Andrey Khmuro
2 years ago
8 changed files with 53 additions and 469 deletions
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+2 -0CHANGELOG.md
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+0 -1README.md
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+0 -3src/merkle/mod.rs
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+2 -0src/merkle/partial_mt/mod.rs
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+0 -408src/merkle/path_set.rs
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+9 -16src/merkle/store/mod.rs
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+38 -39src/merkle/store/tests.rs
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+2 -2src/utils/kv_map.rs
@ -1,408 +0,0 @@ |
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use super::{BTreeMap, MerkleError, MerklePath, NodeIndex, Rpo256, ValuePath, Vec};
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use crate::{hash::rpo::RpoDigest, Word};
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// MERKLE PATH SET
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// ================================================================================================
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/// A set of Merkle paths.
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct MerklePathSet {
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root: RpoDigest,
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total_depth: u8,
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paths: BTreeMap<u64, MerklePath>,
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}
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impl MerklePathSet {
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// CONSTRUCTOR
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// --------------------------------------------------------------------------------------------
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/// Returns an empty MerklePathSet.
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pub fn new(depth: u8) -> Self {
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let root = RpoDigest::default();
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let paths = BTreeMap::new();
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Self {
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root,
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total_depth: depth,
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paths,
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}
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}
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/// Appends the provided paths iterator into the set.
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///
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/// Analogous to `[Self::add_path]`.
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pub fn with_paths<I>(self, paths: I) -> Result<Self, MerkleError>
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where
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I: IntoIterator<Item = (u64, RpoDigest, MerklePath)>,
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{
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paths.into_iter().try_fold(self, |mut set, (index, value, path)| {
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set.add_path(index, value.into(), path)?;
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Ok(set)
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})
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}
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// PUBLIC ACCESSORS
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// --------------------------------------------------------------------------------------------
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/// Returns the root to which all paths in this set resolve.
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pub const fn root(&self) -> RpoDigest {
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self.root
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}
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/// Returns the depth of the Merkle tree implied by the paths stored in this set.
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///
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/// Merkle tree of depth 1 has two leaves, depth 2 has four leaves etc.
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pub const fn depth(&self) -> u8 {
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self.total_depth
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}
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/// Returns a node at the specified index.
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///
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/// # Errors
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/// Returns an error if:
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/// * The specified index is not valid for the depth of structure.
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/// * Requested node does not exist in the set.
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pub fn get_node(&self, index: NodeIndex) -> Result<RpoDigest, MerkleError> {
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if index.depth() != self.total_depth {
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return Err(MerkleError::InvalidDepth {
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expected: self.total_depth,
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provided: index.depth(),
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});
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}
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let parity = index.value() & 1;
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let path_key = index.value() - parity;
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self.paths
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.get(&path_key)
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.ok_or(MerkleError::NodeNotInSet(index))
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.map(|path| path[parity as usize])
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}
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/// Returns a leaf at the specified index.
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///
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/// # Errors
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/// * The specified index is not valid for the depth of the structure.
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/// * Leaf with the requested path does not exist in the set.
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pub fn get_leaf(&self, index: u64) -> Result<Word, MerkleError> {
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let index = NodeIndex::new(self.depth(), index)?;
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Ok(self.get_node(index)?.into())
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}
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/// Returns a Merkle path to the node at the specified index. The node itself is
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/// not included in the path.
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///
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/// # Errors
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/// Returns an error if:
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/// * The specified index is not valid for the depth of structure.
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/// * Node of the requested path does not exist in the set.
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pub fn get_path(&self, index: NodeIndex) -> Result<MerklePath, MerkleError> {
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if index.depth() != self.total_depth {
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return Err(MerkleError::InvalidDepth {
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expected: self.total_depth,
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provided: index.depth(),
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});
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}
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let parity = index.value() & 1;
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let path_key = index.value() - parity;
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let mut path =
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self.paths.get(&path_key).cloned().ok_or(MerkleError::NodeNotInSet(index))?;
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path.remove(parity as usize);
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Ok(path)
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}
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/// Returns all paths in this path set together with their indexes.
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pub fn to_paths(&self) -> Vec<(u64, ValuePath)> {
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let mut result = Vec::with_capacity(self.paths.len() * 2);
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for (&index, path) in self.paths.iter() {
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// push path for the even index into the result
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let path1 = ValuePath {
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value: path[0],
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path: MerklePath::new(path[1..].to_vec()),
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};
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result.push((index, path1));
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// push path for the odd index into the result
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let mut path2 = path.clone();
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let leaf2 = path2.remove(1);
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let path2 = ValuePath {
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value: leaf2,
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path: path2,
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};
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result.push((index + 1, path2));
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}
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result
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}
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// STATE MUTATORS
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// --------------------------------------------------------------------------------------------
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/// Adds the specified Merkle path to this [MerklePathSet]. The `index` and `value` parameters
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/// specify the leaf node at which the path starts.
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///
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/// # Errors
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/// Returns an error if:
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/// - The specified index is is not valid in the context of this Merkle path set (i.e., the
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/// index implies a greater depth than is specified for this set).
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/// - The specified path is not consistent with other paths in the set (i.e., resolves to a
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/// different root).
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pub fn add_path(
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&mut self,
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index_value: u64,
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value: Word,
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mut path: MerklePath,
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) -> Result<(), MerkleError> {
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let mut index = NodeIndex::new(path.len() as u8, index_value)?;
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if index.depth() != self.total_depth {
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return Err(MerkleError::InvalidDepth {
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expected: self.total_depth,
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provided: index.depth(),
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});
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}
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// update the current path
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let parity = index_value & 1;
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path.insert(parity as usize, value.into());
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// traverse to the root, updating the nodes
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let root = Rpo256::merge(&[path[0], path[1]]);
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let root = path.iter().skip(2).copied().fold(root, |root, hash| {
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index.move_up();
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Rpo256::merge(&index.build_node(root, hash))
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});
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// if the path set is empty (the root is all ZEROs), set the root to the root of the added
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// path; otherwise, the root of the added path must be identical to the current root
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if self.root == RpoDigest::default() {
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self.root = root;
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} else if self.root != root {
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return Err(MerkleError::ConflictingRoots([self.root, root].to_vec()));
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}
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// finish updating the path
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let path_key = index_value - parity;
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self.paths.insert(path_key, path);
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Ok(())
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}
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/// Replaces the leaf at the specified index with the provided value.
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///
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/// # Errors
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/// Returns an error if:
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/// * Requested node does not exist in the set.
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pub fn update_leaf(&mut self, base_index_value: u64, value: Word) -> Result<(), MerkleError> {
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let mut index = NodeIndex::new(self.depth(), base_index_value)?;
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let parity = index.value() & 1;
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let path_key = index.value() - parity;
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let path = match self.paths.get_mut(&path_key) {
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Some(path) => path,
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None => return Err(MerkleError::NodeNotInSet(index)),
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};
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// Fill old_hashes vector -----------------------------------------------------------------
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let mut current_index = index;
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let mut old_hashes = Vec::with_capacity(path.len().saturating_sub(2));
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let mut root = Rpo256::merge(&[path[0], path[1]]);
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for hash in path.iter().skip(2).copied() {
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old_hashes.push(root);
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current_index.move_up();
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let input = current_index.build_node(hash, root);
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root = Rpo256::merge(&input);
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}
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// Fill new_hashes vector -----------------------------------------------------------------
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path[index.is_value_odd() as usize] = value.into();
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let mut new_hashes = Vec::with_capacity(path.len().saturating_sub(2));
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let mut new_root = Rpo256::merge(&[path[0], path[1]]);
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for path_hash in path.iter().skip(2).copied() {
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new_hashes.push(new_root);
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index.move_up();
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let input = current_index.build_node(path_hash, new_root);
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new_root = Rpo256::merge(&input);
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}
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self.root = new_root;
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// update paths ---------------------------------------------------------------------------
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for path in self.paths.values_mut() {
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for i in (0..old_hashes.len()).rev() {
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if path[i + 2] == old_hashes[i] {
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path[i + 2] = new_hashes[i];
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break;
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}
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}
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}
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Ok(())
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}
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}
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// TESTS
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// ================================================================================================
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::merkle::{int_to_leaf, int_to_node};
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#[test]
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fn get_root() {
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let leaf0 = int_to_node(0);
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let leaf1 = int_to_node(1);
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let leaf2 = int_to_node(2);
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let leaf3 = int_to_node(3);
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let parent0 = calculate_parent_hash(leaf0, 0, leaf1);
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let parent1 = calculate_parent_hash(leaf2, 2, leaf3);
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let root_exp = calculate_parent_hash(parent0, 0, parent1);
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let set = super::MerklePathSet::new(2)
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.with_paths([(0, leaf0, vec![leaf1, parent1].into())])
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.unwrap();
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assert_eq!(set.root(), root_exp);
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}
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#[test]
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fn add_and_get_path() {
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let path_6 = vec![int_to_node(7), int_to_node(45), int_to_node(123)];
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let hash_6 = int_to_node(6);
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let index = 6_u64;
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let depth = 3_u8;
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let set = super::MerklePathSet::new(depth)
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.with_paths([(index, hash_6, path_6.clone().into())])
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.unwrap();
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let stored_path_6 = set.get_path(NodeIndex::make(depth, index)).unwrap();
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assert_eq!(path_6, *stored_path_6);
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}
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#[test]
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fn get_node() {
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let path_6 = vec![int_to_node(7), int_to_node(45), int_to_node(123)];
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let hash_6 = int_to_node(6);
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let index = 6_u64;
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let depth = 3_u8;
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let set = MerklePathSet::new(depth).with_paths([(index, hash_6, path_6.into())]).unwrap();
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assert_eq!(int_to_node(6u64), set.get_node(NodeIndex::make(depth, index)).unwrap());
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}
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#[test]
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fn update_leaf() {
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let hash_4 = int_to_node(4);
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let hash_5 = int_to_node(5);
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let hash_6 = int_to_node(6);
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let hash_7 = int_to_node(7);
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let hash_45 = calculate_parent_hash(hash_4, 12u64, hash_5);
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let hash_67 = calculate_parent_hash(hash_6, 14u64, hash_7);
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let hash_0123 = int_to_node(123);
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let path_6 = vec![hash_7, hash_45, hash_0123];
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let path_5 = vec![hash_4, hash_67, hash_0123];
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let path_4 = vec![hash_5, hash_67, hash_0123];
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let index_6 = 6_u64;
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let index_5 = 5_u64;
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let index_4 = 4_u64;
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let depth = 3_u8;
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let mut set = MerklePathSet::new(depth)
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.with_paths([
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(index_6, hash_6, path_6.into()),
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(index_5, hash_5, path_5.into()),
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(index_4, hash_4, path_4.into()),
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])
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.unwrap();
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let new_hash_6 = int_to_leaf(100);
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let new_hash_5 = int_to_leaf(55);
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set.update_leaf(index_6, new_hash_6).unwrap();
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let new_path_4 = set.get_path(NodeIndex::make(depth, index_4)).unwrap();
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let new_hash_67 = calculate_parent_hash(new_hash_6.into(), 14_u64, hash_7);
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assert_eq!(new_hash_67, new_path_4[1]);
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set.update_leaf(index_5, new_hash_5).unwrap();
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let new_path_4 = set.get_path(NodeIndex::make(depth, index_4)).unwrap();
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let new_path_6 = set.get_path(NodeIndex::make(depth, index_6)).unwrap();
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let new_hash_45 = calculate_parent_hash(new_hash_5.into(), 13_u64, hash_4);
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assert_eq!(new_hash_45, new_path_6[1]);
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assert_eq!(RpoDigest::from(new_hash_5), new_path_4[0]);
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}
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#[test]
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fn depth_3_is_correct() {
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let a = int_to_node(1);
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let b = int_to_node(2);
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let c = int_to_node(3);
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let d = int_to_node(4);
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let e = int_to_node(5);
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let f = int_to_node(6);
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let g = int_to_node(7);
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let h = int_to_node(8);
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let i = Rpo256::merge(&[a, b]);
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let j = Rpo256::merge(&[c, d]);
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let k = Rpo256::merge(&[e, f]);
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let l = Rpo256::merge(&[g, h]);
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let m = Rpo256::merge(&[i, j]);
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let n = Rpo256::merge(&[k, l]);
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let root = Rpo256::merge(&[m, n]);
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let mut set = MerklePathSet::new(3);
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let value = b;
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let index = 1;
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let path = MerklePath::new([a, j, n].to_vec());
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set.add_path(index, value.into(), path).unwrap();
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assert_eq!(*value, set.get_leaf(index).unwrap());
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assert_eq!(root, set.root());
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let value = e;
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let index = 4;
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let path = MerklePath::new([f, l, m].to_vec());
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set.add_path(index, value.into(), path).unwrap();
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assert_eq!(*value, set.get_leaf(index).unwrap());
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assert_eq!(root, set.root());
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let value = a;
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let index = 0;
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let path = MerklePath::new([b, j, n].to_vec());
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set.add_path(index, value.into(), path).unwrap();
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assert_eq!(*value, set.get_leaf(index).unwrap());
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assert_eq!(root, set.root());
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let value = h;
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let index = 7;
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let path = MerklePath::new([g, k, m].to_vec());
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set.add_path(index, value.into(), path).unwrap();
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assert_eq!(*value, set.get_leaf(index).unwrap());
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assert_eq!(root, set.root());
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}
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// HELPER FUNCTIONS
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// --------------------------------------------------------------------------------------------
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const fn is_even(pos: u64) -> bool {
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pos & 1 == 0
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}
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/// Calculates the hash of the parent node by two sibling ones
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/// - node — current node
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/// - node_pos — position of the current node
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/// - sibling — neighboring vertex in the tree
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fn calculate_parent_hash(node: RpoDigest, node_pos: u64, sibling: RpoDigest) -> RpoDigest {
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if is_even(node_pos) {
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Rpo256::merge(&[node, sibling])
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} else {
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Rpo256::merge(&[sibling, node])
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}
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}
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}
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