A one-time signature that can still be verified again? Yep, and @quipnetwork actually explains why in its own docs Quip Accounts use SHRINCS, a hash-based signature system designed for post-quantum protection For normal account operations, every signature consumes a slot Use it once, move to the next Pretty straightforward But things get interesting when a dApp checks signatures through ERC-1271 That verification is read-only It doesn't consume a signing slot And the same signature can continue passing verification while its key remains installed Wait, doesn't that defeat the whole one-time idea? Not exactly Signing a new message with the same one-time key and validating an existing signature again are two different operations The problem appears when a protocol assumes a valid signature automatically becomes unusable after one action Quip's documentation explicitly warns developers about this Want single-use authorization? Track nonces Add expiration Or handle key rotation Don't expect ERC-1271 to magically provide replay protection And this is what I find interesting about post-quantum wallet infrastructure Upgrading cryptography doesn't automatically upgrade every application connected to that wallet You can have stronger signatures and still introduce authorization mistakes at the integration layer Not calling this a Quip exploit It's documented behavior that developers need to account for The real challenge isn't just making wallets quantum-resistant It's making those wallets safe to integrate with the DeFi applications people already use That last part deserves way more attention