We're big fans of codex32 at SeedHammer. Hand-computable, built in Shamir's secret splitting and fixes several shortcomings in BIP39 (Ctrl-F "trainwreck" in https://secretcodex32.com/faq/).

The SeedHammer machine may be the first hardware to support codex32. Below is the engraving of 2 codex32 Shamir shares that combine to a master secret.

We also wrote a command line utility and library for manipulating codex32 shares and derive BIP85 data. See https://go.dev/play/p/umS28lD8R0Q (press "Run" to see output) or use a terminal (you need Go installed):

Install the biptool command line tool: $ go install seedhammer.com/cmd/biptool@latest $ export PATH=$PATH:~/go/bin

Encode a secret with threshold 2. Usually a random key, but in our case a sentence: $ echo "Codex32 is what we do"| biptool seed -seedlen 22 -id secr -threshold 2 ms12secrsgdhkgetcxvezq6tnypmksct5ypmk2grydu9qqd7chr26ruhsn

Encode share #1: $ head -c 22 /dev/urandom | biptool seed -seedlen 22 -id secr -threshold 2 -idx a ms12secras2eph54xt3tkzjhrnp8g8k2zpaq5rrgqzu2sfvvug3l4xxqqc

Derive share #2: $ biptool interpolate -idx c

Enter the secret share and share #1, finish with Ctrl-D

ms12secrsgdhkgetcxvezq6tnypmksct5ypmk2grydu9qqd7chr26ruhsn ms12secras2eph54xt3tkzjhrnp8g8k2zpaq5rrgqzu2sfvvug3l4xxqqc ms12secrca5vwy33zw9af9w5jupyvgra6c7ang0ywqugpzm6jm8hhlv035

Now you have two Shamir shares for your secret. Combine them to extract the secret: $ biptool derive seed

Enter share #1 and #2, finish with Ctrl-D

ms12secras2eph54xt3tkzjhrnp8g8k2zpaq5rrgqzu2sfvvug3l4xxqqc ms12secrca5vwy33zw9af9w5jupyvgra6c7ang0ywqugpzm6jm8hhlv035 Codex32 is what we do

Don't have a terminal? Play along in the browser: https://go.dev/play/p/umS28lD8R0Q . Edit the program, press "Run" and see output below the code box.

#SatHunterz