BIP 322 — Generic Signed Message Format

BIP 322 (Generic Signed Message Format) defines a standard way to sign and verify messages for any script type — including SegWit and Taproot outputs — generalizing the legacy sign-message feature that only worked for P2PKH addresses. Repository status: Complete (specification finished); wallet adoption remains partial.

Debate relevance: Appears in proof-of-reserves and 'prove you control this address' discussions, which recur whenever custodian solvency is debated. Common misstatements: "You can sign a message from any address type with the old signmessage" — legacy signing covers only P2PKH; BIP 322 exists precisely to fill that gap. A signature proves control of keys at signing time, not continued ownership of funds.