zcash_primitives: Add some more `Clone` and `Debug` impls

zcash_primitives/CHANGELOG.md

@@ -12,6 +12,7 @@ and this library adheres to Rust's notion of
   - `circuit` module (moved from `zcash_proofs::circuit::sapling`).
   - `constants` module.
   - `prover::{SpendProver, OutputProver}`
+  - `impl Debug for keys::{ExpandedSpendingKey, ProofGenerationKey}`
 - Test helpers, behind the `test-dependencies` feature flag:
   - `zcash_primitives::prover::mock::{MockSpendProver, MockOutputProver}`
 

zcash_primitives/src/sapling/circuit.rs

@@ -1,5 +1,7 @@
 //! The Sapling circuits.
 
+use core::fmt;
+
 use group::{ff::PrimeField, Curve};
 
 use bellman::{Circuit, ConstraintSystem, SynthesisError};
@@ -46,6 +48,7 @@ impl ValueCommitmentOpening {
 }
 
 /// This is an instance of the `Spend` circuit.
+#[derive(Clone)]
 pub struct Spend {
     /// The opening of a Pedersen commitment to the value being spent.
     pub value_commitment_opening: Option<ValueCommitmentOpening>,
@@ -71,7 +74,16 @@ pub struct Spend {
     pub anchor: Option<bls12_381::Scalar>,
 }
 
+impl fmt::Debug for Spend {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Spend")
+            .field("anchor", &self.anchor)
+            .finish_non_exhaustive()
+    }
+}
+
 /// This is an output circuit instance.
+#[derive(Clone)]
 pub struct Output {
     /// The opening of a Pedersen commitment to the value being spent.
     pub value_commitment_opening: Option<ValueCommitmentOpening>,
@@ -86,6 +98,12 @@ pub struct Output {
     pub esk: Option<jubjub::Fr>,
 }
 
+impl fmt::Debug for Output {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Output").finish_non_exhaustive()
+    }
+}
+
 /// Exposes a Pedersen commitment to the value as an
 /// input to the circuit
 fn expose_value_commitment<CS>(

zcash_primitives/src/sapling/keys.rs

@@ -4,6 +4,7 @@
 //!
 //! [section 4.2.2]: https://zips.z.cash/protocol/protocol.pdf#saplingkeycomponents
 
+use std::fmt;
 use std::io::{self, Read, Write};
 
 use super::{
@@ -46,6 +47,13 @@ pub struct ExpandedSpendingKey {
     pub ovk: OutgoingViewingKey,
 }
 
+impl fmt::Debug for ExpandedSpendingKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ExpandedSpendingKey")
+            .finish_non_exhaustive()
+    }
+}
+
 impl ExpandedSpendingKey {
     pub fn from_spending_key(sk: &[u8]) -> Self {
         let ask = jubjub::Fr::from_bytes_wide(prf_expand(sk, &[0x00]).as_array());
@@ -119,6 +127,14 @@ pub struct ProofGenerationKey {
     pub nsk: jubjub::Fr,
 }
 
+impl fmt::Debug for ProofGenerationKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ProofGenerationKey")
+            .field("ak", &self.ak)
+            .finish_non_exhaustive()
+    }
+}
+
 impl ProofGenerationKey {
     pub fn to_viewing_key(&self) -> ViewingKey {
         ViewingKey {
@@ -473,16 +489,9 @@ impl SharedSecret {
 pub mod testing {
     use proptest::collection::vec;
     use proptest::prelude::*;
-    use std::fmt::{self, Debug, Formatter};
 
     use super::{ExpandedSpendingKey, FullViewingKey, SaplingIvk};
 
-    impl Debug for ExpandedSpendingKey {
-        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-            write!(f, "Spending keys cannot be Debug-formatted.")
-        }
-    }
-
     prop_compose! {
         pub fn arb_expanded_spending_key()(v in vec(any::<u8>(), 32..252)) -> ExpandedSpendingKey {
             ExpandedSpendingKey::from_spending_key(&v)