Compact Encryption Scheme for Non-seed Wallet Data.

Would encrypt a wallet's setup details so backups can be stored anywhere, and opened only by the wallet's own keyholders.

Wallets that need several keys also need a record of which keys and rules they use, and losing it can be almost as bad as losing the seed. This lets you keep an encrypted copy online without exposing addresses or keys. Listed cosigners open it with their xpub. Private keys must never go in it.