Expose RedPallas rerandomization

src/keys.rs

@@ -109,6 +109,13 @@ impl From<&SpendAuthorizingKey> for SpendValidatingKey {
     }
 }
 
+impl SpendValidatingKey {
+    /// Randomizes this spend validating key with the given `randomizer`.
+    pub fn randomize(&self, randomizer: &pallas::Scalar) -> redpallas::VerificationKey<SpendAuth> {
+        self.0.randomize(randomizer)
+    }
+}
+
 /// A key used to derive [`Nullifier`]s from [`Note`]s.
 ///
 /// Defined in [Zcash Protocol Spec § 4.2.3: Orchard Key Components][orchardkeycomponents].

src/primitives/redpallas.rs

@@ -2,6 +2,8 @@
 
 use std::convert::{TryFrom, TryInto};
 
+use pasta_curves::pallas;
+
 /// A RedPallas signature type.
 pub trait SigType: reddsa::SigType + private::Sealed {}
 
@@ -73,6 +75,15 @@ impl<T: SigType> PartialEq for VerificationKey<T> {
     }
 }
 
+impl VerificationKey<SpendAuth> {
+    /// Randomizes this verification key with the given `randomizer`.
+    ///
+    /// Randomization is only supported for `SpendAuth` keys.
+    pub fn randomize(&self, randomizer: &pallas::Scalar) -> Self {
+        VerificationKey(self.0.randomize(randomizer))
+    }
+}
+
 /// A RedPallas signature.
 #[derive(Debug)]
 pub struct Signature<T: SigType>(reddsa::Signature<T>);