Module keynesis::key

Keynesis Keys

This module defines some kind of keys that can be used for signing, for deriving a shared secret between 2 keys or building a hierarchical deterministic keys (see below).

Key Derivation

The key defined there can be derived. Just like with BIP32 but instead of using integer for the derivation the derivation’s path is a slice of bytes, allowing the users to build any kind of hierarchy without limiting themselves to 2^32 options.

It is then possible to define a root master key and to derive specific purpose keys from this root key.

use keynesis::key::ed25519_hd::SecretKey;

let alice_root_key = SecretKey::new(&mut thread_rng());

let alice_key_exchange_with_bob = alice_root_key.derive(b"encryption:bob");

// alice retrieves the public key from bob's root public key
// and uses it for the key exchange
let shared_secret_with_bob = alice_key_exchange_with_bob.exchange(
    &bob_root_pk.derive(b"encryption:alice").unwrap()
);

// bob can compute the shared secret with alice's root public key
let shared_secret_with_alice = bob_key_exchange_with_alice.exchange(
    &alice_root_pk.derive(b"encryption:bob").unwrap()
);

// the shared secret is the same for both alice and bob
assert_eq!(shared_secret_with_bob, shared_secret_with_alice);

SharedSecret for encryption

Once a shared secret has been established it is possible to use it to seed a stream Cipher (authenticated or not, ChaCha20 with (or without) Poly1307).

use cryptoxide::chacha20::ChaCha20;

const NONCE: &[u8] = b"0123456789ab";
let mut encryption_context = ChaCha20::new(shared_secret_with_bob.as_ref(), &NONCE);
let message: &[u8] = b"Secret Message between alice and bob";
let mut encrypted = message.to_vec();

encryption_context.process_mut(&mut encrypted);

Modules

curve25519
ed25519
ed25519_extended
ed25519_hd

Structs

SharedSecret

A Shared Secret that can be used to generate a symmetric key

Traits

Dh