Rust implementation of the key derivation tree used in TimeCrypt(Link).

cargo build

Initialize the Key Derivation Tree with the master secret key and 32 bit inputs.

let key = [0u8; 16];
let prf = ConstrainedPrf::init(32, key);

Derive the i-th key.

let key_out = prf.apply(i).unwrap();

Give access to the keys in the range [1,15).

let node_keys = prf.constrain(1, 15).unwrap();

Initialize the Key Derivation Tree with the constrained nodes.

let prf2 = ConstrainedPrf::new(32, node_keys);
// derive key ok
let key_out = prf.apply(2).unwrap();
// derive key error
let key_out = prf.apply(0).unwrap();

cargo bench

This is a research prototype.