refactor: refactor crypto APIs to use RpoDigest instead of Word

src/merkle/path.rs

@@ -1,4 +1,4 @@
-use super::{vec, InnerNodeInfo, MerkleError, NodeIndex, Rpo256, Vec, Word};
+use super::{vec, InnerNodeInfo, MerkleError, NodeIndex, Rpo256, RpoDigest, Vec};
 use core::ops::{Deref, DerefMut};
 
 // MERKLE PATH
@@ -7,7 +7,7 @@ use core::ops::{Deref, DerefMut};
 /// A merkle path container, composed of a sequence of nodes of a Merkle tree.
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct MerklePath {
-    nodes: Vec<Word>,
+    nodes: Vec<RpoDigest>,
 }
 
 impl MerklePath {
@@ -15,7 +15,7 @@ impl MerklePath {
     // --------------------------------------------------------------------------------------------
 
     /// Creates a new Merkle path from a list of nodes.
-    pub fn new(nodes: Vec<Word>) -> Self {
+    pub fn new(nodes: Vec<RpoDigest>) -> Self {
         Self { nodes }
     }
 
@@ -28,13 +28,13 @@ impl MerklePath {
     }
 
     /// Computes the merkle root for this opening.
-    pub fn compute_root(&self, index: u64, node: Word) -> Result<Word, MerkleError> {
+    pub fn compute_root(&self, index: u64, node: RpoDigest) -> Result<RpoDigest, MerkleError> {
         let mut index = NodeIndex::new(self.depth(), index)?;
         let root = self.nodes.iter().copied().fold(node, |node, sibling| {
             // compute the node and move to the next iteration.
-            let input = index.build_node(node.into(), sibling.into());
+            let input = index.build_node(node, sibling);
             index.move_up();
-            Rpo256::merge(&input).into()
+            Rpo256::merge(&input)
         });
         Ok(root)
     }
@@ -42,7 +42,7 @@ impl MerklePath {
     /// Verifies the Merkle opening proof towards the provided root.
     ///
     /// Returns `true` if `node` exists at `index` in a Merkle tree with `root`.
-    pub fn verify(&self, index: u64, node: Word, root: &Word) -> bool {
+    pub fn verify(&self, index: u64, node: RpoDigest, root: &RpoDigest) -> bool {
         match self.compute_root(index, node) {
             Ok(computed_root) => root == &computed_root,
             Err(_) => false,
@@ -55,7 +55,11 @@ impl MerklePath {
     ///
     /// # Errors
     /// Returns an error if the specified index is not valid for this path.
-    pub fn inner_nodes(&self, index: u64, node: Word) -> Result<InnerNodeIterator, MerkleError> {
+    pub fn inner_nodes(
+        &self,
+        index: u64,
+        node: RpoDigest,
+    ) -> Result<InnerNodeIterator, MerkleError> {
         Ok(InnerNodeIterator {
             nodes: &self.nodes,
             index: NodeIndex::new(self.depth(), index)?,
@@ -64,8 +68,8 @@ impl MerklePath {
     }
 }
 
-impl From<Vec<Word>> for MerklePath {
-    fn from(path: Vec<Word>) -> Self {
+impl From<Vec<RpoDigest>> for MerklePath {
+    fn from(path: Vec<RpoDigest>) -> Self {
         Self::new(path)
     }
 }
@@ -73,7 +77,7 @@ impl From<Vec<Word>> for MerklePath {
 impl Deref for MerklePath {
     // we use `Vec` here instead of slice so we can call vector mutation methods directly from the
     // merkle path (example: `Vec::remove`).
-    type Target = Vec<Word>;
+    type Target = Vec<RpoDigest>;
 
     fn deref(&self) -> &Self::Target {
         &self.nodes
@@ -89,15 +93,15 @@ impl DerefMut for MerklePath {
 // ITERATORS
 // ================================================================================================
 
-impl FromIterator<Word> for MerklePath {
-    fn from_iter<T: IntoIterator<Item = Word>>(iter: T) -> Self {
+impl FromIterator<RpoDigest> for MerklePath {
+    fn from_iter<T: IntoIterator<Item = RpoDigest>>(iter: T) -> Self {
         Self::new(iter.into_iter().collect())
     }
 }
 
 impl IntoIterator for MerklePath {
-    type Item = Word;
-    type IntoIter = vec::IntoIter<Word>;
+    type Item = RpoDigest;
+    type IntoIter = vec::IntoIter<RpoDigest>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.nodes.into_iter()
@@ -106,9 +110,9 @@ impl IntoIterator for MerklePath {
 
 /// An iterator over internal nodes of a [MerklePath].
 pub struct InnerNodeIterator<'a> {
-    nodes: &'a Vec<Word>,
+    nodes: &'a Vec<RpoDigest>,
     index: NodeIndex,
-    value: Word,
+    value: RpoDigest,
 }
 
 impl<'a> Iterator for InnerNodeIterator<'a> {
@@ -123,7 +127,7 @@ impl<'a> Iterator for InnerNodeIterator<'a> {
                 (self.value, self.nodes[sibling_pos])
             };
 
-            self.value = Rpo256::merge(&[left.into(), right.into()]).into();
+            self.value = Rpo256::merge(&[left, right]);
             self.index.move_up();
 
             Some(InnerNodeInfo {
@@ -144,7 +148,7 @@ impl<'a> Iterator for InnerNodeIterator<'a> {
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct ValuePath {
     /// The node value opening for `path`.
-    pub value: Word,
+    pub value: RpoDigest,
     /// The path from `value` to `root` (exclusive).
     pub path: MerklePath,
 }
@@ -156,7 +160,7 @@ pub struct ValuePath {
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct RootPath {
     /// The node value opening for `path`.
-    pub root: Word,
+    pub root: RpoDigest,
     /// The path from `value` to `root` (exclusive).
     pub path: MerklePath,
 }