Lost part of the mnemonic phrase

[Sauv84]

Hello. My brother lost part of a mnemonic phrase in Electrum.
He deleted a part of the phrase from the .txt file (4 words).
There was a large amount of bitcoins in the wallet.


Is there any way to restore his wallet? Thanks

[1714938549]

1714938549

[1714938549]

1714938549

[1714938549]

1714938549

[BitMaxz]

You can recover this wallet and find the missing 4 words from your backup seed phrase the only problem is I think it will take months or years depending on the PC specs.
If you have a GPU rig you can speed up the process.


There are two tools that I know that you can use to brute force the missing 4 words BTCrecovery and FinderOuter Bitcoin recovery tool.
You can find the source of BTCrecovery here https://github.com/gurnec/btcrecover
And FinderOuter here https://bitcointalk.org/index.php?topic=5214021.0

[ABCbits]

Brute force 4 missing Electrum words isn't cheap, so i have to ask whether you already think another way to restore your Bitcoin? For example,
1. Check whether your OS made backup of that .txt file. For example, Windows have feature "Enable Previous Version" which AFAIK enabled by default.
2. If you accidentally delete Electrum wallet file, you could use file recovery tool software (such as Recuva) to restore the file.

There are two tools that I know that you can use to brute force the missing 4 words BTCrecovery and FinderOuter Bitcoin recovery tool.
You can find the source of BTCrecovery here https://github.com/gurnec/btcrecover
And FinderOuter here https://bitcointalk.org/index.php?topic=5214021.0

FinderOuter is more user-friendly, but 2048^4 is rather large combination and FinderOuter lacks GPU acceleration.

[o_e_l_e_o]

Agree with both posts above.

I would use btcrecover preferentially to try to do this. Rather than use the link BitMaxz has shared (which is the link to the long abandoned original software), use this link instead (which is for a constantly updated forked version which will run faster and has better documentation on how to set up and use it): https://btcrecover.readthedocs.io/en/latest/

I would explore other means of recovering your wallet first, as 4 missing words in a known position still leaves 17.5 trillion combinations to try. This is assuming that they are in a known position. If you are missing 4 words from an unknown position, then this becomes exponentially harder and maybe impossible depending on what hardware you have available.

Do you know an address from the wallet in question (preferably the first one)? It will make the process somewhat easier if you do.

You'll also want to set up a token list with your 8 known words, but this will be pretty easy to do and I'm happy to guide you through it. Obviously don't share your other 8 words with anybody who offers to help.

[Sauv84]

The password was written on paper, he lost it and tried to recover the wallet with a mnemonic phrase
The backup on the computer is disabled.
He could try to recall the word order, but it would still be inaccurate, I guess.

[o_e_l_e_o]

He could try to recall the word order, but it would still be inaccurate, I guess.

Can you be more specific here? Are you talking about the order of the other 8 words, or the position of the four unknown ones?

Crunching the numbers, if he is missing four words AND doesn't know the order of any of the words, then you are looking at something like 2⁷³ possible combinations. This would require renting cloud computing to solve, and would be prohibitively expensive unless the wallet contained a significant amount of coins.

What exactly do you know about the order of the known words and the missing words?

[BitMaxz]

The password was written on paper, he lost it and tried to recover the wallet with a mnemonic phrase
The backup on the computer is disabled.
He could try to recall the word order, but it would still be inaccurate, I guess.

so your brother lost his password that is why he trying to restore the wallet with his seed backup the only problem is it has missing 4 words.

Can you ask your brother if his wallet with password is still there?

It might be much faster to brute-force if he remembers parts of his password than brute-forcing missing words.

[LoyceV]

But even if there's no backup, sometimes it's possible to recover file which updated/modified. I would recommend you to make raw copy of your drive (with tool such as HDD Raw Copy[1]), so later you could use recovery tools (such as PhotoRec[2] or Recuva[3]) without worry the data overwritten since you keep using it.

I'm not sure how Windows stores text files, but if it's really just stored as plain text, it would be quite easy to do a raw search for some of the known words on the entire disk.

Brute force 4 missing Electrum words isn't cheap
~
2048^4 is rather large combination

According to Ian Coleman's BIP39 Split Mnemonic, it takes 109 seconds to hack if you know 8 out of 12 words. I can't really believe those numbers, that would mean checking 161 billion combinations per second. But I am now curious how much processing power some of the professionals have for this.