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Suppose that someone seized my seed with a phrase of 12 words. I deliberately changed the order of words in a phrase in such a way that the only way to get a real phrase is to go through all the possible combinacies of the current 12 words.

1) How many combinations will it be necessary to go through an attacker in order to find a real seed? How long can it take?

2) Do you find such precaution really effective?

2 Answers 2

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  1. The answer is 12! = 479,001,600 possible mnemonics (less if there are repeated words). Out of these only ~29,937,600 (1 in 16) produce a valid seed. This is definitely brute forceable.

  2. No, if you want to do this use a longer mnemonic (and make sure you permute them in a truly random way).

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  • thank for answer. Im whant to use Electrum. What are my options for enhancing seed phrase backup? @Mike-D
    – entarex11
    Commented Oct 31, 2018 at 12:32
  • create a new wallet with 24 words mnemonic (not with electrum, they don't support bip39) and then import it to electrum and move your funds there.
    – Mike D
    Commented Oct 31, 2018 at 12:43
  • What should I to import to electrum ? I generated 24 seed from iancoleman.io/bip39 , but electrum don't whant to import it.
    – entarex11
    Commented Oct 31, 2018 at 12:51
  • make sure you tick BIP39 in the options dialog
    – Mike D
    Commented Oct 31, 2018 at 13:44
  • "every passphrase generates a valid seed" github.com/bitcoin/bips/blob/master/…
    – JBaczuk
    Commented Oct 31, 2018 at 18:44
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Permutation(12,12) = 12! = 479,001,600

Vanitygen on GTX 1080 can derive 50 million addresses in one second. 479/50 = ~9.5 thus it'll take 9.5 seconds to derive all addresses and find your private key. As this was a master password instead of a private key, it will take a little longer. Let's say at most 2 minutes.

Not effective at all, except that it might take up to week day for the thief to think of rearranging the words.

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  • thank for answer. Im whant to use Electrum. What are my options for enhancing seed phrase backup? @MCCCS
    – entarex11
    Commented Oct 31, 2018 at 12:41

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