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Backups

9 min read

Recovery words are the only thing standing between you and total loss. How BIP39 words, an optional passphrase and durable, offline storage fit together.

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Answer every question correctly (100%) to complete this lesson.

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BIP39 turns a source of randomness into a word list drawn from a fixed 2048-word dictionary, plus a built-in checksum. That checksum is why one wrong or reordered word usually makes the whole phrase invalid rather than silently pointing at someone else's wallet.

An optional passphrase (sometimes called a 25th word) is combined with the words during seed derivation. It is not stored anywhere and not recoverable from the words alone: forgetting it is equivalent to losing the backup entirely, with no reset available.

A backup is only proven once restored: load the words into a fresh wallet instance (or the same wallet after a factory reset) and confirm the first receive address matches before depositing meaningful amounts. An unverified backup is a guess.

Explain more simply

When a wallet is set up, it shows a list of 12 or 24 words, in order. Those words can recreate every key the wallet will ever use.

Write them down on paper or stamp them into metal, keep them offline, and store the copy somewhere only you (or people you trust for inheritance) can find.

Never store recovery words as a digital photo, in cloud storage, in an email, or typed into any website, a photo can be synced, backed up, hacked or leaked without you realising it.

Real-world analogy

Recovery words are less like a password and more like the master blueprint of a vault: whoever holds the blueprint can build a working copy of the vault door anywhere.

Key facts

  • 12 or 24 words, in exact order, can recreate every key a wallet will ever derive.
  • The BIP39 checksum catches most single-word mistakes but not a fully wrong phrase.
  • A passphrase creates a separate wallet with no recovery if forgotten.
  • Only a tested restore proves a backup actually works.

Common misconception

“A photo of my recovery words in a locked phone is a safe backup.”

Photos routinely sync to cloud accounts, get indexed by AI photo-search, appear in backups of the phone itself, or survive in a photo library after a phone is sold. A digital copy multiplies the number of places a secret can leak from.[7]

Go deeper

Technically, BIP39 stretches the mnemonic with PBKDF2-HMAC-SHA512 (2048 rounds), using the literal string "mnemonic" plus the optional passphrase as salt, to produce the 512-bit seed that BIP32 then turns into a master key.

Because any passphrase produces a mathematically valid wallet, there is no way to detect a mistyped passphrase, it just derives a different, empty-looking wallet, which is both a deniability feature and a common source of apparent loss.

Redundancy without central risk usually beats a single, perfect copy: geographically separated metal backups, or a multisig setup with keys split across locations, tolerate the loss of any one copy or location.

Quick check

Answer every question correctly (100%) to complete this lesson.

  1. 1.What is the safest way to store recovery words?

    What is the safest way to store recovery words?

  2. 2.What happens if you forget an optional BIP39 passphrase?

    What happens if you forget an optional BIP39 passphrase?

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Extra exam questions

Every question here counts towards your accuracy, XP and rank. No guessing: every answer is explained.

16 questions

Quick check

Answer every question correctly (100%) to complete this lesson.

  1. 1.What is the primary purpose of a wallet backup?

    What is the primary purpose of a wallet backup?

  2. 2.Why should a backup have more than one physical copy in separate locations?

    Why should a backup have more than one physical copy in separate locations?

  3. 3.What is the recommended way to confirm a backup actually works?

    What is the recommended way to confirm a backup actually works?

  4. 4.Why is metal often recommended over paper for long-term seed phrase backups?

    Why is metal often recommended over paper for long-term seed phrase backups?

  5. 5.What is a mistake many people make when backing up a wallet digitally?

    What is a mistake many people make when backing up a wallet digitally?

  6. 6.How often is it recommended to review and re-test your backup?

    How often is it recommended to review and re-test your backup?

  7. 7.What should you do with an old backup after generating a brand-new seed phrase for a different wallet?

    What should you do with an old backup after generating a brand-new seed phrase for a different wallet?

  8. 8.Why is it dangerous to write your seed phrase on a note stored inside your house near the hardware wallet itself?

    Why is it dangerous to write your seed phrase on a note stored inside your house near the hardware wallet itself?

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