The seed phrase is held within the Trezor T. Never, Never, Never enter your Trezor T seed phrase into Yoroi. Never ever! Otherwise you are exposing your seed phrase and compromising the security of your Trezor T.
Once you have enabled the additional passphrase feature on your Trezor T then you can think of this as an extra phrase to your normal seed phrase. Thus each passphrase entered in your Trezor T becomes a separate key generated from the one seed phrase plus the extra passphrase.
All key actions are done in your Trezor T and not in Yoroi.
Therefore it is easy to restore your wallet in Yoroi when you have deleted it. Just do the following:
- Insert your Trezor T to USB and enter your PIN to unlock it
- Open Yoroi
- Select “Add new wallet”
- Select Trezor T
- Allow the web plugin to access your Trezor T public key
- Enter your passphrase for the wallet you want to add
Basically you are just telling Yoroi the combination of your Trezor T seed phrase + passphrase. Yoroi gets the public key calculated from these two values.
Any transfers you make from this wallet on Yoroi will require you to connect your Trezor T, unlock with the PIN, and enter the passphrase.
Most importantly, understand that the passphrase referred to above in all cases is a passphrase used by the Trezor T to add to its internal seed phrase in order to generate the correct key. It is not a spending passphrase for Yoroi. Yoroi does not use this passphrase, it is used by the Trezor T.
This is in complete distinction to the passphrases used by Yoroi for other (non-hardware) wallets. For these non-hardware wallets, Yoroi uses these passphrases to encrypt the key (from seed phrase) which was generated by Yoroi.
Try using Daedalus with the same Trezor T and your Trezor T passphrases. You will be able to restore your wallets on Daedalus so you can use either Daedalus or Yoroi and see your wallets in both. Daedalus forces you to input your passphrase on the Trezor T itself using its touch screen. This will show you how this passphrase is really used by the Trezor T. Daedalus doesn’t ever see it. Importantly, you will restore your Trezor T wallets in Daedalus without entering any seed phrases.
With Yoroi, it is a bit confusing because you enter the passphrase for the Trezor T in the Yoroi web extension. However the Yoroi web extension is just providing a convenient way to enter the passphrase and is sending it directly to your Trezor T.
When you are using a hardware wallet, you generate the seed phrase on it and you write it down and store it in a safe. You never need to access this seed phrase unless your Trezor T gets lost or destroyed. Then you get another Trezor T, open your safe, and configure your new Trezor T with your seed phrase. Then you just restore your wallets as explained above. Make sure you store your passphrases somewhere safe too.