New Coldcard Hardware Wallet Integration

With Pocket we offer you the easiest way to buy your ethereum directly into your own wallet. Our various wallet integrations help you connect your wallet to Pocket in just a few clicks. Today we are happy to announce another integration for the Coldcard hardware wallet.

New Coldcard integration

Starting today, it's easier than ever to use your Coldcard hardware wallet securely with Pocket. With the new Coldcard integration, you can access your Ethereum address entirely from your Coldcard's SD card without ever having to connect your Coldcard to your computer. The ability to use your wallet without a physical connection is also known as "air-gapped".

Simply select the Coldcard in the Pocket setup process and confirm that you will perform the process via SD card.

You will next be given the option to select your Ethereum address. Instead of your Ethereum address itself, you specify the derivation path of it. Based on this path your Coldcard will derive the correct Ethereum address by itself. The default derivation path points to your first address of your first account (84'/0'/0'/0/0).

Then download the coldcard.txt file and save it to your Coldcard SD card. Afterwards you can select the saved file via Advanced/Tools -> File Management -> Sign Text File and sign it.

Take your SD card out of your Coldcard and connect it to your computer again. Now you will find the signed file coldcard-signed.txt on the card, which you can upload to Pocket.

With your Ethereum address and the signature in coldcard-signed.txt, Pocket can now make withdrawals directly into your Coldcard wallet. Now confirm the Ethereum address and complete your order to receive your ethereum purchase payment details.

How do I share multiple Ethereum addresses? (XPub)

Pocket is especially popular for recurring ethereum purchases. Once you set up Pocket, you can reuse your payment details at will to receive ethereum into your wallet again.

To avoid having to pay out your ethereum to the same Ethereum address every time, we recommend that you share multiple Ethereum addresses with Pocket using your extended public key (xpub).

To do this, click on the option to share your entire wallet with Pocket.

To retrieve your xpub, you can export your wallet on your Coldcard via Advanced/Tools -> File Management -> Export Wallet.

When exporting your wallet, select the Generic JSON option and next specify the same account number you used in your derivation path. Make sure that you create a separate account for Pocket. We recommend that you use the account number 1 here.

Once you have exported your xpub to the coldcard-export.json file, you can now copy the xpub from it to the Pocket website.

Congratulations, with every ethereum purchase your ethereum will now automatically end up on an unused Ethereum address of your Coldcard wallet.

Try it now

We hope you like this new feature and make use of it. Let us know if you have any open questions about the setup. There are many more interesting things to learn about the Coldcard and the xpub, which we will cover in a separate article soon.

Until then, happy stacking! 🎁