kem: Made rng input a mut ref; made Error assoc type impl Debug

kem/src/lib.rs

@@ -9,23 +9,26 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs, unused_qualifications, missing_debug_implementations)]
 
+use core::fmt::Debug;
+use rand_core::CryptoRngCore;
+
 /// A value that can be encapsulated to. Often, this will just be a public key. However, it can
 /// also be a bundle of public keys, or it can include a sender's private key for authenticated
 /// encapsulation.
 pub trait Encapsulate<EK, SS> {
     /// Encapsulation error
-    type Error;
+    type Error: Debug;
 
     /// Encapsulates a fresh shared secret
-    fn encapsulate(&self, rng: impl rand_core::CryptoRngCore) -> Result<(EK, SS), Self::Error>;
+    fn encapsulate(&self, rng: &mut impl CryptoRngCore) -> Result<(EK, SS), Self::Error>;
 }
 
 /// A value that can be used to decapsulate an encapsulated key. Often, this will just be a secret
 /// key. But, as with [`Encapsulate`], it can be a bundle of secret keys, or it can include a
 /// sender's private key for authenticated encapsulation.
 pub trait Decapsulate<EK, SS> {
     /// Decapsulation error
-    type Error;
+    type Error: Debug;
 
     /// Decapsulates the given encapsulated key
     fn decapsulate(&self, encapsulated_key: &EK) -> Result<SS, Self::Error>;

kem/tests/hpke.rs

@@ -19,7 +19,7 @@ impl Encapsulate<EncappedKey, SharedSecret> for PublicKey {
 
     fn encapsulate(
         &self,
-        mut csprng: impl CryptoRngCore,
+        mut csprng: &mut impl CryptoRngCore,
     ) -> Result<(EncappedKey, SharedSecret), HpkeError> {
         <X25519HkdfSha256 as KemTrait>::encap(&self.0, None, &mut csprng).map(|(ek, ss)| (ss, ek))
     }

kem/tests/saber.rs

@@ -17,7 +17,7 @@ impl Encapsulate<SaberEncappedKey, SaberSharedSecret> for SaberPublicKey {
 
     fn encapsulate(
         &self,
-        _: impl CryptoRngCore,
+        _: &mut impl CryptoRngCore,
     ) -> Result<(SaberEncappedKey, SaberSharedSecret), ()> {
         let (ss, ek) = encapsulate(&self.0);
         Ok((ek, ss))

kem/tests/x3dh.rs

@@ -50,7 +50,7 @@ impl Encapsulate<EphemeralKey, SharedSecret> for EncapContext {
 
     fn encapsulate(
         &self,
-        _: impl CryptoRngCore,
+        _: &mut impl CryptoRngCore,
     ) -> Result<(EphemeralKey, SharedSecret), Self::Error> {
         // Make a new ephemeral key. This will be the encapped key
         let ek = EphemeralKey::default();