Coinkite is the only Bitcoin hardware wallet developer, recently released MK5, a key quality and user experience upgrade to MK4 Coldcard, building on the strong security foundations laid by its predecessor. The MK5 comes in many colors and styles. Today, I will review Orange and Glow in black versions, along with their feature form and user experience improvements, to answer the question: is the device upgrade worth the money?
Building on the well-known and trend-setting MK4 security platform, it brings two secure element chips from different manufacturers and an MCU to the same device. The MK5 focuses on quality of life, improving NFC connectivity, redesigning the buttons and the plastic chassis of the hardware wallet, and adding a much larger screen, among other new features. This is the first hardware upgrade in the Coinkite MK line since the launch of the MK4 in 2022, which incorporates some of the technology that Coldcard Q will release in 2023.
What’s new with the MK5 Coldcard?
Major UX improvements are immediately apparent; the screen, on the other hand, is much bigger, maybe 30% bigger. Their announcement blog describes it as a “1.54-inch display protected by Gorilla Glass,” which looks and feels more durable than older models.
The next obvious improvement is the buttons. Unlike the MK4’s buttons, which are bolted on, requiring your fingers to fit into the socket to click, the MK5’s buttons are almost flush with the phone’s chassis, making them much easier to press. The press feels good, it clicks, it gives the user a solid tactile feedback. It’s much more comfortable than the warm, uncomfortable, unresponsive touch screen feel, as seen in some hardware bags.
And you can see right away that the chassis has been redesigned. A section of the screen no longer protrudes above the keyboard; instead, it’s all one rectangle with comfortable curved edges. It looks modern, very elegant, while keeping that cypherpunk shine that reflects the underlying hardware, a signature design principle of Coinkite products.
The MK5 comes with a button and half case screen protector that slides and clicks in and out. It can be completely removed and fits perfectly from the back of the device, revealing the USB power input at the bottom of the device without removing it.
NFC Push Transactions
Finally, Coinkite is doubling down on NFC support with the MK5. Short for near field communication, the NFC antenna is a very popular technology stack in the Bitcoin industry. From NFC tap to pay Lightning Bolt cards with beautiful designs and laser eyes, or Coinkite’s Tapsigners, to the Cashu tap to send features developed by Calle.
NFC is a powerful alternative to other wireless connection technologies such as Bluetooth or Wifi, which some hardware wallet providers have adopted, but it comes with a debatable downside, especially its range. Unlike other methods, NFC is short distance by design; we’re talking about centimeters in distance, while Bluetooth and Wi-Fi are about tens of meters. So the paranoid-level threat that someone with a long-range note pointed at your house might intercept your transactions if they’re in transit or able to connect to your remote device, disappears.
And there is no multi-step device connection protocol with NFC; phones can have the feature turned on and off, the app starts scanning, and the transfer is possible. No pins, no filtering the list of Bluetooth-enabled devices. UX is very simple in concept. It is also superior in terms of user experience for SD card transfers of pre-signed transactions back and forth from laptops or phones. Although NFC may technically bypass the ‘wireless’ line on the MK4 and MK5, NFC still has all the wireless connectivity options, and is set up automatically. Similar to the option to connect the MK5 to a computer via USB to transfer data, the NFC antenna can also be disabled at the hardware level by scratching a specific wire inside the hardware.
Coinkite’s NFC push Tx software is open source and much smaller in terms of lines of code than Bluetooth or Wifi. The full NFC push Tx code is open source. The client web application side of the protocol has no defined license and is assumed to be intended for integration by any web application. While the hardware side of the code is in the public domain, it is limited by a non-commercial license.
MK5 colors
Playing to Bitcoiner’s hunger for collectibles, the MK5 comes in a variety of finishes, such as shiny gold gray, beautiful orange and even glow in the dark! I got to play with the orange and blue glow-in-the-dark version, though I wish I could have gotten my hands on the gold one.
Still, the designs are nice, plain enough to see the hardware, but colorful enough to be stylish. Here’s how they look in action.
Supply Chain Security
The packaging was also very interesting; the box containing the hardware came with the purchase order for the items, which were inside tamper-evident security bags. These bags were made of hard plastic, not something you can tear easily, requiring 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 piece of plastic with the same number. And when the devices are turned on for the first time, they show the same number on the screen. This is the flash memory code programmed into each device at the factory. Making guesswork and manipulation of hardware firmware more difficult. The next level will be to notify the user of the wallet number by email or after logging into the site, so they have a side channel to verify the number.
If you see something off with the package, you are encouraged to take pictures and reach out to Coinkite support.
The battery and hardware device pictured below is Coinkite’s COLDPOWER Adapter, which I happened to have laying around and figured I’d check it out as well. It is intended to power the device completely sealed in air, no cables are connected to any computer, since even a rogue Wifi connected to a power outlet can transmit signals on power lines (lol).
Things to improve?
NFC Push Tx integration with mobile wallets was a little inconsistent. I tried Cove, Bull Bitcoin and Nunchuck. Of the three, Nunchuck had the best synergy, with Cove not far behind. Bull Bitcoin seems to have disabled the feature or hidden it well. Cove is a small project that may improve leaps and bounds in the coming months, while Nunchuck is a more advanced and powerful wallet, it took me a few minutes to find but in the end it turned out to be the best interface of the three.
Even with a powerful NFC antenna, I had to remove my ridiculously thick phone case to get reliable data transfer, but that’s not the end of the world.
Conclusion: Is the MK5 worth the upgrade money?
As the proud owner of what I now consider to be a classic MK3, moving to the MK5 is a significant upgrade, and for the low cost of $167 plus shipping, I’d say it’s a no-brainer. That’s a whole generation of security and UX improvements I didn’t realize I needed.
For active users of the MK4, the bigger screen and better buttons are definitely a quality of life improvement, and a better NFC antenna will likely yield benefits as well for making the experience flow better. Also, compared to other hardware bags in the market, the price is very reasonable.
For passive MK4 owners who do a few things a year, however, the juice may not be worth the squeeze. They still get firmware updates and get all the security benefits, and they probably won’t miss the much improved UX.
Disclaimer: Coinkite provided Bitcoin Magazine with a few free MK5 Coldcards to use for the purpose of testing their product for review.
