Master Seed

What are Seeds?

Your Bitcoin seed is the root of your wallet, generating all your private keys. Typically expressed as a set of seed words under the BIP-39 standard, these words hold all the information needed to recreate your entire wallet (past and future addresses) on any compatible software. This makes your seed a true superpower, granting you vendor-agnostic control.

With just your seed words, you can restore your Bitcoin across nearly any wallet, free from reliance on custodial entities, centralized systems, or closed source "trust me" stacks. This sovereignty aligns with Bitcoin’s decentralized ethos, empowering you to securely and independently manage your funds with unmatched freedom.

What is the Master Seed?

The Master Seed is the core secret for your COLDCARD^®. Not only is this seed used to derive all of your Bitcoin addresses, but it is also the source of creation for many other secrets on the COLDCARD. The Master Seed is used to derive the following secrets:

• Bitcoin Address Private Keys
• BIP-39 Passphrase Wallets
• Duress Wallets
• BIP-85 Seeds
• BIP-85 Passwords

This makes creation, backup, and protection of your Master Seed extremely critical. Anyone with access to your unencrypted Master Seed can steal your funds and derive any of the other mentioned secrets. That could be a person that finds your seed words written down, or a remote attacker that simply generated for themselves a Master Seed with weak entropy.

In the Create a New Master Seed section we will guide you through securely generating a new Master Seed on a COLDCARD using one of three entropy sources.

If you already have a BIP-39 based wallet, other private key material, or intend to clone an existing COLDCARD, you can jump to the section Import an Existing Seed to learn more.

Create a New Master Seed

You can create a new Master Seed (12 or 24 words) directly on an empty COLDCARD. That can be either a new device, or one that has had the Master Seed destroyed. To ensure the seed's randomness, you can choose from three entropy sources: the COLDCARD's built-in True Random Number Generators (TRNGs), physical dice rolls, or a combination of the two.

Seed Word Generation Method Trade Offs

COLDCARD TRNGs Only: This method involves the most trust, as it is using the hardware of the COLDCARD to generate entropy (randomness) for your seed. This method is not reproducible, is low risk to users, and protects the user from any possible mistakes.

COLDCARD TRNGs + Dice: This method can be considered the middle ground as far as trust is concerned. It still uses the COLDCARD hardware to generate random data, but now adds in entropy that you can create via dice rolls. This method is not reproducible, and is low risk to users. Although not reproducible and involving some trust, it is minimized and users cannot produce worse entropy than using the COLDCARD's TRNGs only method.

Dice Only: This method can remove all trust in the COLDCARD's hardware, as all of your entropy is produced by your dice rolls. This method is fully reproducible using the Verifying Dice Roll Math document. However, if warnings are not heeded, it is possible to generate seeds that will be stolen immediately.

Choose from the dropdowns below to guide you through creating a new Master Seed using your preferred entropy source.

Create a New Master Seed Using TRNGs Only or TRNGs + Dice Rolls

TRNGs Only or TRNGs + Dice Rolls

1. Select New Seed Words from the Main Menu of an empty COLDCARD.

   

2. Choose 12 Words or 24 Words to create a seed of that length.

3. The COLDCARD will create the seed using only the device's TRNGs, and present the words on the screen. If you are satisfied trusting the TRNGs of the device, skip to Step 8.

   

   • You can view the words as a QR code by pressing 1/QR.

     

4. To add dice roll entropy to the current seed, tap 4. You'll be shown the total number of rolls and the current entropy represented as an ASCII string.

   

5. Roll your 6-sided die and enter the number rolled on the COLDCARD. You'll see the seed change with each dice roll. For more info see Verifying Dice Roll Math.

   

6. Repeat Step 5 as many times as you'd like (1 roll adds 2.585 bits of entropy), and hit ✔/ENTER when finished.

7. The COLDCARD will display the new seed words created using both the TRNGs and dice rolls.

   

   • Use 1/QR to view the seed words as a QR code.

     

8. Write down the seed words to use as a backup! A card was included with your COLDCARD that you can use for recording your words.

   You MUST keep a backup of your Master Seed!

   Without a backup of your Master Seed, you will lose access to your Bitcoin if anything happens to your COLDCARD. Loss, theft, forgotten PIN, or hardware failure are just some of the ways you may lose access to your COLDCARD.

   The best way to backup all of your COLDCARD info, including the Master Seed, is to use the built-in encrypted backup.

9. Press ✔/ENTER to begin the test of your backup.

10. You'll be given multiple choices for a random seed word. Refer to your backup and choose the right word.

    

11. Repeat until you have successfully picked each seed word.

    • At any point you can tap ✔/ENTER to see the words again.

    • If you need, you can give up on these words and create new ones. Hit X/CANCEL, read the warning, then press ✔/ENTER. Go back to Step 2 and follow along from there.

12. Once you've successfully passed the test, the new Master Seed will be applied to your COLDCARD and you will get some welcome info. Press ✔/ENTER when you're ready to use your COLDCARD.

    Be sure to store the written backup of your seed words safely, and/or create an Encrypted Backup at this point.

    

Create a New Master Seed Using Dice Rolls Only

Dice Rolls Only

1. Go to: New Seed Words > Advanced from the Main Menu of an empty COLDCARD.

   

2. Choose the length of the seed you are creating: 12 Word Dice Roll or 24 Word Dice Roll.

3. Roll a 6-sided die and enter the number rolled on the COLDCARD. You'll see the seed change with each dice roll. For more info see Verifying Dice Roll Math.

   

4. Repeat Step 3 until you have reached a total of 50 rolls for a 12 word seed (128 bits of entropy), or 99 rolls for a 24 word seed (256 bits of entropy), and enter each number rolled into the COLDCARD.

   No Shortcuts on Dice Rolls!

   The strength of your Master Seed depends on the minimum number of dice rolls being met, and that the die is actually rolled each time. You cannot fabricate dice rolls without compromising security, possibly resulting in stolen funds!

   The only way to speed up this process is to use multiple dice to limit rolls. You can get a set of 100 small dice at the Coinkite Store.

5. When all your rolls are entered, press ✔/ENTER.

   • If you have not entered the minimum number of rolls required for your seed length, you will receive an error. Use ✔/ENTER to add more dice rolls, or X/CANCEL to abort.

     

   • You can also trigger an error if the COLDCARD believes your rolls were not random enough. In this case you'll have to hit ✔/ENTER to start over from Step 2.

     

6. The COLDCARD will show the seed words created from the dice rolls you entered on-screen.

   

   • If you would like to go back and add more dice rolls, press 4. Add your dice rolls, and press ✔/ENTER to see your new seed words.

   • To view the seed words as a QR code, use 1/QR.

     

7. Write down the seed words to keep as a backup! Your COLDCARD came with a card that you can use to write your words on.

   You MUST keep a backup of your Master Seed!

   Without a backup of your Master Seed, you will lose access to your Bitcoin if anything happens to your COLDCARD. Loss, theft, forgotten PIN, or hardware failure are just some of the ways you may lose access to your COLDCARD.

   The best way to backup all of your COLDCARD info, including the Master Seed, is to use the built-in encrypted backup.

8. Once you have the words backed up, press ✔/ENTER to begin the test of your backup.

9. You'll be asked to select your seed words in random order from multiple choices. Refer to your backup and choose the right words.

   

10. Repeat until you have successfully picked each seed word.

    • At any point you can tap ✔/ENTER to see the words again.

    • If you need, you can give up on these words and create new ones. Hit X/CANCEL, read the warning, then press ✔/ENTER. Go back to Step 2 and follow along from there.

11. Once you've successfully passed the test, the new Master Seed will be applied to your COLDCARD and you will get some welcome info. Press ✔/ENTER when you're ready to use your COLDCARD.

    Be sure to store the written backup of your seed words safely, and/or create an Encrypted Backup at this point.

    

Import an Existing Seed

You can import an existing seed to use as your COLDCARD's Master Seed. The imported seed can be seed words, raw XPRV, a COLDCARD backup file, a clone of another COLDCARD, or a combination of seeds previously split with Seed XOR.

To import an existing seed, you must start with an empty COLDCARD. That can be either a new device, or one that has had the Master Seed destroyed. Then select Import Existing from the Main Menu.

Once on the Import Existing Menu, choose from one of the options listed below. Use the dropdowns, or provided links, to learn more about each import method.

12/18/24 Words

Choose the number of words (12, 18, or 24) in the BIP-39 (English only) seed you would like to import. The final word is a checksum value that verifies the other words.

Steps to Import Seed Words

1. From the Import Existing Menu, select your seed length: 12 Words, 18 Words, or 24 Words.

   

2. Enter your seed words in the correct order:

   • COLDCARD Q: Use the keyboard to type each of your seed words. When you've typed enough characters the words will auto-complete for you. For shorter words, you may have to press ENTER to move on.

     If you make any mistakes, use the ⌫ key to go back a single character or a whole word. Tap CANCEL if you need to quit.

     • To scan a QR code of the seed words, hit QR.

     

   • COLDCARD Mk4: Scroll up and down to select each letter of each word individually until all words have been entered. Use 5 and 8 to scroll through your choices, which reduce with each letter you add. Your current word count is on the top right corner of the screen.

     Use the X key to go back a character or word, press repeatedly to remove all words and start over.

     

3. Once you enter the final word, press ✔/ENTER and the seed will be applied to your COLDCARD.

   

Scan QR Code (Q only)

Starts the QR scanner for reading a QR code containing an XPRV or seed words.

For instructions, go to: Scan Seeds.

Restore Backup

Import a backup file from another COLDCARD. You will need the backup file (7z) on the MicroSD card, and you must enter the 12-word password that was provided at the time the backup was created.

To learn more, see: Restore Backup as Master Seed.

Clone Coldcard

Starts a secure process to clone an existing COLDCARD's data to this COLDCARD. You will need a MicroSD card, the source COLDCARD (to be cloned), and the empty COLDCARD all physically present to complete the procedure.

For details, head to: Clone or Migrate a COLDCARD.

Import XPRV

To import an XPRV, you must provide a cleartext file via MicroSD, Virtual Disk, NFC, or QR code (Q only) with a BIP-32 base58-serialized extended master private key. It should start with xprv and be on a single line of a text file. The rest of the file is ignored.

There is no encryption when importing an XPRV, therefore it is considered hazardous and is only recommended for testing purposes!

Steps to Import XPRV

1. Prepare the XPRV by putting it on an SD card, the COLDCARD's Virtual Disk, or in a QR code.

   • If using an SD card, insert it in the COLDCARD after transferring the XPRV.

2. Select Import XPRV from the Import Existing Menu.

   

   • On the Mk4, if the Virtual Disk and NFC are not enabled, the COLDCARD will list all files on the SD card that contain an XPRV. Pick the file and hit ✔ to apply the XPRV as the Master Seed of the COLDCARD. You can move on to Step 4 now.

3. On the Q, and the MK4 when the Virtual Disk is enabled, you will have to choose where to import the XPRV from:

   

   • 1/B: Import the XPRV from an SD card (on the Q: use 1 for Slot A, or B for Slot B). Select the file and press ✔/ENTER to apply the XPRV as the Master Seed.

   • 2: Use the Virtual Disk (if enabled) storage for the XPRV. Pick the filename from a list of candidate files found on the Virtual Disk. Once selected, tap ✔/ENTER and the XPRV will be applied as the Master Seed.

   • 3/NFC: Transfer the XPRV via NFC (if enabled) to apply as the Master Seed. Tap an NFC-enabled device to the COLDCARD to transfer the XPRV, and apply it as the Master Seed.

   • QR (Q Only): Starts the QR scanner to import the XPRV from a QR code. Scan a QR code containing an XPRV and it will be applied to the COLDCARD as its Master Seed.

4. After successfully transferring and applying the XPRV, you'll be presented a welcome message. To start using the COLDCARD with the new Master Seed, press ✔/ENTER.

   

Tapsigner Backup

Uses a TAPSIGNER^® backup file to import the seed from the TAPSIGNER as the Master Seed on the COLDCARD.

Steps to Import Tapsigner Backup

Import From TAPSIGNER to COLDCARD

To import your TAPSIGNER backup (XPRV) to your COLDCARD you must have two things:

• Backup Password: A 32-character hexadecimal string located on the back of the card under the Backup Password header and printed along the edges of the card.

  

• Encrypted Backup File: You can obtain the .aes file during the TAPSIGNER initial setup (save it for later), or by having the TAPSIGNER card as well as the correct pin.

  From the command-line, you can use cktap proto to get the backup file. Type cktap backup which saves the card's XPRV into an AES-128-CTR encrypted file with the current date.

If you don't wish to use the XPRV as your Master Seed and prefer a "one time use", you can import it as a Temporary Seed — meaning you do not need to Destroy Seed first. To do this, go to: Advanced Tools > Temporary Seed > Tapsigner Backup. This way the Master Seed is preserved and TAPSIGNER Backup will only last until the device is powered off, with an option to save it in the Seed Vault.

1. To begin, select Tapsigner Backup from the Import Existing Menu.

   

   • On the Mk4, if the Virtual Disk and NFC are not enabled, the COLDCARD will list all the TAPSIGNER backup files now. You can skip to Step 3.

     

2. On the Q, and the MK4 when the Virtual Disk is enabled, you will have to choose where to import the XPRV from:

   

   • 1/B: Import from an SD card (on the Q: use 1 for Slot A, or B for Slot B).
   • 2: Use the Virtual Disk (if enabled) storage for the TAPSIGNER backup file.
   • 3/NFC: Transfer the backup via NFC (if enabled).
   • QR (Q Only): Starts the QR scanner to import the backup from a QR code.

3. Next choose the .aes file, tap the NFC-enabled device with the backup, or scan the QR code.

   

4. Have your TAPSIGNER available to retrieve the Backup Password, and press ✔/ENTER.

   

5. Enter the Backup Password from the TAPSIGNER into the COLDCARD.

   

6. Once entered, your COLDCARD will generate the XPRV and store it safely. You can now export the public key and view the funds on any Compatitble Software Wallet.

Extract TAPSIGNER XPRV (Raw)

The TAPSIGNER can generate a backup file of its master private key. This file is protected by a factory-programmed password, which can be found on the back of the card.

To verify that your backup works correctly or to recover the private key, you can run the below command on the command line. Replace PASSWORD with your TAPSIGNER's backup password, and FILE with the path to your backup file.

    openssl aes-128-ctr -iv 0 -K PASSWORD -in FILE.aes

If everything works correctly, you should be able to see the master private key printed out as simple text. The key starts with the prefix xprv.

For best security, we recommend that you only run the above tools on a secure machine, and immediately remove the backup file afterwards.

These steps will expose your private key to the local machine. Use at your own risk!

Nunchuk Recovery

1. On the main screen select the Keys tab.

   

2. Click on the '+' at the top of the screen.

   

3. Pick TAPSIGNER from the available options.

   

4. Select Recover TAPSIGNER key from backup.

   

5. Hit Continue.

   

6. Select the .aes file from your phone's internal storage or a cloud location, and click Done.

   

7. Input the Backup Password from the back of the TAPSIGNER, and tap Continue.

   

8. Name your recovery key, and hit Continue.

   

9. Your TAPSIGNER key has now been recovered on Nunchuk.

   

Keep in mind that this is now a software key (hot) and no longer requires the TAPSIGNER to sign transactions.

Seed XOR

Combine seeds previously split with Seed XOR (12, 18, or 24 words) and apply to the COLDCARD as the Master Seed. You must have access to all parts of the split seed to complete the process.

Steps to Combine and Import Seed XOR Parts

If you don't wish to use the combined seed as the Master Seed and prefer a "one time use", you can import it as a Temporary Seed — meaning you do not need to Destroy Seed first. To do this, go to: Advanced Tools > Danger Zone > Seed Functions > Seed XOR > Restore Seed XOR. This way the Master Seed is preserved and combined seed will only last until the device is powered off, with an option to save it Seed Vault.

1. First, make sure you have all the parts of your split seed. Only you know how many total parts you need (max 4), which was decided when the seed was split.

2. Select Seed XOR from the Import Existing Menu.

   

3. Read the information, and choose how many words are in each of your parts (all parts must be equal length):

   

   • ✔/ENTER: 24 words
   • 1: 12 words
   • 2: 18 words

4. On the next screen you need to enter Part A of the split seed. It doesn't matter which part you use for Part A, as the parts can be entered in any order. However, the words in each part DO need to be entered in correct order.

   • COLDCARD Q: Use the keyboard to type each of your seed words. When you've typed enough characters the words will auto-complete for you. For shorter words, you may have to press ENTER to move on.

     If you make any mistakes, use the ⌫ key to go back a single character or a whole word. Tap CANCEL if you need to quit.

     • To scan a QR code of the words, hit QR.

     

   • COLDCARD Mk4: Scroll up and down to select each letter of each word individually until all words have been entered. Use 5 and 8 to scroll through your choices, which reduce with each letter you add. Your current part and word count is on the top right corner of the screen.

     Use the X key to go back a character or word, press repeatedly to remove all words and start over.

     

5. Once you've entered the final word, press ✔/ENTER.

   

6. Hit 1 to move on to Part B, and repeat the steps for entering the seed words.

   

7. After entering the final word of Part B, tap ✔/ENTER.

   

8. The next screen will show you how many total parts you have entered, along with the final word of the seed these parts will create. If you still have parts to enter, repeat Steps 6 and 7 until all your parts have been entered.

   When all the parts have been entered, move on to Step 9.

   

9. Now that all your parts have been entered, press 2 to apply the combined seed as the Master Seed of the COLDCARD.

   

10. Tap ✔/ENTER to start using your COLDCARD with the new Master Seed.