Added sk_to_pk() for Kem trait and implemented for dhkem (#40)

rozbb · Mar 19, 2023 · bef12c5 · bef12c5
1 parent 1232a8f
commit bef12c5
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/src/kem.rs b/src/kem.rs
@@ -48,6 +48,9 @@ pub trait Kem: Sized {
     #[cfg(not(feature = "serde_impls"))]
     type PrivateKey: Clone + PartialEq + Eq + Serializable + Deserializable;
 
+    /// Computes the public key of a given private key
+    fn sk_to_pk(sk: &Self::PrivateKey) -> Self::PublicKey;
+
     /// The encapsulated key for this KEM. This is used by the recipient to derive the shared
     /// secret.
     #[cfg(feature = "serde_impls")]

diff --git a/src/kem/dhkem.rs b/src/kem/dhkem.rs
@@ -114,7 +114,7 @@ macro_rules! impl_dhkem {
 
                 // The encapped key is the ephemeral pubkey
                 let encapped_key = {
-                    let pk_eph = <$dhkex as DhKeyExchange>::sk_to_pk(&sk_eph);
+                    let pk_eph = <$kem_name as KemTrait>::sk_to_pk(&sk_eph);
                     EncappedKey(pk_eph)
                 };
 
@@ -212,6 +212,11 @@ macro_rules! impl_dhkem {
                     <$dhkex as DhKeyExchange>::derive_keypair::<$kdf>(&suite_id, ikm)
                 }
 
+                /// Computes the public key of a given private key
+                fn sk_to_pk(sk: &PrivateKey) -> PublicKey {
+                    <$dhkex as DhKeyExchange>::sk_to_pk(sk)
+                }
+
                 // Runs encap_with_eph using a random ephemeral key
                 fn encap<R: CryptoRng + RngCore>(
                     pk_recip: &Self::PublicKey,