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How to sign transactions using a Coldcard
How to sign transactions using a Coldcard

Steps to signing and authorizing vault transactions with a paired Coldcard.

J
Written by Jake Morr
Updated over 6 months ago

Here’s how to sign a transaction using a Coldcard hardware device.


Open Web Application

  • After initiating your send transaction within the Theya app, you will be prompted to sign the transaction using the key(s) paired with your vault.

    • Two signatures for multisig

    • One signature for single-sig

  • Click ‘Sign with [Device Name]’ and signing instructions will be sent via email to you (or your cosigner).

  • Ensure your Coldcard hardware device(s) are ready to sign a transaction.

    • For air-gapped signing, you will need your microSD card and adapter, as well as a power-only USB cable.

    • If connecting via USB (USB virtual disk mode), you will need a USB cable compatible with the device.

  • Click the 'Sign Transaction' link provided in the email to open the Theya web application.


Signing Process

  • Insert your SD card into your computer.

  • Download the PSBT (Partially Signed Bitcoin Transaction) from the web application and save to your SD card.

  • Insert your SD card into your Coldcard.

  • On your device, navigate to Ready To Sign > Chose File And Sign.

    • The file name will be displayed on the Theya web application.

  • Once signing is complete, insert the SD card back into your computer.

  • Locate the signed PSBT on your SD card and import into the web application.

    • The file name will be displayed on the Theya web application.

  • The Theya app will now show that the signature has been completed.

If conducting a multisig vault transaction, the Theya app will display progress on the signature process. After signing with you first key, you can repeat the process for the second key.

  • Once all necessary keys have signed, you can broadcast the transaction to the network. Check the confirmation status using the Mempool.Space block explorer link provided or transaction history on your Theya vault homepage.

    • Your vault balance will update after 3+ confirmations.


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