Creating Ethereum, Bitcoin and other accounts is complex and fraught
with potential for loss of funds.
A BIP-39 seed recovery phrase helps, but a *single* lapse in security
dooms the account (and all derived accounts, in fact). If someone finds
your recovery phrase (or you lose it), the accounts derived from that
seed are /gone/.
The SLIP-39 standard allows you to split the seed between 1, 2, or more
groups of several mnemonic recovery phrases. This is better, but
creating such accounts is difficult; presently, only the Trezor supports
these, and they can only be created "manually". Writing down 5 or more
sets of 20 words is difficult, error-prone and time consuming.
The [python-slip39] project exists to assist in the safe creation and
documentation of [Ethereum HD Wallet] seeds and derived accounts, with
various SLIP-39 sharing parameters. It generates the new random wallet
seed, and generates the expected standard Ethereum account(s) (at
derivation path m/44'/60'/0'/0/0' by default) and Bitcoin accounts
(at derivation path m/84'/0'/0'/0/0' by default), with wallet address
and QR code (compatible with Trezor derivations). It produces the
required SLIP-39 phrases, and outputs a single PDF containing all the
required printable cards to document the seed (and the specified derived
accounts).
On an secure (ideally air-gapped) computer, new seeds can safely be
generated and the PDF saved to a USB drive for printing (or directly
printed without the file being saved to disk.). Presently, `slip39' can
output example ETH, BTC, LTC and DOGE addresses derived from the seed,
to illustrate what accounts are associated with the backed-up seed.
Recovery of the seed to a Trezor is simple, by entering the mnemonics
right on the device.
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The SLIP39.app is signed by Perry Kundert, but the signature is not yet recognized
as a known App Developer. Therefore, you will have to approve the app in System Preferences /
Security & Privacy / Privacy.