Please how can a seed phrase extension used to create a passphrase?
The passphrase is not used to create the seed phrase. The passphrase is an optional security layer that you can add on top of the seed phrase to increase the overall security of your wallet.
To simplify what hosseinimr93 was talking about.
If you have a wallet protected with a 12/24-words seed phrase, and someone finds your seed, that person can spend all the coins from that wallet.
If you have a wallet with a 12/24-words seed phrase, plus an additional passphrase, the hacker would need both to spend your funds. The seed alone wont give him access to the coins protected with the passphrase.
You will see the difference if you play around with that feature on Electrum. Create a new wallet on Electrum just for testing the passphrase feature.
- Create one standard wallet without a passphrase.
- Save the seed somewhere.
- Open the wallet and save one of its addresses.
- Now restore your wallet from the same seed and you will find the same address that you saved previously.
- Create a second wallet, restore it from the same seed as above.
- During the restoration process, extend the seed with a passphrase.
- Follow what hosseinimr93 suggests in his last sentence on how to do that.
- Open the wallet and check its addresses.
- You will notice that it has a completely different set of addresses compared to the first one without the passphrase.
- Try to find the saved address from wallet 1. You will notice it's not there.
For the purposes of this test, it's ok to save the seed digitally. It's faster to copy/paste it to restore the wallet. But you should never do it with a real seed that holds your coins.