Rework Recipient to wrap p256::PublicKey

src/p256.rs

@@ -1,6 +1,5 @@
 use bech32::{ToBase32, Variant};
-use elliptic_curve::sec1::EncodedPoint;
-use p256::NistP256;
+use elliptic_curve::sec1::{FromEncodedPoint, ToEncodedPoint};
 use sha2::{Digest, Sha256};
 use std::convert::TryInto;
 use std::fmt;
@@ -11,11 +10,11 @@ pub(crate) const TAG_BYTES: usize = 4;
 
 /// Wrapper around a compressed secp256r1 curve point.
 #[derive(Clone)]
-pub struct Recipient(EncodedPoint<NistP256>);
+pub struct Recipient(p256::PublicKey);
 
 impl fmt::Debug for Recipient {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Recipient({:?})", self.as_bytes())
+        write!(f, "Recipient({:?})", self.to_encoded().as_bytes())
     }
 }
 
@@ -24,7 +23,7 @@ impl fmt::Display for Recipient {
         f.write_str(
             bech32::encode(
                 RECIPIENT_PREFIX,
-                self.as_bytes().to_base32(),
+                self.to_encoded().as_bytes().to_base32(),
                 Variant::Bech32,
             )
             .expect("HRP is valid")
@@ -34,22 +33,17 @@ impl fmt::Display for Recipient {
 }
 
 impl Recipient {
-    /// Attempts to parse a valid secp256r1 public key from its SEC-1 encoding.
-    pub(crate) fn from_pubkey(pubkey: EncodedPoint<NistP256>) -> Option<Self> {
-        if pubkey.is_compressed() {
-            if pubkey.decompress().is_some().into() {
-                Some(Recipient(pubkey))
-            } else {
-                None
-            }
-        } else {
-            Some(Recipient(pubkey.compress()))
-        }
+    /// Attempts to parse a valid YubiKey recipient from its SEC-1 encoding.
+    ///
+    /// This accepts both compressed (as used by the plugin) and uncompressed (as used in
+    /// the YubiKey certificate) encodings.
+    pub(crate) fn from_encoded(encoded: &p256::EncodedPoint) -> Option<Self> {
+        p256::PublicKey::from_encoded_point(&encoded).map(Recipient)
     }
 
-    /// Returns the compressed SEC-1 encoding of this public key.
-    pub(crate) fn as_bytes(&self) -> &[u8] {
-        self.0.as_bytes()
+    /// Returns the compressed SEC-1 encoding of this recipient.
+    pub(crate) fn to_encoded(&self) -> p256::EncodedPoint {
+        self.0.to_encoded_point(true)
     }
 
     pub(crate) fn tag(&self) -> [u8; TAG_BYTES] {