What if someone builds a quantum computer fast enough to crack your bitcoin wallet's security and siphon off your coins?
The lock and key Think of a bitcoin wallet as a mailbox with a narrow horizontal slot at the top and a key held only by the owner.
When a user sends bitcoin, their wallet uses the private key to create a digital signature, a tamper-proof stamp.
One possible transition would be a “1-of-2” setup: the same bitcoin could be spent using either a traditional ECDSA or Schnorr key, or a post-quantum key.
Use of state Some post-quantum signature schemes need the wallet to keep track of information, called “state," after each signature.