This tool allows for securely splitting and recombining secrets using a secure implementaion of the Shamir secret sharing scheme. It is a wrapper around my SSS library.

Install

You need Rust to build sss-cli from source. When you have installed Rust, you can install these tools using Cargo:

# Install sss-cli
cargo install --git https://github.com/dsprenkels/sss-cli

# Make 3 shares with recombination threshold 2
echo -n "Tyler Durden isn't real." | secret-share-split -n 3 -t 2 >shares.txt

# Take the first 2 shares and combine them
head -n 2 shares.txt | secret-share-combine

Uninstall

# Uninstall the secret sharing tools
cargo uninstall shamirsecretsharing-cli

F.A.Q.

Why are the shares so much longer than the secrets?

This Shamir secret sharing library could produce shares that are shorter than their current length. However, while Shamir secret sharing is secure for confidentiality, this is not the case for integrity. An attacker could tamper with some of the shares After restoring the (malicious) secret, you would not be able to know that it has been tampered with. sss-cli uses an AEAD wrapper so that the shares cannot be tampered with, which takes up some extra space.