Electrum seed generation options

[dwitten]

Hi, I have a few seed/security questions:


1) Am I correct in assuming that I can effectively create a "brain wallet" with Electrum by creating a sha256 hash of whatever secret phrase or set of words that I want to use, and then making an Electrum wallet using that hash as a seed, rather than having the wallet create a wordlist for me?

2) If, in using the sha256 hash as my seed, I select the BIP39 option to create a wallet with segwit addresses, I can ignore the warnings about future BIP39 compatibility as long as I have/use the original sha256 hash that I created the wallet with as a seed?

3) I noticed in experimentation that I can even use a sha512 hash as a seed when I select the BIP39 option. Seems like using a sha512 hash for this would be "wasted entropy", as it would provide more entropy than the seed conversion algorithm could translate into a private key.
Correct?

Thanks to any & all who weigh in on these questions. I'm trying to learn more about encryption & the calcs that go into key and wallet creation, and Electrum is interesting in how it does things a bit differently.

[1714114367]

1714114367

[1714114367]

1714114367

[1714114367]

1714114367

[1714114367]

1714114367

[Abdussamad]

1. This is a recipe for getting robbed. Humans are not a good source of randomness so whatever phrase you come up with will not be secure. See here.

2. bip39 doesn't result in segwit wallets. maybe you mean selecting the p2sh segwit derivation path? the warning for bip39 compatibility will apply to you too regardless.

3. when you check bip39 it lets you type anything in the seed box. as mentioned in 1 your seed has poor entropy because you are generating it yourself. hashing it with sha256sum or sha512sum doesn't make any difference.

[dwitten]

Thank you very much for your advice. I have read many warnings about the false security of brainwallets, and your link is one of the strongest & best ones.

To clarify, I havent decided to implement the wallet I mentioned...for now it's more of a learning exercise that I was considering.

1) The seed would be about a half-dozen "made up" words from a short story for children that I wrote many years ago, and never shared with anyone.. The "made up" words
aren't real words in any language and as such, are in no dictionary and I've never heard them anywhere else.

My thought was to take those "fake" words that I remember well, and hash them as a string, then using a script, run the result through several thousand more hashes
to generate a seed. It does seem like a lot of trouble compared to just writing down seed words, but this is a learning exercise for me, so it's largely theoretical.

2) Also, I didnt state the BIP39 question well, and I appreciate your clarification. My desire would be a segwit wallet, but my real concern is whether I could use the sha256 hash, or the resulting xpriv
generated from the method described above to restore the wallet in Electrum in the future.

3) Question # 3 was more academic than anything. Assuming I used a cryptographically secure method to generate a random 256 bit and 512 bit seed hash, would I get any extra entropy
benefit in electrum from using the random 512 bit instead of the random 256 bit seed?

Lastly, I see that you are connected with the bitcoinpakistan site. I have come across your site before and I think it is an excellent resource. Thank you for your work and help to us all.

[Abdussamad]

no it doesn't make any difference if you hash with sha512sum or sha256sum. in fact you need not hash it at all. just enter whatever random bits you have into the seed entry field. like i said before electrum will let you put anything in there if you check the bip39 option. you can even click on the little folder icon in the corner to load the entropy/seed from a file.

as for backups you can always rely on soft copy backup of the electrum wallet via file menu > save copy. a wallet file backup will include the derived xpriv so everything you need is in there.

if you want to create a p2sh segwit wallet i have a guide here for it.

[Rayser]

You can download the https://iancoleman.io/bip39/ and create a BIP39 seed offline.

[tarball]

2. bip39 doesn't result in segwit wallets. maybe you mean selecting the p2sh segwit derivation path? the warning for bip39 compatibility will apply to you too regardless.

Actually, it can. When you import a BIP39 seed into Electrum, you can choose derivation of 44 (p2pkh), 49 (p2sh(p2wpkh)), or 84 (p2wpkh). You will get native segwit by choosing 84 derivation.