ctap2-proto: Add authenticator::client_pin::raw::PublicKey type for deserialization

The cosey::PublicKey type does not properly implement deserialize for
the general PublicKey type. the client_pin::raw::PublicKey type is used
as an intermediate to allow deserialization of COSE public keys in the
client_pin protocol.

crates/ctap2-proto/src/authenticator/client_pin/mod.rs

@@ -7,6 +7,9 @@ use serde::{Deserialize, Serialize};
 
 pub mod auth_protocol;
 
+#[cfg(feature = "serde")]
+mod raw;
+
 pub type PinUvAuthParam = [u8; 16];
 
 

crates/ctap2-proto/src/authenticator/client_pin/raw/mod.rs

@@ -0,0 +1,6 @@
+//! Used to make serialization and deseriazation of the request and response
+//! possible in CBOR format while maintaining ergonomic enum variants for public
+//! API.
+
+mod public_key;
+

crates/ctap2-proto/src/authenticator/client_pin/raw/public_key.rs

@@ -0,0 +1,32 @@
+use cosey::{EcdhEsHkdf256PublicKey, Ed25519PublicKey, P256PublicKey};
+
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
+#[serde(untagged)]
+pub(crate) enum PublicKey {
+    P256Key(P256PublicKey),
+    EcdhEsHkdf256Key(EcdhEsHkdf256PublicKey),
+    Ed25519Key(Ed25519PublicKey),
+}
+
+impl Into<cosey::PublicKey> for PublicKey {
+    fn into(self) -> cosey::PublicKey {
+        match self {
+            PublicKey::P256Key(key) => cosey::PublicKey::P256Key(key),
+            PublicKey::EcdhEsHkdf256Key(key) => cosey::PublicKey::EcdhEsHkdf256Key(key),
+            PublicKey::Ed25519Key(key) => cosey::PublicKey::Ed25519Key(key),
+        }
+    }
+}
+
+pub(crate) fn deserialize<'de, D>(deserializer: D) -> Result<Option<cosey::PublicKey>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    PublicKey::deserialize(deserializer)
+        .map(Into::into)
+        .map(Some)
+}
+