The hardware wallet market has exploded recently, with new models shipping weekly. Many are no longer mere clones of Ledger or Trezor, offering unique forms and features. This week, Bitcoin.com received the Coldcard, a BTC wallet from Coinkite that promises to be 'cheap and ultra-secure.' Here is a detailed review.
Coldcard or Cheap Calculator?
The Coldcard looks and feels like a cheap calculator. It is light, plasticky, and more akin to a mass-produced gadget from Alibaba than a cutting-edge hardware wallet. The unit shipped from Canada to a UK reviewer was even labeled as a calculator on the customs form, though that did not prevent a $20 import tax on the $70 device. The translucent design exposes the circuitry, which may not appeal to everyone, but the reviewer appreciates its rawness. Close inspection reveals the words 'Genuine Caution' printed above the micro SD slot.
Out of the bag (no cable or box included), the wallet appears disarmingly flimsy. However, this is not necessarily a drawback. In design terms, there are two types of hardware wallets: ones so beautiful you want to show them off, and ones so ugly you toss them in a drawer. Guess which is less likely to be stolen? Coldcard is not a coffee-table accessory, and for bitcoin's sake, that is probably a good thing.
Getting to Know the Coldcard
Coldcard uses the BIP39 standard for seed phrases, based on 2,048 words, offering 128-bit security. More interestingly, it adopts BIP 174, becoming the first hardware wallet to support this multisig standard for partially signed bitcoin transactions, enabling air-gapped wallets to sign transactions offline.
When connected via micro USB, the device springs to life with instructions on a 128×64 OLED screen—small but readable. However, button responsiveness is poor. Buttons often fail to register on the first, second, or even third press, exacerbated by the lack of haptic feedback. This is likely an early production issue, but it may alienate users accustomed to the snappy buttons of the Ledger Nano.
Early Days but Positive Signs
Despite its humble appearance, the Coldcard has generated buzz in cryptocurrency circles, partly because it comes from Coinkite, creator of the Opendime USB stick that lets BTC be spent like a bearer bond. Coinkite admits it is early days, and with new features and bug fixes, the wallet will improve.
Setup involves creating a two-part PIN and recording two anti-phishing words. Users can then create a new wallet or import an existing one. Choosing the former requires recording a 24-word seed, scrolling repeatedly as only three words appear at a time. After recording, the device prompts recall of each word in random order, choosing from three options. This is tedious, compounded by occasional unregistered button presses, though a submenu offers touch sensitivity adjustment.
Simple When You Know How
A surprise lurks in the submenus: Coldcard also functions as a Litecoin wallet. While controls are not always intuitive, the quickstart guide clears up confusion. To create a BTC address, users must download the Electrum desktop wallet and connect it via USB or, for air-gapped operation, by writing a new-wallet.json file to a micro SD card. This may seem excessive but appeals to those seeking ultra-security.
After trial and error, the reviewer successfully connected Coldcard to Electrum, created a BTC address, and attempted to deposit a small amount from an exchange. Initial errors occurred because many exchanges still do not support bech32 addresses, though platforms like Kraken are integrating. Switching to legacy addresses worked smoothly: a 2.5 mBTC deposit arrived, and sending a portion prompted transaction signing via the Coldcard.
Aside from button issues and fragility, the Coldcard is impressive. It is not for novices, but experienced users who want to isolate funds from internet-connected devices while retaining signing capability will appreciate it.