SLIP-39 (Shamir Backup)

SLIP-39 is a standard for splitting a wallet backup into several shares using Shamir’s method. A set number of shares is needed to rebuild the key, and a single share reveals nothing.

Instead of one recovery phrase, you get, say, five shares, any three of which rebuild the wallet. A share is a list of 20 or 33 words from its own 1,024-word list. The standard also allows a two-level split into groups, for example “two of three groups, and in each group two of three people”. SLIP-39 was created at SatoshiLabs, the company behind Trezor, and some of its wallets support it.

It isn’t compatible with BIP-39: you can’t turn SLIP-39 shares into a 24-word BIP-39 phrase, and going the other way gives shares 59 words long. The standard also provides an optional passphrase.

The plus is resilience to losing some of the copies. The minus is more complexity and fewer programs that support it. Multisig solves a similar problem differently: it splits the key itself, not the backup.

Why it matters for your family

You can hand shares to trusted people so that none of them has access alone, but together they can rebuild the wallet. That needs clear instructions on who holds how many shares and who must be brought together. You’ll find a comparison with other methods in the guide on Shamir and SLIP-39.