the technologies that the Coldcard Q debuted in 2023.
What’s new with the MK5 Coldcard?
The major upgrades to the UX are immediately visible; for example, the screen is much larger, perhaps 30% larger. Their announcement blog describes it as a “1.54-inch display protected by Gorilla Glass,” which looks and feels much sturdier than older models.
The next obvious upgrade is the buttons. Unlike the MK4 buttons, which are recessed, requiring your fingers to enter the socket to make a click, the MK5 buttons are almost flush with the device’s chassis, making them much easier to press. The press feels good, it clicks, giving the user solid tactile feedback. Much more comfortable than the warm, slightly uncomfortable, unresponsive touch screen feel seen in other hardware wallets.
You also quickly notice that the chassis has been redesigned. The screen section no longer jumps over the keyboard; instead, it’s all one rectangle with pleasantly curved edges. It looks more modern, more elegant, while maintaining the cypherpunk transparency that reveals the underlying hardware, a signature design principle of Coinkite products.
The MK5 also comes with a button and screen protector half case that slides and clicks in and out. It can be removed completely and fits perfectly from the back of the device, revealing the USB power input at the bottom of the device without any problems.
NFC Push transactions
Last but not least, Coinkite is doubling down on NFC support with the MK5. An acronym for near field communication, the NFC antenna is an increasingly popular technology stack in the Bitcoin industry. From NFC tap to pay lightning bolt cards with cool designs and laser eyes, or Coinkite’s own Tapsigners, to Cashu’s tap to send features developed by Calle.
NFC is a powerful alternative to other wireless connectivity technologies like Bluetooth or Wifi that some hardware wallet providers have adopted, but comes with some debatable drawbacks, primarily their range. Unlike the alternatives, NFC has a short range. we are talking about centimeters in range, whereas Bluetooth and Wi-Fi are talking about tens of meters. So the paranoid-level threat that someone with a long-range antenna pointed at your house might catch a transaction in transit or be able to connect to your device remotely disappears.
There is also no multi-step device protocol with NFC; phones either turn the feature on and off, the app starts scanning and transmission can occur. No pin codes, no traversing lists of Bluetooth-powered devices. Much simpler UX in theory. It is also far superior in terms of user experience to SD card transmission of pre-signed transactions back and forth from laptops or phones. Although NFC may technically cross the ‘air-gapped’ line in the MK4 and MK5, NFC still has the best qualities of all wireless connectivity options and is turned off by default. Similar to the ability to connect the MK5 to a computer via USB for data transmission, the NFC antenna can also be detached at the hardware level by scratching off a specific wire in the hardware.
Coinkite’s NFC push Tx software is open source and much less in terms of lines of code than Bluetooth or Wifi. The full NFC push Tx code is open source. The client webapp side of the protocol has no defined license and is presumably intended to be integrated by any web application. While the hardware side of the code is public but restricted by the non-commercial use license.
The colors of the MK5
Playing into the Bitcoiner’s hunger for collectibles, the MK5 comes in a wide variety of cases such as gold flake transparent grey, beautiful orange and even glow in the dark! I got to play with the orange and blue glow-in-the-dark version, though I kind of wish I’d gotten my hands on the gold-flecked one.
Nevertheless, the designs are beautiful, transparent enough to see the hardware but colorful enough to be stylish. This is how they look in practice.
Supply Chain Security
The packaging was also very interesting; the box with the hardware came with a purchase order for the items, which were inside tamper-proof security bags. These bags had pretty strong plastic, not something you can tear easily and it takes a knife to cut through them. The bags were also marked with a unique number, which can be seen in the pictures below. Inside the bag was another plastic strip containing the same number. And when the devices were first turned on, they showed the same number on the screen. This is a flash memory code that is configured per device at the factory. Makes eavesdropping and manipulation of hardware firmware much more difficult. The next level would be to notify the user of the bag number via email or behind a page login so they can also have a side channel to verify the number.
If you see something about the packaging, you are encouraged to take pictures and contact Coinkite support.
The battery and exposed hardware unit pictured below is the COLDPOWER adapter from Coinkite, which I happened to have lying around and figured I’d also test. It’s meant to power the device completely air-gapped, no cables connected to any computer at all, as even a rogue Wifi repeatedly plugged into an outlet could transmit signals over the power lines (lol).
Things to improve?
Integration of NFC Push Tx with mobile wallets was a bit inconsistent. I tried Cove, Bull Bitcoin and Nunchuck. Of the three, Nunchuck had the best integration, with Cove not far behind. Bull Bitcoin seems to have disabled the feature or hidden it quite well. Cove is a young project that will likely improve leaps and bounds in the coming months, while Nunchuck a very advanced and powerful wallet took me a few minutes to figure out but ultimately turned out to be the best interface of the three.
Even with a stronger NFC antenna, I had to remove my phone’s ridiculously thick case to get a reliable data transmission, but it’s not the end of the world.
Conclusion: Is the MK5 worth the money to upgrade?
As a proud owner of what I now realize is an old MK3, the move to a MK5 is a significant upgrade, and the low cost of $167 plus shipping, I’d say it’s a no-brainer. That’s a whole generation of security and UX upgrades I didn’t realize I needed.
For active users of the MK4, the larger screen and better buttons are definitely a quality of life improvement, and the better NFC antenna is likely to pay dividends by smoothing the transaction flow as well. Again, compared to other hardware wallets on the market, the price is very reasonable.
However, for passive MK4 owners who make a few transactions a year, the juice may not be worth the squeeze. They still get firmware updates and get all the security benefits, and probably won’t miss the improved UX that much.
Disclaimer: Coinkite provided Bitcoin Magazine with a pair of free MK5 Coldcards to use for the purpose of testing their product for review.