An implementation of a secret sharing scheme in Rust.

wrapped_sharing contains wrapper functions that wrap around the functionality in basic_sharing, which can include using a hash placed at the end to automatically verify if the secret was properly reconstructed, ease of 'compressing' the shares by not requiring an X-value for every Y-value, and sharing/reconstructing to and from memory and files interchangeably.

This implementation uses arithmetic over GF(256), shares using wrapped_sharing use a 64-byte hash placed at the end of the of the secret before sharing that gets shared with it. This way, the reconstruction of the secret can be verified by the hash. This along with a share's corresponding X-value, puts each share at [[1-byte X value]] + [[N-byte Secret]] + [[64-byte hash (optional)]]

Notably, given N required shares to reconstruct, and M shares generated, any X number of shares where N <= X <= M can be used, without the need of specifying how many were required (using more shares however will increase reconstruction time). This goes for both wrapped_sharing and basic_sharing.

use wrapped_sharing::{Secret, share};
let shares_required = 3;
let shares_to_create = 3;
let verify = true;
let secret: Vec<u8> = vec![5, 4, 9, 1, 2, 128, 43];
let shares = share(Secret::InMemory(secret), shares_required, shares_to_create, verify).unwrap();
let mut recon = Secret::empty_in_memory();
recon.reconstruct(shares);
assert_eq!(secret, recon.unwrap_vec());

use basic_sharing::{from_secret, reconstruct_secret};
// While this just uses a single secret sharing function, there are variants for Vec<u8>
let mut rand = SmallRng::seed_from_u64(123u64); // Note that rng is optional, default seeds from entropy
let secret: u8 = 23; // The secret to be split into shares
let shares_required = 3; // The number of shares required to reconstruct the secret
let shares_to_create = 3; // The number of shares to create, can be greater than the required

let shares: Vec<(u8, u8)> = from_secret(secret,
							shares_required,
							shares_to_create,
							Some(rand)).unwrap();
let secret_recon = reconstruct_secret(shares);

assert_eq!(secret, secret_recon);