feat: add X448 key exchange and Ed448 signatures

Cargo.toml

@@ -26,6 +26,7 @@ der = { version = "0.8", default-features = false }
 digest = { version = "0.11", default-features = false }
 ecdsa = { version = "0.17", default-features = false, features = ["alloc"] }
 ed25519-dalek = { version = "3", default-features = false, features = ["pkcs8"] }
+ed448-goldilocks = { version = "0.14.0-pre.15", default-features = false, features = ["pkcs8", "signing"] }
 getrandom = { version = "0.4", default-features = false, features = ["sys_rng"] }
 hmac = { version = "0.13", default-features = false }
 p256 = { version = "0.14", default-features = false, features = ["pem", "ecdsa", "ecdh"] }
@@ -39,6 +40,7 @@ sec1 = { version = "0.8", default-features = false }
 sha2 = { version = "0.11", default-features = false }
 signature = { version = "3", default-features = false }
 x25519-dalek = { version = "3", default-features = false }
+x448 = { version = "0.14.0-pre.12", default-features = false }
 
 [features]
 default = ["std", "tls12", "zeroize"]
@@ -51,5 +53,5 @@ tls12 = ["rustls/tls12"]
 # TODO: go through all of these that what gets exposed re: std error type
 std = ["alloc", "pki-types/std", "rustls/std"]
 # TODO: go through all of these to ensure to_vec etc. impls are exposed
-alloc = ["pki-types/alloc", "aead/alloc", "ed25519-dalek/alloc"]
+alloc = ["pki-types/alloc", "aead/alloc", "ed25519-dalek/alloc", "ed448-goldilocks/alloc"]
 zeroize = ["ed25519-dalek/zeroize", "x25519-dalek/zeroize"]

src/kx.rs

@@ -49,6 +49,49 @@ impl crypto::ActiveKeyExchange for X25519KeyExchange {
     }
 }
 
+#[derive(Debug)]
+pub struct X448;
+
+impl crypto::SupportedKxGroup for X448 {
+    fn name(&self) -> rustls::NamedGroup {
+        rustls::NamedGroup::X448
+    }
+
+    fn start(&self) -> Result<Box<dyn crypto::ActiveKeyExchange>, rustls::Error> {
+        let mut rng = UnwrapErr(getrandom::SysRng);
+        let priv_key = x448::EphemeralSecret::try_generate_from_rng(&mut rng)
+            .map_err(|_| rustls::Error::from(rustls::PeerMisbehaved::InvalidKeyShare))?;
+        let pub_key = x448::PublicKey::from(&priv_key);
+        Ok(Box::new(X448KeyExchange { priv_key, pub_key }))
+    }
+}
+
+pub struct X448KeyExchange {
+    priv_key: x448::EphemeralSecret,
+    pub_key: x448::PublicKey,
+}
+
+impl crypto::ActiveKeyExchange for X448KeyExchange {
+    fn complete(self: Box<X448KeyExchange>, peer: &[u8]) -> Result<SharedSecret, rustls::Error> {
+        let peer_pub = x448::PublicKey::from_bytes(peer)
+            .ok_or_else(|| rustls::Error::from(rustls::PeerMisbehaved::InvalidKeyShare))?;
+        Ok(self
+            .priv_key
+            .diffie_hellman(&peer_pub)
+            .as_bytes()
+            .as_slice()
+            .into())
+    }
+
+    fn pub_key(&self) -> &[u8] {
+        self.pub_key.as_bytes()
+    }
+
+    fn group(&self) -> rustls::NamedGroup {
+        X448.name()
+    }
+}
+
 macro_rules! impl_kx {
     ($name:ident, $kx_name:ty, $secret:ty, $public_key:ty) => {
         paste! {
@@ -109,4 +152,4 @@ macro_rules! impl_kx {
 impl_kx! {SecP256R1, rustls::NamedGroup::secp256r1, p256::ecdh::EphemeralSecret, p256::PublicKey}
 impl_kx! {SecP384R1, rustls::NamedGroup::secp384r1, p384::ecdh::EphemeralSecret, p384::PublicKey}
 
-pub const ALL_KX_GROUPS: &[&dyn SupportedKxGroup] = &[&X25519, &SecP256R1, &SecP384R1];
+pub const ALL_KX_GROUPS: &[&dyn SupportedKxGroup] = &[&X448, &X25519, &SecP256R1, &SecP384R1];