keyfunc mnemonic prints a child mnemonic derived from the main one with
BIP-85's own mnemonic application, in English, at 12, 18 or 24 words.
Its entropy is the BIP-85 entropy cut to the length the word count
needs, which is what that application asks for, so it does not go
through the generator the other key types read their bytes from. The
BIP-85 specification's own test vectors for the application are the
tests.
Two pieces the derivation package already had inside one function are
now named: the master key a mnemonic stands for, and the refusal of a
key index that has no hardened child. Both key types call them.
Model: opus-5
The module, the script entrypoints and Makefile, Docker-only linting, the mnemonic sources in the specified order with their refusals, the BIP-85 derivation, and keyfunc ssh pub and priv with the README test vectors as tests. Two review rounds; the second passed with no findings.
Model: opus-5 (implementation and review); fable-5-1 (landing)
The README is the specification sneak approved on 2026-09-07, moved
here from the hacks repository: deterministic SSH keys, age identities
with encrypt and decrypt, and child mnemonics, all derived from one
BIP-39 mnemonic and stored nowhere.
Model: fable-5-1
