python-shamir-mnemonic VS seedtool-cli

You can recover with regular Linux/MacOS/Windows computer using this python script https://github.com/trezor/python-shamir-mnemonic

I suggest you do some further reading here https://github.com/trezor/python-shamir-mnemonic/issues/15

You can use Electrum or any third party wallet to enter the seed phrase. Otherwise with Shamir use https://github.com/trezor/python-shamir-mnemonic/

For even more security, shard the mnemonics with Shamir's secret sharing.

I do hope multisig gets easier in the comming years, but just the same, Shamir could also be standardized (the trezor team has already done the work and has the proposal and implementation) in the same way.

I mention that in the issue. The problem is this rationale seems unjustified because a 12-word BIP-0039 mneumonic encodes 16 bytes (128 bits) + 4 checksum bits of information before the passphrase comes in https://github.com/trezor/python-shamir-mnemonic/issues/40

However, the trezor reference implementation only allows to be given an existing secret in the form of hexadecimal seed key and not the actual mnemonic, as provided.

Trezor support Shamir backups (at least the model T does), but the cold wallet itself should be stored in the safety deposit box with the bank too (because if you know the device password and have the wallet with you then you are vulnerable to a wrench attack). You can generate one for an existing seed phrase with this command line tool also: https://github.com/trezor/python-shamir-mnemonic/

This gives me a hexadecimal seed. I'm using Blockchain Common's seedtool-cli to convert the hex to bip39.

The short encoding of the SSKR shares is called byteword minimal. You can play with this tool to convert from one format to the other: https://github.com/BlockchainCommons/seedtool-cli

If a Shamir's Secret Sharing solution is not implemented on Ledger anytime soon then seedtool-cli is available friom Blockchain Commons which can convert your BIP-39 recovery phrase to SSKR (BCR-0011) and vice versa e.g, the following command generates SSKR shares: with k-of-n threshold 2-of-3:

Have you tried https://github.com/BlockchainCommons/seedtool-cli

If you are familiar with linux you can go the extra mile and use a proper cryptographic tool for splitting your seed, based on Shamir's Secret Sharing Scheme to encrypt your seed to multiple parts (eg. a 3-of-5 scheme where any 3 keys decrypt the seed). You can find it here. It outputs a list of hex strings, or, alternatively, a set of mnemonic word lists that individually have no relation to your true seed but can be combined to recreate your seed.

Here is a tool that let's you do it. Recommend a linux distribution on an offline computer (dig up that old laptop that takes 30 mins to boot windows and install a lightweight linux distribution).