bruteforce 12 words seed

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?

seed

entarex11

Posted 2018-10-31T11:36:40.347

Reputation: 1

Answers

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 definately brute forcable.

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

Mike D

Posted 2018-10-31T11:36:40.347

Reputation: 1 571

thank for answer. Im whant to use Electrum. What are my options for enhancing seed phrase backup? @Mike-D – entarex11 – 2018-10-31T12:32:59.233

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 – 2018-10-31T12:43:46.057

What should I to import to electrum ? I generated 24 seed from https://iancoleman.io/bip39/ , but electrum don't whant to import it.

– entarex11 – 2018-10-31T12:51:54.527

make sure you tick BIP39 in the options dialog – Mike D – 2018-10-31T13:44:03.667

"every passphrase generates a valid seed" https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki#from-mnemonic-to-seed

– JBaczuk – 2018-10-31T18:44:26.700

@JBaczuk that refers to adding an extra word (eg 13th or 25th word) to the mnemonic as a ‘passphrase’. Any such passphrase will generate a valid wallet. The mnemonic itself includes a checksum, so not all permutations of a certain mnemonics’s words will be valid seeds (as the checksum will be invalid). – chytrik – 2018-10-31T19:38:59.860

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.

MCCCS

Posted 2018-10-31T11:36:40.347

Reputation: 5 827

thank for answer. Im whant to use Electrum. What are my options for enhancing seed phrase backup? @MCCCS – entarex11 – 2018-10-31T12:41:00.970