Private key

A private key is a secret number the owner uses to sign crypto transactions. Whoever has it can spend the funds tied to the linked addresses; whoever doesn’t can’t move a single coin.

A public key is calculated from the private key, and a wallet address from that. It doesn’t work in reverse: nobody can rebuild the key from an address. That’s why you can give an address to a sender, but you give your key to nobody.

Day to day, you don’t see the private key. The wallet holds it inside and signs transactions with it, and a hardware wallet does that in a device the key never leaves. Modern wallets generate many keys at once from one recovery phrase, so that phrase is the backup of the whole set.

A signature doesn’t reveal the key, and a sent transaction is irreversible. There’s no helpline that can undo it.

Why it matters for your family

Inheritance law passes assets to heirs, but it doesn’t hand them the key. Without the key, a notarial deed or a court ruling achieves nothing, because the bitcoin network recognises only a signature. That’s why instructions for your family must say where the copy of the phrase is and how to use it. We describe what they should contain in the guide on access instructions for your family.