Address review comments

Author: AlfioEmanueleFresta

libwebauthn/src/transport/cable/advertisement.rs

@@ -19,8 +19,8 @@ pub(crate) struct DecryptedAdvert {
     pub encoded_tunnel_server_domain: u16,
 }
 
-impl From<&[u8]> for DecryptedAdvert {
-    fn from(plaintext: &[u8]) -> Self {
+impl From<[u8; 16]> for DecryptedAdvert {
+    fn from(plaintext: [u8; 16]) -> Self {
         let mut nonce = [0u8; 10];
         nonce.copy_from_slice(&plaintext[1..11]);
         let mut routing_id = [0u8; 3];
@@ -70,7 +70,7 @@ pub(crate) async fn await_advertisement(
         };
         trace!(?decrypted);
 
-        let advert = DecryptedAdvert::from(decrypted.as_slice());
+        let advert = DecryptedAdvert::from(decrypted);
         debug!(
             ?device,
             ?decrypted,

libwebauthn/src/transport/cable/crypto.rs

@@ -28,7 +28,7 @@ fn reserved_bits_are_zero(plaintext: &[u8]) -> bool {
 }
 
 #[instrument]
-pub fn trial_decrypt_advert(eid_key: &[u8], candidate_advert: &[u8]) -> Option<Vec<u8>> {
+pub fn trial_decrypt_advert(eid_key: &[u8], candidate_advert: &[u8]) -> Option<[u8; 16]> {
     if candidate_advert.len() != 20 {
         warn!("candidate advert is not 20 bytes");
         return None;
@@ -55,7 +55,9 @@ pub fn trial_decrypt_advert(eid_key: &[u8], candidate_advert: &[u8]) -> Option<V
         return None;
     }
 
-    Some(block.to_vec())
+    let mut plaintext = [0u8; 16];
+    plaintext.copy_from_slice(&block);
+    Some(plaintext)
 }
 
 #[cfg(test)]

libwebauthn/src/transport/cable/tunnel.rs

@@ -108,7 +108,7 @@ pub(crate) struct CableLinkingInfo {
     pub authenticator_public_key: Vec<u8>,
     /// User-friendly name of the authenticator
     pub authenticator_name: String,
-    /// HMAC of the handshake hash (Noise's channel binding value) usinng the
+    /// HMAC of the handshake hash (Noise's channel binding value) using the
     /// shared secret (link_secret) as key
     #[allow(dead_code)]
     pub handshake_signature: Vec<u8>,