Passphrase (the ‘25th word’)

The passphrase is an optional extension of the BIP 39GlossaryBIP 39 (standard for seed words)The widely used standard that turns random data into 12 to 24 words from a fixed list of 2,048 words. Your wallet calculates all its keys from these words – BIP 39 is behind most seed phrases.On the learning path: Stage 5 · Step 3 – Backing up your seed phrase →In the glossary →× standard: a word or sentence of your choice that is added to your seed phraseGlossarySeed phrase (recovery phrase)A sequence of usually 12 or 24 words from which your wallet derives all its private keys. Anyone who knows the words has full access to your bitcoin – so they belong in an offline backup and never in anyone else’s hands.On the learning path: Stage 5 · Step 3 – Backing up your seed phrase →In the glossary →× – with 24 words, hence the ‘25th word’. Unlike a PIN, which only locks the device, it changes the wallet itself.

How it works

Every passphrase produces a valid but different wallet.^[1] There is no error message: if you make a typo, a different, usually empty wallet opens. Every character counts, including upper and lower case.^[2]

This protects you if someone finds your seed phrase: they only see the wallet without the passphrase. A small amount in it can serve as a decoy under duress, see wrench attackGlossaryWrench attack ($5 wrench attack)An attack using violence or threats instead of technology: criminals force Bitcoin owners to unlock their wallet or transfer bitcoin. The best protection is discretion – if nobody knows you own bitcoin, you are less likely to become a target.On the learning path: Stage 6 · Step 2 – Spotting scams →In the glossary →×.

The downside

Nobody can recover a forgotten passphrase, not even the maker of your device – the funds are then lost.^[2] So write it down, keep it separate from your seed phrase, test the recovery and leave your heirs a pointer to it.

When you’re starting out, you usually don’t need a passphrase – every extra layer is also a source of mistakes. In detail: The passphrase (the ‘25th word’).