At Nunchuk, we’re committed to providing you with secure and user-friendly solutions for managing your Bitcoin holdings. Today, we’re excited to announce an enhancement to our flagship service, the Honey Badger subscription plan: you can now use COLDCARD as your inheritance key hardware, in addition to TAPSIGNER.

This update also applies to our Byzantine subscription services, designed specifically for Bitcoin advisors. Both individual users and professional advisors can now leverage our advanced inheritance planning features with greater flexibility.

A Quick Recap of the Honey Badger Plan

The Honey Badger plan is an assisted 2-of-4 multisig wallet that includes an integrated inheritance planning feature. Here’s how it works:

• You hold three keys, one of which is designated as the inheritance key.
• The platform holds one key, known as the Platform Key.

This setup ensures that you’re always in control of your wallet. Even if something happens to your devices or our platform, you can recover your funds using your keys. The inheritance key allows your designated beneficiary to access your Bitcoin after a specified timelock, ensuring your legacy is secure.

Similarly, the Byzantine subscription offers these inheritance planning features to Bitcoin advisors, enabling them to provide secure and reliable inheritance solutions to their clients.

Introducing COLDCARD as an Inheritance Key Option

Previously, the inheritance key in the Honey Badger and Byzantine plans had to be a TAPSIGNER card. While TAPSIGNER offers a convenient and secure way to manage your inheritance key, we understand that users and advisors have different preferences and requirements.

With our latest update, you now have the option to use a COLDCARD hardware wallet as your inheritance key. Both COLDCARD and TAPSIGNER are produced by our trusted partner, Coinkite, one of the most reputable names in Bitcoin hardware solutions.

Why Choose COLDCARD?

Using COLDCARD as your inheritance key brings significant benefits:

1. User-Generated Backup Password: Unlike TAPSIGNER, where the Backup Password is pre-generated at the factory, COLDCARD allows you to generate your Backup Password on demand. This adds an extra layer of personalization and security.
2. Human-Friendly Backup Password: COLDCARD’s Backup Password is a 12-word BIP39 mnemonic phrase, making it easier to memorize, write down, and share securely with your beneficiary. In contrast, TAPSIGNER uses a 32-character hexadecimal string, which can be more challenging to handle.
3. Flexible Interaction Methods: The COLDCARD Mk4 and COLDCARD Q support multiple interaction methods, including NFC, USB, microSD card, and QR codes (with the COLDCARD Q). This provides you with a variety of options to suit your preferences.

How COLDCARD Enhances the Inheritance Process

When you set up your Honey Badger or Byzantine wallet with COLDCARD as the inheritance key, here’s how the process ensures maximum security:

• Encryption of Private Key Backup: COLDCARD encrypts the private key backup using the AES-256-CBC algorithm. This encrypted backup is then uploaded to our server.
• Secure Backup Password: You generate a unique Backup Password (the 12-word mnemonic) on your COLDCARD. This password is never known to us and is essential for decrypting the private key backup.
• Sharing with Beneficiaries: You share the Backup Password securely with your designated beneficiary. When the timelock expires, they can use it to decrypt the private key and access the funds.
• Inheritance Claiming Process: If the timelock has expired and all other security conditions have been satisfied, the beneficiary can initiate a transaction to claim the inheritance using the decrypted private key. The Platform Key then provides the second signature required, facilitating a smooth inheritance process.

Security Benefits

• No Access to Unencrypted Keys: The encryption of your private key is handled entirely by the COLDCARD hardware. We never have access to your unencrypted private keys, ensuring only you and your beneficiary can control your funds. Decryption occurs locally on the beneficiary’s device during the claiming process.
• Enhanced User Control: Generating your own Backup Password gives you more control over your security setup.
• Ease of Sharing: The mnemonic phrase is easier to memorize and share securely compared to a long hexadecimal string.

Comparing COLDCARD and TAPSIGNER

We recognize that each user and advisor has unique needs. Here’s a quick comparison to help you decide which device suits you best:

COLDCARD

• Backup Password: User-generated 12-word mnemonic phrase.
• Encryption Algorithm: AES-256-CBC.
• Interaction:
• COLDCARD Mk4: Supports NFC, USB, and microSD card.
• COLDCARD Q: Supports QR codes, NFC, USB, and microSD card.

Benefits:

• More control over password generation.
• Easier to memorize and share the Backup Password.
• Multiple connectivity options, including NFC and QR codes.

TAPSIGNER

• Backup Password: Factory-generated 32-character hexadecimal string.
• Encryption Algorithm: AES-128-CTR.
• Interaction: Requires a smartphone with NFC capabilities.

Benefits:

• Simplicity and ease of setup.
• Compact, credit-card-sized form factor.

Note: Using TAPSIGNER requires a smartphone with NFC capabilities.

Why This Matters

Inheritance planning is a crucial aspect of Bitcoin self-custody. By offering both COLDCARD and TAPSIGNER as options for your inheritance key, we empower you — and Bitcoin advisors through the Byzantine plan — to choose the solution that best fits your security needs and preferences.

• Flexibility: Select the device that you’re most comfortable with.
• Security: Both devices ensure that your private keys remain secure and inaccessible to unauthorized parties, including us.
• Convenience: Whether you prefer the customizable COLDCARD or the user-friendly TAPSIGNER, you can set up your inheritance plan with ease.

Conclusion

Our mission at Nunchuk is to make Bitcoin self-custody and inheritance planning accessible, secure, and user-friendly. By introducing COLDCARD as an inheritance key option, we’re providing you — and Bitcoin advisors using our Byzantine services — with more choices to secure your Bitcoin legacy.

If you have any questions or need assistance, please reach out to our support team at [email protected].

Secure your Bitcoin’s future today with Nunchuk’s Honey Badger plan.