Module k256::ecdh

This is supported on feature="ecdh" only.

Elliptic Curve Diffie-Hellman (Ephemeral) Support.

This module contains a high-level interface for performing ephemeral Diffie-Hellman key exchanges using the secp256k1 elliptic curve.

Usage

This usage example is from the perspective of two participants in the exchange, nicknamed "Alice" and "Bob".

use k256::{PublicKey, ecdh::EphemeralSecret};
use rand_core::OsRng; // requires 'getrandom' feature

// Alice
let alice_secret = EphemeralSecret::generate(&mut OsRng);
let alice_public = PublicKey::from(&alice_secret);

// Bob
let bob_secret = EphemeralSecret::generate(&mut OsRng);
let bob_public = PublicKey::from(&bob_secret);

// Alice computes shared secret from Bob's public key
let alice_shared = alice_secret.diffie_hellman(&bob_public)
    .expect("bob's public key is invalid!");

// Bob computes the same shared secret from Alice's public key
let bob_shared = bob_secret.diffie_hellman(&alice_public)
    .expect("alice's public key is invalid!");

// Both participants arrive on the same shared secret
assert_eq!(alice_shared.as_bytes(), bob_shared.as_bytes());

Type Definitions

EphemeralSecret	feature="ecdh" NIST P-256 Ephemeral Diffie-Hellman Secret.
SharedSecret	feature="ecdh" Shared secret value computed via ECDH key agreement.