BIP85 deterministically derives child seeds from a parent seed. The same parent seed and index always produce the same child, so you can back up one seed phrase and derive as many child wallets as you like from it.
SeedSigner's BIP85 support lets you generate a child seed, load it, and use it like any other in-memory seed. (BIP85 is also used for GPG keys, which have their own documentation.)
- Load the parent seed.
- On the seed's Seed Options screen choose BIP-85 child seed.
- Choose the child's word count: 12, 18 or 24 words.
- Choose the index (0, 1, 2, …). Different indexes give different children.
- SeedSigner derives the child and shows it. You can verify/transcribe it like any seed, or finalize it into memory to use for signing.
BIP-85 child seeds must be enabled in Settings → Advanced (enabled by default).
A finalized child seed behaves like a normal seed:
- Seed Options → Export xpub / Address explorer / Sign message
- Backup seed (words, SeedQR, or to a SeedKeeper)
- Scan a PSBT to sign with it.
Because derivation is deterministic, you do not need to back up each child seed — backing up the parent seed and recording the index is enough. That is the point of BIP85, and also its risk: anyone with the parent seed can derive every child.
The Password Generator can use BIP85 as its entropy source to derive a password deterministically from a loaded seed, for password types it supports.
SeedSigner's BIP85-derived GPG keys have changed derivation scheme across releases; see BIP85 GPG version history. Plain BIP85 child seeds use the standard BIP85 path.