● Proposal for using one BIP32 keychain to seed multiple child keychains: several weeks ago, Ethan Kosakovsky posted to the Bitcoin-Dev mailing list a proposal for using one BIP32 Hierarchical Deterministic (HD) keychain to create seeds for child HD keychains that can be used in different contexts. This may seem unnecessary given that BIP32 already provides extended private keys (xprvs) that can be shared between signing wallets. The problem is that many wallets don’t implement the ability to import xprvs—they only allow importing either an HD seed or some precursor data that is transformed into the seed (e.g. BIP39 or SLIP39 seed words).

Kosakovsky’s proposal is to create a super-keychain whose child keys are transformed into seeds, seed words, or other data that can be input into various wallets’ HD keychain recovery fields. That way a user with multiple wallets can backup all of them using just the super-keychain’s seed (plus the derivation paths and the library for transforming deterministic entropy into input data).

Reaction to the proposal was mixed (pro: 1, 2; con: 1, 2), but this week one hardware wallet manufacturer stated their intent to implement support for the protocol and requested additional review of the proposal.