BIP39 Passphrase

Generate a strong passphrase with dice and the EFF wordlist.

What it is

A BIP39 passphrase is an optional "25th word" added to your seed phrase. It is not stored on the blockchain and is not part of the 12/24 words — it is a single secret string you choose and must remember. The same seed plus a different passphrase produces a completely different wallet, so a passphrase acts as a second factor: even if someone finds your seed phrase, they cannot access your funds without the passphrase.

Critical Warning

If you lose the passphrase, the wallet is unrecoverable — no one can restore it, ever. There is no "forgot passphrase" flow. Store it carefully and separately from your seed phrase.

The EFF Dice Method

The Electronic Frontier Foundation publishes a free wordlist designed specifically for generating strong passphrases with physical dice. Each word is chosen by rolling five dice and looking up the result — giving you a passphrase you can recreate from dice and the published list, with no computer required.

Steps

  1. 1

    Roll five dice at once (or one die five times) and record the five digits in order, e.g. 42156 .

  2. 2

    Look up that 5-digit number in the EFF large wordlist to find the matching word, e.g. 42156 → stumper .

  3. 3

    Repeat for as many words as you want — 5 to 7 words makes a very strong passphrase.

  4. 4

    Write the words down in order, separated by spaces or hyphens. That string is your passphrase.

Example

Five rolls of five dice each:

42156   33124   55201   21344   46432

Looked up in the wordlist becomes, for example:stumper-glimpse-outgas-rebating-yummy

Important Notes

  • The EFF large wordlist contains 7,776 words (6^5) — each roll maps to exactly one word.
  • A 5-word passphrase from this list provides roughly 51 bits of entropy; 6 words ≈ 62 bits; 7 words ≈ 72 bits.
  • Generate the rolls on a clean, offline surface. Never reuse the same roll sequence twice.
  • Store the passphrase separately from your seed phrase — together they control your wallet.

Using the passphrase

When you import your seed into Sparrow, a hardware wallet, or any BIP39-compatible tool, look for the "passphrase" or "BIP39 passphrase" option and enter your dice-generated words there. The same seed + the same passphrase always opens the same wallet — get one character wrong and you get a different, empty wallet (which is why you should test with a small amount first).