Rename CommitmentTreeWitness -> MerklePath

zcash_primitives/src/merkle_tree.rs

@@ -375,11 +375,11 @@ impl<Node: Hashable> IncrementalWitness<Node> {
     }
 
     /// Returns the current witness, or None if the tree is empty.
-    pub fn path(&self) -> Option<CommitmentTreeWitness<Node>> {
+    pub fn path(&self) -> Option<MerklePath<Node>> {
         self.path_inner(SAPLING_COMMITMENT_TREE_DEPTH)
     }
 
-    fn path_inner(&self, depth: usize) -> Option<CommitmentTreeWitness<Node>> {
+    fn path_inner(&self, depth: usize) -> Option<MerklePath<Node>> {
         let mut filler = self.filler();
         let mut auth_path = Vec::new();
 
@@ -406,31 +406,27 @@ impl<Node: Hashable> IncrementalWitness<Node> {
         }
         assert_eq!(auth_path.len(), depth);
 
-        Some(CommitmentTreeWitness::from_path(
-            auth_path,
-            self.position() as u64,
-        ))
+        Some(MerklePath::from_path(auth_path, self.position() as u64))
     }
 }
 
-/// A witness to a path from a position in a particular commitment tree to the root of
-/// that tree.
+/// A path from a position in a particular commitment tree to the root of that tree.
 #[derive(Clone, Debug, PartialEq)]
-pub struct CommitmentTreeWitness<Node: Hashable> {
+pub struct MerklePath<Node: Hashable> {
     pub auth_path: Vec<(Node, bool)>,
     pub position: u64,
 }
 
-impl<Node: Hashable> CommitmentTreeWitness<Node> {
-    /// Constructs a witness directly from its path and position.
+impl<Node: Hashable> MerklePath<Node> {
+    /// Constructs a Merkle path directly from a path and position.
     pub fn from_path(auth_path: Vec<(Node, bool)>, position: u64) -> Self {
-        CommitmentTreeWitness {
+        MerklePath {
             auth_path,
             position,
         }
     }
 
-    /// Reads a witness from its serialized form.
+    /// Reads a Merkle path from its serialized form.
     pub fn from_slice(witness: &[u8]) -> Result<Self, ()> {
         Self::from_slice_with_depth(witness, SAPLING_COMMITMENT_TREE_DEPTH)
     }
@@ -486,7 +482,7 @@ impl<Node: Hashable> CommitmentTreeWitness<Node> {
         // have provided more information than they should have, indicating
         // a bug downstream
         if witness.is_empty() {
-            Ok(CommitmentTreeWitness {
+            Ok(MerklePath {
                 auth_path,
                 position,
             })
@@ -495,7 +491,7 @@ impl<Node: Hashable> CommitmentTreeWitness<Node> {
         }
     }
 
-    /// Returns the root of the tree corresponding to the witness.
+    /// Returns the root of the tree corresponding to this path applied to `leaf`.
     pub fn root(&self, leaf: Node) -> Node {
         self.auth_path
             .iter()
@@ -512,7 +508,7 @@ impl<Node: Hashable> CommitmentTreeWitness<Node> {
 
 #[cfg(test)]
 mod tests {
-    use super::{CommitmentTree, CommitmentTreeWitness, Hashable, IncrementalWitness, PathFiller};
+    use super::{CommitmentTree, Hashable, IncrementalWitness, MerklePath, PathFiller};
     use crate::sapling::Node;
 
     use ff::PrimeFieldRepr;
@@ -611,7 +607,7 @@ mod tests {
             self.0.root_inner(TESTING_DEPTH)
         }
 
-        fn path(&self) -> Option<CommitmentTreeWitness<Node>> {
+        fn path(&self) -> Option<MerklePath<Node>> {
             self.0.path_inner(TESTING_DEPTH)
         }
     }
@@ -1047,7 +1043,7 @@ mod tests {
 
                 if let Some(leaf) = leaf {
                     let path = witness.path().expect("should be able to create a path");
-                    let expected = CommitmentTreeWitness::from_slice_with_depth(
+                    let expected = MerklePath::from_slice_with_depth(
                         &mut hex::decode(paths[paths_i]).unwrap(),
                         TESTING_DEPTH,
                     )

zcash_primitives/src/prover.rs

@@ -7,7 +7,7 @@ use crate::{
 use pairing::bls12_381::{Bls12, Fr};
 
 use crate::{
-    merkle_tree::CommitmentTreeWitness,
+    merkle_tree::MerklePath,
     redjubjub::{PublicKey, Signature},
     sapling::Node,
     transaction::components::{Amount, GROTH_PROOF_SIZE},
@@ -35,7 +35,7 @@ pub trait TxProver {
         ar: Fs,
         value: u64,
         anchor: Fr,
-        witness: CommitmentTreeWitness<Node>,
+        merkle_path: MerklePath<Node>,
     ) -> Result<
         (
             [u8; GROTH_PROOF_SIZE],
@@ -82,7 +82,7 @@ pub(crate) mod mock {
     };
 
     use crate::{
-        merkle_tree::CommitmentTreeWitness,
+        merkle_tree::MerklePath,
         redjubjub::{PublicKey, Signature},
         sapling::Node,
         transaction::components::{Amount, GROTH_PROOF_SIZE},
@@ -108,7 +108,7 @@ pub(crate) mod mock {
             ar: Fs,
             value: u64,
             _anchor: Fr,
-            _witness: CommitmentTreeWitness<Node>,
+            _merkle_path: MerklePath<Node>,
         ) -> Result<
             (
                 [u8; GROTH_PROOF_SIZE],

zcash_primitives/src/transaction/builder.rs

@@ -13,7 +13,7 @@ use crate::{
     consensus,
     keys::OutgoingViewingKey,
     legacy::TransparentAddress,
-    merkle_tree::CommitmentTreeWitness,
+    merkle_tree::MerklePath,
     note_encryption::{generate_esk, Memo, SaplingNoteEncryption},
     prover::TxProver,
     redjubjub::PrivateKey,
@@ -53,7 +53,7 @@ struct SpendDescriptionInfo {
     diversifier: Diversifier,
     note: Note<Bls12>,
     alpha: Fs,
-    witness: CommitmentTreeWitness<Node>,
+    merkle_path: MerklePath<Node>,
 }
 
 pub struct SaplingOutput {
@@ -334,24 +334,24 @@ impl<R: RngCore + CryptoRng> Builder<R> {
 
     /// Adds a Sapling note to be spent in this transaction.
     ///
-    /// Returns an error if the given witness does not have the same anchor as previous
-    /// witnesses, or has no path.
+    /// Returns an error if the given Merkle path does not have the same anchor as the
+    /// paths for previous Sapling notes.
     pub fn add_sapling_spend(
         &mut self,
         extsk: ExtendedSpendingKey,
         diversifier: Diversifier,
         note: Note<Bls12>,
-        witness: CommitmentTreeWitness<Node>,
+        merkle_path: MerklePath<Node>,
     ) -> Result<(), Error> {
         // Consistency check: all anchors must equal the first one
         let cm = Node::new(note.cm(&JUBJUB).into());
         if let Some(anchor) = self.anchor {
-            let witness_root: Fr = witness.root(cm).into();
-            if witness_root != anchor {
+            let path_root: Fr = merkle_path.root(cm).into();
+            if path_root != anchor {
                 return Err(Error::AnchorMismatch);
             }
         } else {
-            self.anchor = Some(witness.root(cm).into())
+            self.anchor = Some(merkle_path.root(cm).into())
         }
 
         let alpha = Fs::random(&mut self.rng);
@@ -363,7 +363,7 @@ impl<R: RngCore + CryptoRng> Builder<R> {
             diversifier,
             note,
             alpha,
-            witness,
+            merkle_path,
         });
 
         Ok(())
@@ -521,7 +521,7 @@ impl<R: RngCore + CryptoRng> Builder<R> {
                 let mut nullifier = [0u8; 32];
                 nullifier.copy_from_slice(&spend.note.nf(
                     &proof_generation_key.to_viewing_key(&JUBJUB),
-                    spend.witness.position,
+                    spend.merkle_path.position,
                     &JUBJUB,
                 ));
 
@@ -534,7 +534,7 @@ impl<R: RngCore + CryptoRng> Builder<R> {
                         spend.alpha,
                         spend.note.value,
                         anchor,
-                        spend.witness.clone(),
+                        spend.merkle_path.clone(),
                     )
                     .map_err(|()| Error::SpendProof)?;