Split out Classic McEliece code in tuncfg-server example

1 files changed, 16 insertions, 7 deletions

diff --git a/talpid-tunnel-config-client/examples/tuncfg-server.rs b/talpid-tunnel-config-client/examples/tuncfg-server.rs
index 1c4c55d878..4ba996431c 100644
--- a/talpid-tunnel-config-client/examples/tuncfg-server.rs
+++ b/talpid-tunnel-config-client/examples/tuncfg-server.rs
@@ -5,7 +5,6 @@
 mod proto {
     tonic::include_proto!("ephemeralpeer");
 }
-use classic_mceliece_rust::{PublicKey, CRYPTO_PUBLICKEYBYTES};
 use proto::{
     ephemeral_peer_server::{EphemeralPeer, EphemeralPeerServer},
     EphemeralPeerRequestV1, EphemeralPeerResponseV1, PostQuantumResponseV1,
@@ -45,12 +44,7 @@ impl EphemeralPeer for EphemeralPeerImpl {
                 println!("\tKEM algorithm: {}", kem_pubkey.algorithm_name);
                 let (ciphertext, shared_secret) = match kem_pubkey.algorithm_name.as_str() {
                     "Classic-McEliece-460896f-round3" => {
-                        let key_data: [u8; CRYPTO_PUBLICKEYBYTES] =
-                            kem_pubkey.key_data.as_slice().try_into().unwrap();
-                        let public_key = PublicKey::from(&key_data);
-                        let (ciphertext, shared_secret) =
-                            classic_mceliece_rust::encapsulate_boxed(&public_key, &mut rng);
-                        (ciphertext.as_array().to_vec(), *shared_secret.as_array())
+                        encapsulate_classic_mceliece(kem_pubkey.key_data.as_slice(), &mut rng)
                     }
                     "ML-KEM-1024" => encapsulate_ml_kem(kem_pubkey.key_data.as_slice(), &mut rng),
                     name => panic!("Unsupported KEM algorithm: {name}"),
@@ -80,6 +74,21 @@ impl EphemeralPeer for EphemeralPeerImpl {
 /// Generate a random shared secret and encapsulate it with the given
 /// public key/encapsulation key. Returns the ciphertext to return
 /// to the owner of the public key, along with the shared secret.
+fn encapsulate_classic_mceliece<R: RngCore + CryptoRng>(
+    public_key: &[u8],
+    rng: &mut R,
+) -> (Vec<u8>, [u8; 32]) {
+    use classic_mceliece_rust::{PublicKey, CRYPTO_PUBLICKEYBYTES};
+
+    let public_key_array = <[u8; CRYPTO_PUBLICKEYBYTES]>::try_from(public_key).unwrap();
+    let public_key = PublicKey::from(&public_key_array);
+    let (ciphertext, shared_secret) = classic_mceliece_rust::encapsulate_boxed(&public_key, rng);
+    (ciphertext.as_array().to_vec(), *shared_secret.as_array())
+}
+
+/// Generate a random shared secret and encapsulate it with the given
+/// public key/encapsulation key. Returns the ciphertext to return
+/// to the owner of the public key, along with the shared secret.
 fn encapsulate_ml_kem<R: RngCore + CryptoRng>(
     public_key: &[u8],
     rng: &mut R,