libgfshare2 binary package in Ubuntu Focal amd64

 This library implements Shamir's method for secret sharing, which can be
 used to split a secret (like a GPG secret key) into multiple parts, so that
 at least some number of those parts are needed to recover the original file,
 but any smaller combination of parts is useless to an attacker.
 .
 For instance, you might split a GPG key using a 3-of-5 share and put one
 share on each of three computers, and two shares on a USB memory stick; then
 you can use the GPG key on any of those three computers using the memory
 stick, but if the memory stick is lost, you can recover the key by
 bringing the three computers together.

Source package