Question about passphrase after wallet creation

[xfuhmc]

Hi everyone,

I created an Electrum wallet with 12 seed words. At that time, I didn’t enable the “custom words / passphrase” option.

Now I’m wondering: can I import this wallet with the same 12 seed words, and then add my own custom word (passphrase) to generate an extended wallet?

What is the difference between (1) enabling the passphrase option when creating the wallet from the beginning, and (2) creating a standard wallet first and only adding the passphrase later when importing the seed?

Thank you for your help!

[rat03gopoh]

It's not the same.
(1) Electrum will automatically generate keys from the seed+passphrase. This means the private key, address, and balance will be completely different from those generated without the passphrase from the beginning.
(2) It's like generating a new wallet, while the "standar" wallet from the same seed without the passphrase can still be accessed with a different profile.

[nc50lc]

What is the difference between (1) enabling the passphrase option when creating the wallet from the beginning, and (2) creating a standard wallet first and only adding the passphrase later when importing the seed?

Nothing much in its keystore derivation process, it just the result that will obviously be different since the data you input are different.

Under the hood, Electrum does the same to the seed phrase and passphrase or seed phrase w/o a passphrase:
When creating the binary seed, it takes the seed phrase (mnemonic) and "electrum+<passphrase>" as salt; in case there's no passphrase, the salt is just "electrum"
And pass those to 2048 rounds of PBKDF2 HMAC-SHA512 algorithm.

Here's how it looks in the code: spesmilo/electrum/mnemonic.py#L170-L175

[satscraper]

What is the difference between (1) enabling the passphrase option when creating the wallet from the beginning, and (2) creating a standard wallet first and only adding the passphrase later when importing the seed?

Nothing much in its keystore derivation process, it just the result that will obviously be different since the data you input are different.

Under the hood, Electrum does the same to the seed phrase and passphrase or seed phrase w/o a passphrase:
When creating the binary seed, it takes the seed phrase (mnemonic) and "electrum+<passphrase>" as salt; in case there's no passphrase, the salt is just "electrum"
And pass those to 2048 rounds of PBKDF2 HMAC-SHA512 algorithm.

Here's how it looks in the code: spesmilo/electrum/mnemonic.py#L170-L175

Just to stretch this a bit for OP.

PBKDF2 algorithm requires two inputs.One of those is  'mnemonic' while the other is 'salt'. In the case of OP when he prefered not to set the passphrase, 'salt'equals to string "mnemonic". However, if OP provided the passphrase, let's say "bla_bla_bla", the salt becomes the concatenation of "mnemonic" and the passphrase, resulting in "mnemonicbla_bla_bla". Essentially, the passphrase is appended to the "mnemonic" string to form the salt.

[nc50lc]

Just to stretch this a bit for OP.

A little correction though, 'mnemonic' is for BIP39.
Electrum implements it like this: spesmilo/electrum/keystore.py#L1003-L1010

In Electrum, the salt is 'electrum' + seed phrase extension (passphrase) like I mentioned in my reply.
Refer to the link I've provided for reference.

[Abdussamad]

Hi everyone,

I created an Electrum wallet with 12 seed words. At that time, I didn’t enable the “custom words / passphrase” option.

Now I’m wondering: can I import this wallet with the same 12 seed words, and then add my own custom word (passphrase) to generate an extended wallet?

Yes.

What is the difference between (1) enabling the passphrase option when creating the wallet from the beginning, and (2) creating a standard wallet first and only adding the passphrase later when importing the seed?

Thank you for your help!

It'll generate a completely new wallet with different addresses than the passphrase-less one.

[satscraper]

Just to stretch this a bit for OP.

A little correction though, 'mnemonic' is for BIP39.
Electrum implements it like this: spesmilo/electrum/keystore.py#L1003-L1010

In Electrum, the salt is 'electrum' + seed phrase extension (passphrase) like I mentioned in my reply.
Refer to the link I've provided for reference.

Nice correction, but we can't be sure which SEED scheme OP uses, whether it's native Electrum or BIP39 ^{default is Electrum but thiswallet supports both}. I mentioned BIP39 because it’s my preferred scheme, as it's widely used by nearly all other major wallets. On the other hand, Electrum's native approach is unique and requires you to use that specific wallet if anything unexpected happens.

[xfuhmc]

Thank you everyone for the detailed explanations!
It helps a lot.

[Pmalek]

A wallet without an additional passphrase is completely different from one with a passphrase. You can't turn one into the other. If you have a funded wallet with no passphrase and you tried to recover it, you will have to leave the passphrase field empty to see the bitcoin in your software. Anything you add as passphrase would create a brand-new and empty wallet and not the one you funded in the past.

You can still extend an existing wallet with one or multiple custom passphrases that you can fund and use in the future. But when it becomes time to recover those new wallets, you will also have to input the correct passphrase exactly as you typed it in during the creation process. 

[OcTradism]

It's not the same.
(1) Electrum will automatically generate keys from the seed+passphrase. This means the private key, address, and balance will be completely different from those generated without the passphrase from the beginning.
(2) It's like generating a new wallet, while the "standar" wallet from the same seed without the passphrase can still be accessed with a different profile.

To help OP more easily learn about difference between a wallet with mnemonic seed and another wallet with same mnemonic seed and a passphrase.
https://learnmeabitcoin.com/beginners/security/#passphrase

The passphrase is important as same as the wallet mnemonic seed as without one of them, you can not recover a wallet as your original wallet. Wallet passphrase is like a second layer of your wallet security and protection so making sure storing it in a different place than where you store your wallet mnemonic seed. Trying to remember that wallet passphrase too.