How to get master phrase for shamir

I just got a Trezor T - i’m using Shamir backup

I want to know the master seed phrase as well as the shamir shares.

How do i accomplish this?

There isn’t any master phrase. The shares themselves are your backup.

In particular, there is no way to convert a Shamir backup into a BIP-39 12- or 24- word single backup that you could import into a different wallet. You can only import into Shamir-compatible wallets.

If what you want is to have both (a) a 3-of-5 (or another) set of shares that you distribute to your friends, and (b) a single phrase that you yourself can use to recover the Trezor, that can be done by using SuperShamir:

  1. set your Group Threshold to 1 (one group is sufficient to recover)
  2. configure your first group as you like, e.g., 3 out of 5
  3. configure a second group to be 1 out of 1.

This will give you 6 shares in total: 5 of them have the same 3 first words, the 6th has the same 2 first words but a different third one. This sixth share alone is enough to recover your wallet. If you lose it, you will need to complete a quorum of 3 out of the 5 remaining shares.

Thank you so much for this.

  1. How do i go about implementing this on the device i already have setup with regular shamir.

  2. Is the second group also a 20 word phrase? In an ideal world i would like to have a 12 world phrase i remember and then a group with a separate set of shares which i can give to friends.

Unfortunately, Trezor does not currently support a way to regenerate shares of an existing secret.
You would need to set up a completely new SuperShamir backup with the configuration that you want, and move your funds to the newly generated addresses.

(This can be done with a single Trezor, although the process is quite long:

  1. wipe your device
  2. set up a new SuperShamir backup with the configuration that you want
  3. write down receiving addresses for your funds
  4. recover your previous backup
  5. send funds to the new receiving addresses
  6. recover the newly generated backup to regain access to the moved funds.

Yes, the second group is also 20 words.

But yours is the first good idea I heard that involves memorizing a mnemonic :slight_smile: That’s something to be discouraged in the typical case, because the human memory is not reliable enough for this purpose. But if you have a “backup of a backup” in the form of the other set of shares, that would work quite well.