Coldcard FAQ

When will it ship?

You can pre-order your Coldcard Wallet today, but the first build has almost sold out. Early bird purchases will be shipped in August 2018.

Is it a bare board?

No, we have moved to a clear plastic case. It is ultrasonically welded and cannot be taken apart easily.

How many seed words does it use?

Coldcard always generates 24-word BIP39 seed phrases. It can also import 12, 18 and 24-word, unencrypted, BIP39 seed phrases that other wallets may have created.

Can I have multiple wallets in each Coldcard?

There is a primary and secondary wallet. Each would typically have it's own master key from different seeds. In addition, we have a "duress" wallet for each of those wallets, but they are derived from the correspond wallet's seed words and are not independent.

Can I change my PIN?

Yes, the PIN can be changed at any time and is independent of the funds being held.

What blockchains do you support?

Bitcoin and Bitcoin Testnet are recommended. We support Litecoin, but there may not yet be a desktop wallet to accompany that. Coldcard does not support altcoins at this time.

Coldcard requires a desktop or mobile wallet to manage your coins and speak to the public blockchain. Although we can add support for other coins when they have suitable wallet support.

Why does it have a MicroSD slot?

  • The Coldcard can backup the seed into an encrypted file.
  • New transactions to be signed, can be imported from the card.
  • Public key data (xpub, receive addresses) can be written onto the card.
  • Firmware upgrades can be done by copying the new firmware file onto a card.
  • A skeleton Electrum wallet can be created on the card which allows Electrum to "pair" with the Coldcard, without it ever connecting to a USB port.

How do I connect to a computer?

Use the USB port at the top of the Coldcard. You must provide a standard MicroUSB cable suitable for your computer.

Coldcard does enable the USB port until a correct PIN code is entered so it will not appear on your computer until the PIN is entered.

There is no need to use the USB port, except for power, during seed setup and when using the MicroSD card slot itself. We use the Coldcard with USB battery packs routinuely, although some battery packs do not correctly detect the Coldcard beause it uses very little power. They may power down because it appears that nothing is connected. Most simple battery packs and wall chargers are fine.

What is PSBT?

PSBT is an emerging standard for "Partially Signed Bitcoin Transactions" and is described by BIP 174.

Coldcard is the first "PSBT Native" hardware wallet. It uses PSBT internally, and should be able to sign most PSBT files generated by conforming software. For completed transactions, we can output either a PSBT (with the new signatures added) or a finalized Bitcoin transaction, ready to send.

How do I backup?

Insert a MicroSD card, and go to Advanced > Backups > Backup System.

You'll be shown a 12-word password to be recorded, and have to pass a short quiz to prove you did that.

Then the file is saved as an AES-encrypted 7Z file on the MicroSD card.

We suggest keeping the password and file in different locations. The backup file is useless without the 12-word passphrase. Each backup will have a different backup phrase, and it has no relationship with the wallet seed words.

Backups can also be verified (checked for completeness) from the menu system.

Read more in our docs about backups.