What Is Multisig?

A multi-signature (multisig) wallet requires multiple private keys to authorize a transaction, rather than just one. Common configurations include:

• 2-of-3: Any 2 of 3 key holders can authorize a transaction • 3-of-5: Any 3 of 5 key holders can authorize a transaction

For estate planning, multisig provides a powerful advantage: no single person holds complete control over the funds, yet access can be maintained even if one key holder is unavailable.

Think of it as requiring two keys to open a safety deposit box — the bank has one key and you have the other. Neither can access the box alone.

Multisig for Inheritance

A well-designed multisig estate plan might look like this:

2-of-3 Configuration: • Key 1: Held by you (in your hardware wallet) • Key 2: Held by your spouse/heir (in their hardware wallet) • Key 3: Stored in your ZeroLatch vault (released via dead man's switch)

During your lifetime: You and your spouse can jointly authorize transactions (keys 1+2). You maintain control of your crypto through normal collaboration.

After incapacitation: Your spouse receives Key 3 from ZeroLatch via the dead man's switch. With keys 2+3, they can access the funds without your participation.

If both keys 1 and 2 are lost: As long as key 3 exists (in the ZeroLatch vault), it can be combined with whichever remaining key is available.

This setup provides security (no single point of failure), convenience (normal operation requires only 2 signatures), and inheritance (the dead man's switch provides the third key when needed).

Implementation

Bitcoin Multisig: Natively supported. Use tools like Sparrow Wallet, Electrum, or Caravan to set up a multisig wallet. Hardware wallets (Coldcard, Ledger) can serve as individual signers.

Ethereum Multisig: Use Gnosis Safe (now Safe{Wallet}) for smart-contract-based multisig. Supports ERC-20 tokens and DeFi interactions.

Key Distribution: Store each key separately — different hardware wallets, different physical locations, different people or services.

Testing: Before transferring significant funds, test the multisig setup with small amounts. Verify that any combination of K signatures can successfully authorize a transaction.

Multisig adds complexity but dramatically improves both security and inheritance. For significant crypto holdings, it's worth the setup effort.