mirror of
https://github.com/arnaucube/miden-crypto.git
synced 2026-01-12 00:51:29 +01:00
bugfix: reverse merkle path to match other structures
The store builds the path from root to leaf, this updates the code to return a path from leaf to root, as it is done by the other structures. This also added custom error for missing root.
This commit is contained in:
Victor Lopez
361
src/merkle/store/mod.rs
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361
src/merkle/store/mod.rs
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@@ -0,0 +1,361 @@
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//! An in-memory data store for Merkle-lized data
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//!
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//! This is a in memory data store for Merkle trees, this store allows all the nodes of a tree
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//! (leaves or internal) to live as long as necessary and without duplication, this allows the
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//! implementation of efficient persistent data structures
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use super::{
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BTreeMap, BTreeSet, EmptySubtreeRoots, MerkleError, MerklePath, MerklePathSet, MerkleTree,
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NodeIndex, Rpo256, RpoDigest, SimpleSmt, Vec, Word,
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};
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#[cfg(test)]
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mod tests;
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#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
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pub struct Node {
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left: RpoDigest,
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right: RpoDigest,
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}
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#[derive(Debug, Clone, Eq, PartialEq)]
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pub struct MerkleStore {
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nodes: BTreeMap<RpoDigest, Node>,
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}
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impl Default for MerkleStore {
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fn default() -> Self {
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Self::new()
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}
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}
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impl MerkleStore {
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// CONSTRUCTORS
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// --------------------------------------------------------------------------------------------
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/// Creates an empty `MerkleStore` instance.
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pub fn new() -> MerkleStore {
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// pre-populate the store with the empty hashes
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let subtrees = EmptySubtreeRoots::empty_hashes(64);
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let nodes = subtrees
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.iter()
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.copied()
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.zip(subtrees.iter().skip(1).copied())
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.map(|(child, parent)| {
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(
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parent,
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Node {
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left: child,
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right: child,
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},
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)
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})
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.collect();
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MerkleStore { nodes }
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}
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/// Appends the provided merkle tree represented by its `leaves` to the set.
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pub fn with_merkle_tree<I>(mut self, leaves: I) -> Result<Self, MerkleError>
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where
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I: IntoIterator<Item = Word>,
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{
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self.add_merkle_tree(leaves)?;
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Ok(self)
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}
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/// Appends the provided sparse merkle tree represented by its `entries` to the set.
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pub fn with_sparse_merkle_tree<R, I>(mut self, entries: R) -> Result<Self, MerkleError>
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where
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R: IntoIterator<IntoIter = I>,
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I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
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{
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self.add_sparse_merkle_tree(entries)?;
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Ok(self)
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}
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/// Appends the provided merkle path set.
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pub fn with_merkle_path(
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mut self,
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index_value: u64,
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node: Word,
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path: MerklePath,
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) -> Result<Self, MerkleError> {
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self.add_merkle_path(index_value, node, path)?;
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Ok(self)
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}
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// PUBLIC ACCESSORS
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// --------------------------------------------------------------------------------------------
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/// Returns the node at `index` rooted on the tree `root`.
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///
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/// # Errors
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///
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/// This method can return the following errors:
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/// - `RootNotInStore` if the `root` is not present in the storage.
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/// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
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pub fn get_node(&self, root: Word, index: NodeIndex) -> Result<Word, MerkleError> {
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let mut hash: RpoDigest = root.into();
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// corner case: check the root is in the storage when called with index `NodeIndex::root()`
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self.nodes
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.get(&hash)
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.ok_or(MerkleError::RootNotInStore(hash.into()))?;
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for bit in index.bit_iterator().rev() {
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let node = self
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.nodes
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.get(&hash)
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.ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
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hash = if bit { node.right } else { node.left }
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}
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Ok(hash.into())
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}
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/// Returns the node at the specified `index` and its opening to the `root`.
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///
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/// The path starts at the sibling of the target leaf.
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///
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/// # Errors
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///
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/// This method can return the following errors:
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/// - `RootNotInStore` if the `root` is not present in the storage.
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/// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
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pub fn get_path(
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&self,
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root: Word,
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index: NodeIndex,
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) -> Result<(Word, MerklePath), MerkleError> {
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let mut hash: RpoDigest = root.into();
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let mut path = Vec::with_capacity(index.depth().into());
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// corner case: check the root is in the storage when called with index `NodeIndex::root()`
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self.nodes
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.get(&hash)
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.ok_or(MerkleError::RootNotInStore(hash.into()))?;
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for bit in index.bit_iterator().rev() {
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let node = self
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.nodes
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.get(&hash)
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.ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
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hash = if bit {
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path.push(node.left.into());
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node.right
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} else {
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path.push(node.right.into());
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node.left
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}
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}
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path.reverse();
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Ok((hash.into(), MerklePath::new(path)))
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}
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// STATE MUTATORS
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// --------------------------------------------------------------------------------------------
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/// Adds all the nodes of a Merkle tree represented by `leaves`.
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///
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/// This will instantiate a Merkle tree using `leaves` and include all the nodes into the
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/// storage.
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///
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/// # Errors
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///
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/// This method may return the following errors:
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/// - `DepthTooSmall` if leaves is empty or contains only 1 element
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/// - `NumLeavesNotPowerOfTwo` if the number of leaves is not a power-of-two
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pub fn add_merkle_tree<I>(&mut self, leaves: I) -> Result<Word, MerkleError>
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where
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I: IntoIterator<Item = Word>,
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{
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let leaves: Vec<_> = leaves.into_iter().collect();
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if leaves.len() < 2 {
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return Err(MerkleError::DepthTooSmall(leaves.len() as u8));
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}
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let layers = leaves.len().ilog2();
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let tree = MerkleTree::new(leaves)?;
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let mut depth = 0;
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let mut parent_offset = 1;
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let mut child_offset = 2;
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while depth < layers {
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let layer_size = 1usize << depth;
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for _ in 0..layer_size {
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// merkle tree is using level form representation, so left and right siblings are
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// next to each other
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let left = tree.nodes[child_offset];
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let right = tree.nodes[child_offset + 1];
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self.nodes.insert(
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tree.nodes[parent_offset].into(),
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Node {
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left: left.into(),
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right: right.into(),
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},
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);
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parent_offset += 1;
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child_offset += 2;
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}
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depth += 1;
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}
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Ok(tree.nodes[1])
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}
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/// Adds all the nodes of a Sparse Merkle tree represented by `entries`.
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///
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/// This will instantiate a Sparse Merkle tree using `entries` and include all the nodes into
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/// the storage.
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///
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/// # Errors
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///
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/// This will return `InvalidEntriesCount` if the length of `entries` is not `63`.
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pub fn add_sparse_merkle_tree<R, I>(&mut self, entries: R) -> Result<Word, MerkleError>
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where
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R: IntoIterator<IntoIter = I>,
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I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
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{
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let smt = SimpleSmt::new(SimpleSmt::MAX_DEPTH)?.with_leaves(entries)?;
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for branch in smt.store.branches.values() {
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let parent = Rpo256::merge(&[branch.left, branch.right]);
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self.nodes.insert(
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parent,
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Node {
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left: branch.left,
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right: branch.right,
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},
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);
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}
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Ok(smt.root())
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}
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/// Adds all the nodes of a Merkle path represented by `path`.
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///
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/// This will compute the sibling elements determined by the Merkle `path` and `node`, and
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/// include all the nodes into the storage.
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pub fn add_merkle_path(
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&mut self,
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index_value: u64,
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node: Word,
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path: MerklePath,
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) -> Result<Word, MerkleError> {
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let mut node = node;
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let mut index = NodeIndex::new(self.nodes.len() as u8, index_value);
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for sibling in path {
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let (left, right) = match index.is_value_odd() {
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true => (sibling, node),
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false => (node, sibling),
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};
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let parent = Rpo256::merge(&[left.into(), right.into()]);
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self.nodes.insert(
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parent,
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Node {
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left: left.into(),
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right: right.into(),
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},
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);
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index.move_up();
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node = parent.into();
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}
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Ok(node)
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}
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/// Adds all the nodes of multiple Merkle paths into the store.
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///
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/// This will compute the sibling elements for each Merkle `path` and include all the nodes
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/// into the storage.
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///
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/// # Errors
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///
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/// Every path must resolve to the same root, otherwise this will return an `ConflictingRoots`
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/// error.
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pub fn add_merkle_paths<I>(&mut self, paths: I) -> Result<Word, MerkleError>
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where
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I: IntoIterator<Item = (u64, Word, MerklePath)>,
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{
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let paths: Vec<(u64, Word, MerklePath)> = paths.into_iter().collect();
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let roots: BTreeSet<RpoDigest> = paths
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.iter()
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.map(|(index, node, path)| path.compute_root(*index, *node).into())
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.collect();
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if roots.len() != 1 {
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return Err(MerkleError::ConflictingRoots(
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roots.iter().map(|v| Word::from(*v)).collect(),
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));
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}
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for (index_value, node, path) in paths {
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self.add_merkle_path(index_value, node, path)?;
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}
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Ok(roots.iter().next().unwrap().into())
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}
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/// Appends the provided [MerklePathSet] into the store.
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pub fn add_merkle_path_set(&mut self, path_set: &MerklePathSet) -> Result<Word, MerkleError> {
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let root = path_set.root();
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path_set.indexes().try_fold(root, |_, index| {
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let node = path_set.get_node(index)?;
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let path = path_set.get_path(index)?;
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self.add_merkle_path(index.value(), node, path)
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})
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}
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/// Sets a node to `value`.
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///
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/// # Errors
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///
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/// This method can return the following errors:
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/// - `RootNotInStore` if the `root` is not present in the storage.
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/// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
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pub fn set_node(
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&mut self,
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root: Word,
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index: NodeIndex,
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value: Word,
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) -> Result<Word, MerkleError> {
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let result = self.get_path(root, index)?;
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if result.0 != value {
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self.add_merkle_path(index.value(), value, result.1)
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} else {
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Ok(root)
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}
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}
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pub fn merge_roots(&mut self, root1: Word, root2: Word) -> Result<Word, MerkleError> {
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let root1: RpoDigest = root1.into();
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let root2: RpoDigest = root2.into();
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if !self.nodes.contains_key(&root1) {
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Err(MerkleError::NodeNotInStore(
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root1.into(),
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NodeIndex::new(0, 0),
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))
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} else if !self.nodes.contains_key(&root1) {
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Err(MerkleError::NodeNotInStore(
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root2.into(),
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NodeIndex::new(0, 0),
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))
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} else {
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let parent: Word = Rpo256::merge(&[root1, root2]).into();
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self.nodes.insert(
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parent.into(),
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Node {
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left: root1,
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right: root2,
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},
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);
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Ok(parent)
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}
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}
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}
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