Coldcard Review: Is it a Safe Air-Gapped Wallet in 2021?

Hardware wallets are used to store cryptocurrency securely. The market offers many hardware wallets, and Coldcard is one of the top hardware cryptocurrency wallets. They are easy to use, secure, and open-source hardware wallets. Moreover, they are manufactured in Canada. Therefore, in this article, we will do a Coldcard review.

FeaturesDescription
Physical AppearanceThey are lightweight, pocket-sized devices 
ConnectivityAir-gapped
BatteryIt is not required. Coldcard wallets draw energy from a USB power pack or AC adaptor. 
HardwareThey use a secure element to store secrets. Microchip’s ATECC608A is used to store the 24-word seed phrase for your BIP32/BIP39 wallet.
SecurityThe wallets are entirely secure from supply chain attacks, phishing, and more. They use different types of PINs such as Duress PIN and Brick me PIN to secure the wallet.
Cryptocurrency supportBitcoin and Bitcoin Testnet
Compatibility with other appsThey support several third-party apps such as Electrum, Casa, BlueWallet, Sparrow, and more
Cost$179.99

Summary

  • Coldcard offers easy-to-use hardware wallets.
  • They are user-friendly and light in weight
  • The wallets are air-gapped secure devices.
  • It does not require a battery and draw power from a USB connection
  • They use various measures to secure the device from different kinds of attacks.
  • Further, they support Bitcoin and Bitcoin testnet.
  • Bitcoin seed plate allows you to store the recovery seed phrase. 

Coldcard Review: Physical Appearance

Display128 x 64 px white OLED
Size88 x 51 x 9 mm 
Weight30gm

In addition, Coldcard wallets also offer a full-sized numeric keypad to enter the pin quickly. 

Coldcard
Coldcard

Coldcard Review: Connectivity

These wallets are air-gapped, and therefore, they do not need to connect to a smartphone or desktop instead, it draws energy from an AC power adaptor or USB power pack. Further, it consumes 20mA to 40mA power approximately. Also, if you wish, you can connect it to Coldcard Adaptor, a 9V battery.

Battery

Coldcard wallets do not require a battery.

Hardware

Coldcard wallets do not trust the main microprocessor with the secrets; instead, they use a secure element to protect your cryptocurrencies. This element is Microchip’s ATECC608A, which stores your master secret: the 24-word seed phrase for your BIP32/ BIP39 wallet. Moreover, the communication is completely secure from complex challenges and prevents eavesdropping and replay. 

Additionally, they also offer a debug mode that can be accessed after entering the PIN. It allows you to type python commands directly into the product. Furthermore, the entire firmware is written in MicroPython. You can use this to create new features, create special transactions, or signing requests. The firmware updates are signed by the factory private key.

Coldcard Hardware
Coldcard Hardware

Coldcard Review: Security

Supply Chain attacks

The supply chain attacks are prevented using two techniques – 

  1. Coldcard uses a tamper-evident clear plastic bag to pack the wallets. There is a unique number present in the bag that matches Coldcard’s secure element. This number cannot be changed, and you are told to verify this number while powering up your device for the first time at your location. 
  1. The secure element and other sensitive parts of the coldcard are covered with epoxy. 

This makes it difficult to change the wiring around them or remove any chip. In addition, a factory private key signs the firmware updates. 

Physical Security

Coldcard wallets offer a clear case to check if there has been any hardware implant in the device. 

Further, the firmware is signed using a factory key to protect your wallet against Evil Maid attacks. Each byte of the flash memory is verified with a red/green light set. The light status is changed by a dedicated circuitry connected directly to the secure element. These lights are also covered with epoxy so that any physical tampering by those maids will also be visible. 

Different types of PIN

The PIN code of your Coldcard wallet is divided into two parts. After you enter the first part, you will see two words on the screen. These phrases are unique for all PIN prefixes. Therefore, you need to remember them and check them before entering the second part of your PIN. In addition, these pins protect you against Trojan horse attacks. 

Also, they offer a duress PIN that works similar to the primary PIN of the wallet, but the bitcoin key generated is not the main key. If you want, you can also put some bitcoin in the duress wallet to make it more real. 

In addition, beware of the “BRICK ME” PIN, which destroys the secure element and makes your wallet worthless. The wallet also supports BIP39 passphrases to create an unlimited supply of distraction wallets.  

Please note that if you forget your pin, then there is nothing that can be done. However, there is a ‘SHOOT THIS’ label that can be used for device destruction. Further, you get 13 attempts in total to enter the correct pin. After you enter the correct pin, the counter will be restored. If not, then the device will brick itself. So, save your key somewhere safe.

SHOOT THIS
SHOOT THIS

If you don’t trust a random number generator, you can also prefer dice rolls to generate the BIP39 seed phrase. You have to press 1-6 for each roll (99 rolls recommended). Based on your rolls, you will receive a properly encoded seed phrase.

Coldcard Review: Backup and Recovery

The Coldcard offers two options for backup – 

MicroSD Card

​​You can backup unsigned and signed transactions offline using a microSD card. Moreover, you can use any card that has been formatted as FAT32 and equivalent and is smaller than 32GB. To backup your transactions using a MicroSD card, you have to click on Advanced-> Backup-> Backup Systems.

You don’t need to worry about the security, as the data stored in the card is AES 7z encrypted. Furthermore, each backup file is password protected and doesn’t have any connection in between. Also, If you don’t want to encrypt the backup because you have to remember the passphrase, you can also opt for a clear text backup. 

The backup text files can be signed if less than 500Mb and do not contain the word signed in its name. You can also add messages up to 240 characters long with some restrictions on spaces and newlines.

It also allows checking whether the backup is completed by performing checksum checks on encrypted files. Moreover, this does not require any password. Additionally, the SD card can also be used for firmware upgrades and joining multi-sig wallets

Coldcard Backup Messages
Coldcard Backup Messages

Coldcard seedplate

The Coldcard seedplate is a bitcoin backup metal plate. This plate comprises twelve words per side. Its size is 12.7 x 7.62 cm with a tough 2mm thick steel. The etch marks are chemically coloured in black for better legibility. Moreover, it is quite affordable and one of the best options available for safe backup.

Coldcard seed plate
Coldcard seed plate

How do I restore my Coldcard?

If your backup is encrypted, you must remember the passphrase to restore your wallet. For restoring, you should select “Advanced-> Backups-> Clone Coldcard” and then select the encrypted file. Then press “Ok.” Now your data has been restored, and the device has rebooted. All your details have been duplicated except the PIN code. 

Cryptocurrency Support

Coldcard supports Bitcoin and Bitcoin Testnet. However, they do not support Altcoins. 

Compatibility with other Apps 

Coldcard does not have its proprietary application. However, it supports several independent applications mentioned as follows –

  • Electrum 
  • BTCPay
  • Specter-Desktop
  • Wasabi wallet
  • Fully Noded
  • Unchained capital
  • Casa
  • BlueWallet
  • Coldcore
  • Sparrow

Generally, Electrum is connected to Coldcard. Therefore, it is quite easy to connect. Additionally, you can also set up a multi-sig wallet using a Coldcard. 

Coldcard Review: Opendime

The Coldcard Opendime is a USB stick also known as a Bitcoin Stick. It is like a piggy bank; you have to destroy it to spend it. 

It has the following features –

  • You can spend Bitcoin like FIAT.
  • Also, you can pass it multiple times.
  • To check balance, you need to connect it using a USB. Moreover, you can easily verify using the chrome plugin. It acts as a read-only flash drive. 
  • It is completely secure. The private key is generated in the device, and it is not known to anyone, not even you!
  • Further, it also uses bitcoin message signing and private keys in WIF format. 
  • No miner fees
  • In addition, no confirmation delays
Coldcard Opendime
Coldcard Opendime

Coldecard Review: Pricing

Model NamePrice (USD)Price( EUR)
Coldcard179.99152.46
Coldcard Seedwallet49.9742.33
Coldcard MicroSD card37.9432.44
Coldcard Opendime (3)5950.44

Additionally, you should never buy a used Coldcard wallet from E-bay or any similar online store. The verified resellers provide new Coldcard wallets in tamper-evident bags. Therefore, it is always recommended to buy it directly from the Coinkite Store. 

Coldcard Review: Customer Support

You can write to them at [email protected] In addition, they also have an active Telegram community. 

Conclusion

Coldcard wallets are one of the best affordable bitcoin hardware wallets present in the market. They are user-friendly devices with numeric keypads. The wallets are air-gapped. Moreover, they use several measures to secure the device from various kinds of attacks. Though the wallet only supports Bitcoin and Bitcoin Testnet. The Coldcard seed plate helps you to store the recovery seed phrase securely. Additionally, they also support several third-party applications. Hence if you are looking for a safe, affordable hardware wallet and use it only for Bitcoin or Bitcoin testnet, you can go ahead with Coldcard. 

Coldcard Review: FAQ

What coins does Coldcard support?

Coldcard supports Bitcoin and Bitcoin Testnet.

Is Coldcard hard to use?

Coldcard is an easy-to-use beginner-friendly wallet. They have a full-sized numeric keypad to enter the pin quickly. Additionally, they provide proper documentation which can be used to get started with the wallet. 

Which third-party apps does Coldcard support?

Coldcard supports several third-party apps such as Electrum, Casa, BlueWallet, 
Sparrow, Specter-Desktop, Wasabi wallet, Fully Noded, Unchained capital, and more.

Does coldcard offer a secondary wallet?

Earlier coldcard wallets offered secondary wallets with similar features as the main wallet but different PINs. However, due to hardware limitations, now they do not provide a secondary wallet.

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