sss-rs

A purely functional (as in, working) and likely inefficient implementation of a Secret Sharing Scheme in Rust

Not intended to be used in production code.

New Example with the current API

let dir = "./";
let stem = "test";
let num_shares = 3;
let secret: Vec<u8> = vec![5, 4, 9, 1, 2, 128, 43];
let sharer = Sharer::builder(secret)
	.shares_required(num_shares)
	.shares_to_create(num_shares)
	.coefficient_bits(32)
	.build()
	.unwrap();
sharer.share_to_files(dir, stem).unwrap();
let recon = Sharer::reconstructor(dir, stem, num_shares, PrimeLocation::Default).unwrap();
assert_eq!(secret, *recon_secret);

Old Example (makes use of raw_share functions)

let mut rand = SmallRng::seed_from_u64(123u64);
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 bit_size_co: usize = rand.gen_range(32, 65); // The number of bits for the generated coefficients
let prime_bits: usize = rand.gen_range(bit_size_co + 128, 257); // The number of bits for the prime
let mut prime: BigInt = rand.gen_prime(prime_bits).into(); // The prime number used for finite field
while prime < BigUint::from(secret) {
	// In case the prime is less than the secret, generate new ones until one is greater
	prime = rand.gen_prime(prime_bits).into();
}

let shares: Vec<Point> = create_shares_from_secret(	secret,
							&prime
							shares_required,
							shares_to_create,
							bit_size_co).unwrap();
let secret_recon = reconstruct_secret(shares, &prime, shares_required).unwrap();

assert_eq!(secret, secret_recon);

TODO:

- Currently limited to 4GB files, and memory usage issues especially when working with many shares.
	- Break up the reading in from files in chunks of N bytes to avoid high memory usage and overcome
	  the file size limitation.
- The shuffle operation was left out of the new API, mainly because it would not function after the 
  above change is implemented. May re-implement a way to shuffle the data in-file. For now this 
  will be benched.