Module agreement

Key Agreement: ECDH, including X25519.

Example

Note that this example uses X25519, but ECDH using NIST P-256/P-384 is done exactly the same way, just substituting agreement::ECDH_P256/agreement::ECDH_P384 for agreement::X25519.

use ring::{agreement, rand};

let rng = rand::SystemRandom::new();

let my_private_key = agreement::EphemeralPrivateKey::generate(&agreement::X25519, &rng)?;

// Make `my_public_key` a byte slice containing my public key. In a real
// application, this would be sent to the peer in an encoded protocol
// message.
let my_public_key = my_private_key.compute_public_key()?;

let peer_public_key = {
    // In a real application, the peer public key would be parsed out of a
    // protocol message. Here we just generate one.
    let peer_public_key = {
        let peer_private_key =
            agreement::EphemeralPrivateKey::generate(&agreement::X25519, &rng)?;
        peer_private_key.compute_public_key()?
    };

    agreement::UnparsedPublicKey::new(&agreement::X25519, peer_public_key)
};

agreement::agree_ephemeral(
    my_private_key,
    &peer_public_key,
    |_key_material| {
        // In a real application, we'd apply a KDF to the key material and the
        // public keys (as recommended in RFC 7748) and then derive session
        // keys from the result. We omit all that here.
    },
)?;

Structs

• Algorithm
  A key agreement algorithm.
• EphemeralPrivateKey
  An ephemeral private key for use (only) with agree_ephemeral. The signature of agree_ephemeral ensures that an EphemeralPrivateKey can be used for at most one key agreement.
• PublicKey
  A public key for key agreement.
• UnparsedPublicKey
  An unparsed, possibly malformed, public key for key agreement.

Statics

• ECDH_P256
  ECDH using the NSA Suite B P-256 (secp256r1) curve.
• ECDH_P384
  ECDH using the NSA Suite B P-384 (secp384r1) curve.
• X25519
  X25519 (ECDH using Curve25519) as described in RFC 7748.

Functions

• agree_ephemeral
  Performs a key agreement with an ephemeral private key and the given public key.