Monero seeds

Biscuit creates 16-word Monero seeds, called Polyseeds, and restores the older kinds too.

Polyseed, 16 words

Polyseed is the format Biscuit and Feather use. Compared to Monero’s classic 25-word seed:

it contains the wallet’s creation date, so you never need a restore height;
it uses the BIP39 word list, with short and common words;
it’s quicker to write down.

Wallets that don’t know Polyseed can still open your wallet: Wallet › Seed › Show 25 word seed gives the same wallet as a 25-word seed. Note the restore height shown with it. The other way round isn’t possible: a 25-word seed can’t become a Polyseed, because Polyseed derives the key in a way that can’t be reversed.

Older seeds

25 words: Monero’s classic seed, from the official wallets, Cake Wallet and many others. Biscuit restores it; pick its language.
14 words: Feather’s seeds before version 2.0. Biscuit restores them too, with no need to move your coins.

12 or 24 words are not a Monero seed: they’re a Bitcoin seed (BIP39 or Electrum). Biscuit uses 12 words for its Bitcoin and Litecoin wallets.

Seed passphrase

A Polyseed can be extended with a passphrase (Options, when creating or restoring). The seed alone then opens a different, empty wallet: you need both. It protects you if someone finds the paper, but if you forget the passphrase, the coins are gone. This is not your wallet password. If unsure, don’t use one.

Extra randomness from dice

Your computer’s random number generator makes the seed. If you’d rather not rely on it alone, in a virtual machine or a live system for example, you can mix in dice rolls or coin flips. On the seed page of Create new wallet, press Ctrl+K.

Dice: choose the number of sides. A D6 needs 59 rolls, a D12 42, a D20 36. The die must show 1 to N, with no 0 and no skipped numbers. Several dice at once is fine if they’re the same kind: read them left to right, don’t sort them, don’t reroll.
Coins: click Heads or Tails for each flip.

Biscuit mixes your rolls with the system’s randomness, then fills in the new seed. Don’t write the rolls down: they can’t recreate the seed. Write the seed.

Recovering a damaged seed

A word smudged, cut off, or missing, but you know where it goes? The recovery tool can try the possibilities. It works for 16-word Polyseeds only, and only if the words are in the right order.

First, compare what you can read with the BIP39 word list. Often that’s enough.
Otherwise, choose Restore wallet from… › Seed and press Ctrl+K.
Enter each word you know in its box, and leave unknown ones empty. Partial words work as patterns: his for a word starting with his, ory$ for one ending in ory, ^hi.*y$ for both, history|victory for either.
Click Check. Each missing word makes the search much longer. If it takes too long, click Cancel: with too many unknown words, recovery isn’t possible.