COLDCARD Mk4

Coldcard Mk4 Overview

Initial Setup: PIN and Anti-Phishing Words

1. Prepare a piece of paper and a pen.
2. Connect the Mk4 to a power source (USB-C cable) and insert the MicroSD card.
3. Once the device is powered up for the first time, the screen will display a message regarding Coldcard's Terms of Sale and Use. Navigate down, then press ✓ to continue.
4. Next, a 12-digit number will be displayed on the screen. Check this number against the one on the tamper-evident bag and the additional copy of the bag number that was included in the tamper-evident bag to ensure the device has not been tampered with. If the numbers do not match, contact Coinkite support immediately before proceeding. Otherwise, press ✓ to continue.

1. Select Choose PIN Code.
2. Navigate down as you read the instructions to proceed to the next step.

1. On the Mk4, create and enter the PIN prefix (must be 2 to 6 characters long) and write it down, then press ✓ to continue.
2. Write down the two words displayed at the screen. These are the anti-phishing words. Press ✓ to continue.

1. Create and enter the PIN suffix (or rest of PIN, must be 2 to 6 characters long) and write it down. Press ✓ to continue.
2. Reenter your PIN prefix. Press ✓ to continue.

1. Check whether the anti-phishing words are the same with the one you wrote on step 8. Press ✓ to continue.
2. Reenter your PIN suffix (or rest of PIN). Press ✓ to continue.

1. Your Mk4's PIN and anti-phishing words are now successfully created and stored by the device.

Setting up your Wallet

• Creating a new wallet (standard)
• Creating a new wallet with dice rolls
• Importing a wallet

Creating a new wallet (standard)

1. Select New Wallet (or New Seed Words) > Select 12 Word or 24 Word (default) depending on your preference.

1. The device will generate 12 or 24 words as your seedphrase based on your choice. Navigate down as you carefully write down each word in the correct order. Then, press ✓ to continue.

Back up your mnemonic phraseDiscover best practices for safeguarding your Bitcoin wallet

1. The device will ask you to verify your seedphrase by asking the in a random order (for example, Word 1 is?, then Word 5 is?, then Word 12 is?, and so on) and there will be three word choices for each question. Refer to the note from Step 2 and choose the words correctly (by pressing 1, 2 or 3, whichever corresponds to the correct word) to complete the wallet creation.

1. Mk4 will then ask whether you want to Enable NFC/Tap or not. For now, select ✕ for this option. This can be changed in the settings in the future.
2. Finally, Mk4 will also if you want to disable the USB Port (which can be used for non-airgapped data transfer). For now, select ✓ for this option. This can be changed in the settings in the future.
3. The screen will now display the main menu with Ready to Sign at the top. This marks the completion of the wallet creation process.

Creating a new wallet with dice roll

1. Select New Wallet (or New Seed Words) > Select 12 Word Dice Roll or 24 Word Dice Roll depending on your preference.
2. You will be asked to enter the results of your dice rolls. Each dice roll adds randomness to the wallet creation process, ensuring that your seedphrase is generated in a fully secure and unpredictable way. The minimum number of rolls are 50 for 12-word seedphrase and 99 for 24-word seedphrase. Press ✓ after you have input at least 99 dice roll values.

1. The device will generate 12 or 24 words as your seedphrase based on your choice. Navigate down as you carefully write down each word in the correct order. Then, press ✓ to continue.
2. The device will ask you to verify your seedphrase by asking the in a random order (for example, Word 1 is?, then Word 5 is?, then Word 12 is?, and so on) and there will be three word choices for each question. Refer to the note from Step 3 and choose the words correctly (by pressing 1, 2 or 3, whichever corresponds to the correct word) to complete the wallet creation.

1. Mk4 will then ask whether you want to Enable NFC/Tap or not. For now, select ✕ for this option. This can be changed in the settings in the future.
2. Finally, Mk4 will also if you want to disable the USB Port (which can be used for non-airgapped data transfer). For now, select ✓ for this option. This can be changed in the settings in the future.
3. The screen will now display the main menu with Ready to Sign at the top. This marks the completion of the wallet creation process.

Importing a wallet

1. Select Import Existing.
2. Select 24 Words, 18 Words or 12 Words, depending on your seedphrase's word count.

1. Coldcard Mk4 will then ask you what each word is in consecutive order. For each word, navigate down or up until you find the write prefix for each word. The device will narrow down the possibilities until you can find the correct word. Do this for the rest of the other words.
2. For the final word, Coldcard Mk4 will display only a limited amount of possible words. If there are no matches, you may have input the words incorrectly. Otherwise, select the word that matches the one on your seedphrase.

1. Mk4 will then ask whether you want to Enable NFC/Tap or not. For now, select ✕ for this option. This can be changed in the settings in the future.
2. Finally, Mk4 will also if you want to disable the USB Port (which can be used for non-airgapped data transfer). For now, select ✓ for this option. This can be changed in the settings in the future.
3. The screen will now display the main menu with Ready to Sign at the top. This marks the completion of the wallet creation process.

Setting up your passphrase

1. Go to Passphrase.
2. Navigate down to read the description about passphrase, then press ✓ to proceed.
3. Select Edit Phrase.

1. Input your passphrase:
   • Press 1 (letters), 2 (numbers) or 3 (symbols) to select the character type.
   • Press 4 to swap between lowercase and uppercase letters (can only be used when inputting letters).
   • Navigate using ^ or ˅ to select the character for your passphrase.
   • Navigate using < or > to move between characters. You can also use > to add spaces.
   • Press ✕ to delete the characters.
   • Press ✓ when you have finished editing the passphrase.
2. Additionally, the other options have the following functionalities:
   • The Add Word or Add Numbers can be used to append letters/numbers to the passphrase you are currently editing.
   • Press Clear ALL to reset the passphrase you are currently editing.
   • Press CANCEL to go back to the main menu.
3. Write down your passphrase as a backup.
4. Press APPLY to access the wallet with the passphrase you have just set.
5. Mk4 will then display a 8-character long master key fingerprint. This can be regarded as the "ID" of the wallet. Write down this fingerprint and press ✓ to proceed.

1. Now, the wallet will display the main menu of the wallet with the passphrase that you have input.
2. It's important to note that a wallet will not tell you that you have input the incorrect passphrase, because each passphrase corresponds to each own wallet with a unique identity (master key fingerprint). Therefore, it’s a good practice to re-enter the same passphrase and check whether it produces the same wallet fingerprint, ensuring that you’ve entered it correctly. To do that, perform Steps 11 to 14.
3. On the main menu, select Restore Master, then press ✓. You are now back in the main menu of the wallet with the blank passphrase.

1. Go to Passphrase again, then press ✓ to proceed.
2. Reinput the passphrase that you have written down on Step 6, then press APPLY.
3. Check the 8-character long master key fingerprint against the one you have written down on Step 8. If both fingerprints does not match, you may have typed mismatched characters. You can select a new passphrase instead and repeat the process from Step 1. But if both fingerprints match, it means that you have input the passphrase correctly.
4. The wallet with your chosen passphrase is ready to be used.

Exporting the Wallet to Sparrow

1. Ensure that you have a MicroSD card inserted into the Mk4.
2. Perform the "Setting up your passphrase" steps on the wallet with the passphrase that you want to export. If you want to export the wallet with the blank passphrase, you can skip this step.
3. Go to Advanced/Tools > Choose Export Wallet > Select Generic JSON > Scroll down as you read the instructions, then press ✓.

1. Mk4 now has created a file with a .json format in the MicroSD card.

1. Remove the MicroSD card from the Coldcard and insert it into the device where Sparrow Wallet is installed.
2. Open Sparrow Wallet.
3. Click on File

1. Select the Script Type.

1. On the Keystore section, select Airgapped Hardware Wallet.

1. Look for Coldcard and click Import File....

1. Select the file that was created in Step 4 (the one with the .json format).

1. On the Mk4, return to the main menu and navigate to Advanced/Tools > View Identity. Ensure that the fingerprint displayed on the Mk4's screen matches the one on Sparrow Wallet (the Master fingerprint on the Keystore section)
2. Click the Apply button on the bottom right corner.

1. Optionally, you can also add a password for the exported wallet. This password is required each time you open the Sparrow Wallet application to access the wallet. If you forget the password in the future, you can simply repeat Steps 1-13 and choose a new password.

1. The wallet is now successfully exported and ready to be used.

Receiving bitcoin

1. Open Sparrow Wallet.
2. Select Open Wallet > Choose the wallet file to which you want to receive bitcoin > Enter the password associated with that wallet.

1. On Sparrow's interface, click on the Receive tab on the left side of the interface.

1. An address along with a QR code will appear at the top. You can copy and paste the address or scan the QR code using the wallet you’ll use to send bitcoin to Sparrow Wallet. Optionally, you can type in a label for the bitcoin you receive.

1. After you send the bitcoins, on Sparrow's interface, click on the Transactions tab on the left side of the interface. You’ll see a new entry at the top of the transaction history, which corresponds to the transaction you just made.

1. You can also navigate on the UTXOs tab on the left side of the interface to see the bitcoin you just received.

Sending bitcoin

1. Insert the MicroSD card into the device where your Sparrow Wallet is installed.
2. Open Sparrow Wallet.
3. Select Open Wallet > Choose the wallet file you want to use to send bitcoins with > Enter the password associated with that wallet.

1. On Sparrow's interface, click on the Send tab on the left side of the interface.

1. On the Pay to tab, enter the address you want to send the bitcoins to.
2. Add a label for the transaction.
3. Enter the amount of bitcoins you want to send.
4. Enter the fee by toggling the Range or directly input a number into the Fee part.

1. On the bottom right corner, click Create Transaction.

1. You will be brought into a new transaction tab whose name is the label you input on Step 6. Click Finalize Transaction for Signing.

1. Click Save Transaction and save the transaction in the MicroSD card. Rename the file if necessary. This step will save the transaction as a PSBT file.

1. Remove the MicroSD card and insert it into your Coldcard Mk4.
2. Turn on your Mk4 by connecting it to a power source.
3. Input your PIN.
4. Go to Passphrase and input the passphrase of the wallet you want to use to send the bitcoins with. If you want to use the wallet with the blank passphrase, skip this step.
5. Ensure the master key fingerprint is the same with the one on your Sparrow Wallet. You can check this on Sparrow Wallet's Settings tab on the left side of the interface. Then, press ✓ on your Mk4 to proceed. This will take you to the main menu.
6. On Mk4's main menu, select Ready to Sign. The screen will display an OKAY TO SEND? message. Ensure the amount of the bitcoins you want to send and the receiving address are all correct. Press ✓ to confirm or ✕ to cancel.
7. If there are multiple PSBT files to choose from, Mk4 will display Choose PSBT file to be signed message. Press ✓ to continue. Then, select the PSBT file you want to sign by navigating down or up. Perform Step 17 on that transaction.

1. Mk4 will now display the PSBT Signed message along with the name of the file of the signed PSBT. Press ✓ to continue.
2. Remove the MicroSD card from the Coldcard and insert it into the device where Sparrow Wallet is installed.
3. On Sparrow Wallet, click Load Transaction.

1. Select the file with the same name as the one created on Step 19.

1. Click Broadcast Transaction.

1. Your transaction has been broadcast and it is being processed. You can go to the Transactions tab to view the confirmation status of your transaction.

Firmware Upgrade

Checking your Firmware Version

1. Turn on your Mk4 by connecting it to a power source.
2. Input your PIN.
3. Go to Advanced/Tools > Select Upgrade Firmware > Select Show Version.

Upgrading your Firmware

1. Insert the MicroSD card into your laptop/PC.
2. Go to Coinkite's website and download the latest firmware to your MicroSD card (The red button right of the Mk4 image with the version number on it).

1. Remove the MicroSD card and insert it into your Mk4.
2. Turn on your Mk4 by connecting it to a power source.
3. Input your PIN.
4. Go to Advanced/Tools > Select Upgrade Firmware > Select From MicroSD > Scroll down as you read the instructions then press ✓.

1. Select the .dfu file that you downloaded in Step 2.
2. Coldcard Mk4 will display an Install this new firmware? message. Scroll down as you read the instructions then press ✓.

1. Wait for the Mk4 to finish installing the new firmware. Do not disconnect the power source during the installation.
2. Upon completion, Mk4 will restart itself. You may enter your PIN and perform the "Checking your Firmware Version" steps to check whether the firmware has been upgraded or not.

Advanced Features

Change your PIN

1. Prepare a pen and a piece of paper.
2. Turn on your Mk4 by connecting it to a power source.
3. Input your PIN.
4. Go to Settings > Select Login Settings > Select Change Main PIN
5. Navigate down as you read the message, then press ✓ to proceed.

1. Input your old PIN.
2. Input your new PIN prefix (must be 2 to 6 characters long) and write it down.
3. Mk4 will now display two new anti-phishing words, write them down, then press ✓ to proceed.
4. Input your new PIN suffix (or rest of PIN, must be 2 to 6 characters long) and write it down.

1. Reenter your new PIN prefix.
2. Check whether the anti-phishing words match the one you wrote in Step 8.
3. Reenter your new PIN suffix (or rest of PIN).

1. Your PIN has successfully been changed.

Trick PINs - Add New Trick

1. Prepare a pen and a piece of paper.
2. Turn on your Mk4 by connecting it to a power source.
3. Input your PIN.
4. Go to Settings > Select Login Settings > Select Trick PINs > Select Add New Trick.

1. Input your trick PIN prefix (must be 2 to 6 characters long) and write it down.
2. Mk4 will now display two new anti-phishing words, write them down, then press ✓ to proceed.
3. Input your trick PIN suffix (or rest of PIN, must be 2 to 6 characters long) and write it down.

1. Navigate down or up to select the action you want to pair with the trick PIN you just created. The list of actions are:
   • Brick Self, when selected, your Mk4's chips will be destroyed after the PIN is entered, making your Mk4 to be unusable permanently.
   • Wipe Seed, you can choose between the following actions:
     • Wipe & Reboot: The seed is wiped and Coldcard will reboot after the PIN is entered.
     • Silent Wipe: The seed is wiped silently, however Coldcard will act as if the PIN was entered incorrectly.
     • Wipe -> Wallet: The seed is wiped silently, and the Coldcard will take you into a duress wallet.
   • Duress Wallet, when selected, your Mk4 will lead to a duress wallet after the PIN is entered.
   • Login Countdown, you can choose between the folowing actions:
     • Wipe & Countdown: The seed is immediately wiped, then Mk4 will begin displaying a countdown.
     • Countdown & Brick: The countdown begins and Mk4 will brick itself after the time runs out.
     • Just Countdown: Mk4 will begin the countdown and will reboot itself after the time runs out.
   • Look Blank, when selected, after the trick PIN is entered, the Coldcard act as if the seedphrase is wiped, but it is in fact still in memory.
   • Just Reboot, when selected, Coldcard will reboot itself after the trick PIN is entered.
   • Delta Mode, This advanced feature is meant for experienced users and is designed to protect against serious threats, such as coercion by someone with insider knowledge. When Delta Mode is activated, the COLDCARD appears to open the real wallet, allowing the attacker to browse and confirm that it looks genuine. However, it secretly blocks all transaction signing, so no bitcoin can be sent. It also disables access to the seed phrase, and any attempt to view it will erase it completely. To make the fake wallet look more convincing, the Trick PIN used for Delta Mode must start with the same numbers as the real PIN (so it shows the same anti-phishing words) but end differently.
   • Policy Unlock, when selected, Single Signer Spending Policy (SSSP) will be disable after the trick PIN is entered.
   • Policy Unlock & Wipe, when selected, it pretends to disable SSSP but it will wipe the seedphrase in the process.
2. After you have selected the action you want to pair with the trick PIN, confirm your choice by pressing ✓. Your trick PIN is successfully configured.
3. In the Settings > Login Settings > Trick PINs, you can see the list of trick PINs you have created and the actions paired with it. You can choose to reconfigure the trick PINs and the actions paired with it. You can also hide or delete it by selecting the PIN then select Hide Trick or Delete Trick.

Trick PINs - Add If Wrong

1. Turn on your Mk4 by connecting it to a power source.
2. Input your PIN.
3. Go to Settings > Select Login Settings > Select Trick PINs > Select Add If Wrong.

1. Mk4 will display a message regarding this setting. Navigate down as you read through the explanation, then press ✓ to proceed.
2. Input the number of wrong attempts required to trigger the action. Note: The maximum attempt count is 12. This is because Mk4 is designed such that when the incorrect PIN is entered 13 times, the device will brick itself, making it unusable permanently. After you input the number, press ✓ to continue.
3. Navigate up or down to select the action. The actions available are as follows:
   • Wipe, Stop: The seedphrase is erased and the device shows “Seed is wiped, Stop.”
   • Wipe & Reboot: The seedphrase is erased and the device restarts without any message.
   • Silent Wipe: The seedphrase is erased quietly and the device behaves like a wrong-PIN attempt (no obvious wipe message).
   • Brick Self: The device is permanently disabled and only shows “Bricked.”
   • Last Chance: The seedphrase is erased but you get one final PIN attempt; enter the wrong PIN again and the device will be bricked.
   • Just Reboot: The device simply restarts and nothing else changes. Choose the action you want to apply and press ✓ to proceed

1. You will be brought back to the Settings > Login Settings > Trick PINs directory. Under the Trick PINs:, you will find the list of trick pins along with WRONG PIN action. You can also hide or delete it by selecting the PIN then select Hide Trick or Delete Trick.

Conclusion