SLIP-39 Mnemonics recover a unique (but "valid") Seed and derived
wallets, no matter what /alternative/ passphrase you use!  Your
/original/ Seed can only be recovered with the originally specified
"correct" passphrase.

Extendable SLIP-39 Mnemonics ensures that all SLIP-39 Mnemonic sets
generated from the /original/ Seed and original "correct" passphrase
will /always/ result in the same unique Seed for each /alternative/
passphrase.

Non-Extendable SLIP-39 Mnemonics recover the /original/ Seed with the
"correct" passphrase, but *different* unique Seeds for all /alternative/
passphrases.


1 Extendable
════════════

  The default is now /Extendable/ – does /not/ use the Identifier to
  salt the encryption passphrase.


1.1 The Purpose for Multiple Passphrases
────────────────────────────────────────

  Recovering different Seeds for different passphrases is a valuable
  feature, because you may use the same SLIP-39 Mnemonic cards, and
  supply different passphrases to recover different (but valid) Seeds
  and sets of derived HD wallets!

  • You could have a "distress" passphrase that recovers a decoy wallet
    containing a small amount of sacrificial funds, while your real
    savings are under a different passphrase.
  • One password for your personal accounts and another for business
    accounts.


1.2 Non-Extendable Encoding
───────────────────────────

  Historically, the SLIP-39 encoding used the randomly assigned
  Identifier to both 1) associate groups of Mnemonics belonging to the
  same set, but /also/ 2) to salt the Seed encryption.

  This meant that: if you created 2 sets of SLIP-39 Mnemonics for the
  same Seed – each set would lead to */same/* Seed with the "correct"
  original passphrase, but to */different/* Seeds with each "distress"
  passphrase!

  Unless all sets of SLIP-39 Mnemonics lead to the same Seeds for each
  passphrase, you are restricted to ever issue /only one/ set of SLIP-39
  Mnemonics for each Seed!  You lose the ability to recover other
  "distress" passphrase Seeds from the new sets of Mnemonics!


1.3 Issuing Multiple SLIP-39 Mnemonic Sets
──────────────────────────────────────────

  You may want to issue a simple set of SLIP-39 Mnemonics for your Seed
  to begin with, and then (later) decide to issue a more elaborate set
  of SLIP-39 Mnenmonic cards.

  Only with Extendable SLIP-39 Mnemonics, will the /alternative/
  passphrase Seeds and derived wallets be consistent.


2 Recovery
══════════

  The SLIP-39 App supports recovery from both Extendable and (historic)
  non-Extendable SLIP-39 Mnemonics.


2.1 Using <https://iancoleman.io/slip39>
────────────────────────────────────────

  Until the website is updated, you cannot (as of Dec 2024) use it to
  recover your Seed from Extendable SLIP-39 Mnemonics.
