The Recovery Phrase Machine

Nothing plays until you press Play. The narration below is the same text, to read at your own pace. Each step brings its mechanism into focus in the model; the voice is not timed to the animations.

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   This guide explains how twelve ordinary words can back up a whole wallet. Everything shown here uses public test examples. Never type your own recovery phrase into any website, including this one.

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   It all begins with a long random number, like flipping a coin one hundred and twenty eight times. Real wallets take this randomness from the device.

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   The machine takes a fingerprint of that number and keeps a small piece of it. This checksum works like a spell checker for the words.

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   The bits are cut into twelve pieces, and each piece picks a word from a fixed list of two thousand and forty eight words. Words are far easier to write down correctly than bits.

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   You can add an optional passphrase. The same words with a different passphrase open a completely different wallet. If you forget it, the words alone will not bring your coins back.

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   Next, the words and passphrase are pressed together two thousand and forty-eight times. The result is the seed, the master secret from which every key grows.

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   From the seed grows a tree of keys, branch by branch. The same path always leads to the same key, which is why one backup covers them all.

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   Type the same words into another compatible wallet, with the same passphrase if you used one, and it rebuilds the same keys and addresses. That is why the words must be kept secret and safe, offline.