miden-crypto/src/merkle/store/mod.rs
src/merkle/store/mod.rsRaw
1use super::{
2 BTreeMap, BTreeSet, EmptySubtreeRoots, MerkleError, MerklePath, MerklePathSet, MerkleTree,
3 NodeIndex, RootPath, Rpo256, RpoDigest, SimpleSmt, ValuePath, Vec, Word,
4};
5use crate::utils::{ByteReader, ByteWriter, Deserializable, DeserializationError, Serializable};
6
7#[cfg(test)]
8mod tests;
9
10#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
11pub struct Node {
12 left: RpoDigest,
13 right: RpoDigest,
14}
15
16/// An in-memory data store for Merkle-lized data.
17///
18/// This is a in memory data store for Merkle trees, this store allows all the nodes of multiple
19/// trees to live as long as necessary and without duplication, this allows the implementation of
20/// space efficient persistent data structures.
21///
22/// Example usage:
23///
24/// ```rust
25/// # use miden_crypto::{ZERO, Felt, Word};
26/// # use miden_crypto::merkle::{NodeIndex, MerkleStore, MerkleTree};
27/// # use miden_crypto::hash::rpo::Rpo256;
28/// # const fn int_to_node(value: u64) -> Word {
29/// # [Felt::new(value), ZERO, ZERO, ZERO]
30/// # }
31/// # let A = int_to_node(1);
32/// # let B = int_to_node(2);
33/// # let C = int_to_node(3);
34/// # let D = int_to_node(4);
35/// # let E = int_to_node(5);
36/// # let F = int_to_node(6);
37/// # let G = int_to_node(7);
38/// # let H0 = int_to_node(8);
39/// # let H1 = int_to_node(9);
40/// # let T0 = MerkleTree::new([A, B, C, D, E, F, G, H0].to_vec()).expect("even number of leaves provided");
41/// # let T1 = MerkleTree::new([A, B, C, D, E, F, G, H1].to_vec()).expect("even number of leaves provided");
42/// # let ROOT0 = T0.root();
43/// # let ROOT1 = T1.root();
44/// let mut store = MerkleStore::new();
45///
46/// // the store is initialized with the SMT empty nodes
47/// assert_eq!(store.num_internal_nodes(), 255);
48///
49/// // populates the store with two merkle trees, common nodes are shared
50/// store.add_merkle_tree([A, B, C, D, E, F, G, H0]);
51/// store.add_merkle_tree([A, B, C, D, E, F, G, H1]);
52///
53/// // every leaf except the last are the same
54/// for i in 0..7 {
55/// let d0 = store.get_node(ROOT0, NodeIndex::new(3, i)).unwrap();
56/// let d1 = store.get_node(ROOT1, NodeIndex::new(3, i)).unwrap();
57/// assert_eq!(d0, d1, "Both trees have the same leaf at pos {i}");
58/// }
59///
60/// // The leafs A-B-C-D are the same for both trees, so are their 2 immediate parents
61/// for i in 0..4 {
62/// let d0 = store.get_path(ROOT0, NodeIndex::new(3, i)).unwrap();
63/// let d1 = store.get_path(ROOT1, NodeIndex::new(3, i)).unwrap();
64/// assert_eq!(d0.path[0..2], d1.path[0..2], "Both sub-trees are equal up to two levels");
65/// }
66///
67/// // Common internal nodes are shared, the two added trees have a total of 30, but the store has
68/// // only 10 new entries, corresponding to the 10 unique internal nodes of these trees.
69/// assert_eq!(store.num_internal_nodes() - 255, 10);
70/// ```
71#[derive(Debug, Clone, Eq, PartialEq)]
72pub struct MerkleStore {
73 nodes: BTreeMap<RpoDigest, Node>,
74}
75
76impl Default for MerkleStore {
77 fn default() -> Self {
78 Self::new()
79 }
80}
81
82impl MerkleStore {
83 // CONSTRUCTORS
84 // --------------------------------------------------------------------------------------------
85
86 /// Creates an empty `MerkleStore` instance.
87 pub fn new() -> MerkleStore {
88 // pre-populate the store with the empty hashes
89 let subtrees = EmptySubtreeRoots::empty_hashes(255);
90 let nodes = subtrees
91 .iter()
92 .rev()
93 .copied()
94 .zip(subtrees.iter().rev().skip(1).copied())
95 .map(|(child, parent)| {
96 (
97 parent,
98 Node {
99 left: child,
100 right: child,
101 },
102 )
103 })
104 .collect();
105
106 MerkleStore { nodes }
107 }
108
109 /// Appends the provided merkle tree represented by its `leaves` to the set.
110 pub fn with_merkle_tree<I>(mut self, leaves: I) -> Result<Self, MerkleError>
111 where
112 I: IntoIterator<Item = Word>,
113 {
114 self.add_merkle_tree(leaves)?;
115 Ok(self)
116 }
117
118 /// Appends the provided sparse merkle tree represented by its `entries` to the set.
119 pub fn with_sparse_merkle_tree<R, I>(mut self, entries: R) -> Result<Self, MerkleError>
120 where
121 R: IntoIterator<IntoIter = I>,
122 I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
123 {
124 self.add_sparse_merkle_tree(entries)?;
125 Ok(self)
126 }
127
128 /// Appends the provided merkle path set.
129 pub fn with_merkle_path(
130 mut self,
131 index_value: u64,
132 node: Word,
133 path: MerklePath,
134 ) -> Result<Self, MerkleError> {
135 self.add_merkle_path(index_value, node, path)?;
136 Ok(self)
137 }
138
139 /// Appends the provided merkle path set.
140 pub fn with_merkle_paths<I>(mut self, paths: I) -> Result<Self, MerkleError>
141 where
142 I: IntoIterator<Item = (u64, Word, MerklePath)>,
143 {
144 self.add_merkle_paths(paths)?;
145 Ok(self)
146 }
147
148 // PUBLIC ACCESSORS
149 // --------------------------------------------------------------------------------------------
150
151 /// Return a count of the non-leaf nodes in the store.
152 pub fn num_internal_nodes(&self) -> usize {
153 self.nodes.len()
154 }
155
156 /// Returns the node at `index` rooted on the tree `root`.
157 ///
158 /// # Errors
159 ///
160 /// This method can return the following errors:
161 /// - `RootNotInStore` if the `root` is not present in the store.
162 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
163 pub fn get_node(&self, root: Word, index: NodeIndex) -> Result<Word, MerkleError> {
164 let mut hash: RpoDigest = root.into();
165
166 // corner case: check the root is in the store when called with index `NodeIndex::root()`
167 self.nodes
168 .get(&hash)
169 .ok_or(MerkleError::RootNotInStore(hash.into()))?;
170
171 for bit in index.bit_iterator().rev() {
172 let node = self
173 .nodes
174 .get(&hash)
175 .ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
176 hash = if bit { node.right } else { node.left }
177 }
178
179 Ok(hash.into())
180 }
181
182 /// Returns the node at the specified `index` and its opening to the `root`.
183 ///
184 /// The path starts at the sibling of the target leaf.
185 ///
186 /// # Errors
187 ///
188 /// This method can return the following errors:
189 /// - `RootNotInStore` if the `root` is not present in the store.
190 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
191 pub fn get_path(&self, root: Word, index: NodeIndex) -> Result<ValuePath, MerkleError> {
192 let mut hash: RpoDigest = root.into();
193 let mut path = Vec::with_capacity(index.depth().into());
194
195 // corner case: check the root is in the store when called with index `NodeIndex::root()`
196 self.nodes
197 .get(&hash)
198 .ok_or(MerkleError::RootNotInStore(hash.into()))?;
199
200 for bit in index.bit_iterator().rev() {
201 let node = self
202 .nodes
203 .get(&hash)
204 .ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
205
206 hash = if bit {
207 path.push(node.left.into());
208 node.right
209 } else {
210 path.push(node.right.into());
211 node.left
212 }
213 }
214
215 // the path is computed from root to leaf, so it must be reversed
216 path.reverse();
217
218 Ok(ValuePath {
219 value: hash.into(),
220 path: MerklePath::new(path),
221 })
222 }
223
224 // STATE MUTATORS
225 // --------------------------------------------------------------------------------------------
226
227 /// Adds all the nodes of a Merkle tree represented by `leaves`.
228 ///
229 /// This will instantiate a Merkle tree using `leaves` and include all the nodes into the
230 /// store.
231 ///
232 /// # Errors
233 ///
234 /// This method may return the following errors:
235 /// - `DepthTooSmall` if leaves is empty or contains only 1 element
236 /// - `NumLeavesNotPowerOfTwo` if the number of leaves is not a power-of-two
237 pub fn add_merkle_tree<I>(&mut self, leaves: I) -> Result<Word, MerkleError>
238 where
239 I: IntoIterator<Item = Word>,
240 {
241 let leaves: Vec<_> = leaves.into_iter().collect();
242 if leaves.len() < 2 {
243 return Err(MerkleError::DepthTooSmall(leaves.len() as u8));
244 }
245
246 let layers = leaves.len().ilog2();
247 let tree = MerkleTree::new(leaves)?;
248
249 let mut depth = 0;
250 let mut parent_offset = 1;
251 let mut child_offset = 2;
252 while depth < layers {
253 let layer_size = 1usize << depth;
254 for _ in 0..layer_size {
255 // merkle tree is using level form representation, so left and right siblings are
256 // next to each other
257 let left = tree.nodes[child_offset];
258 let right = tree.nodes[child_offset + 1];
259 self.nodes.insert(
260 tree.nodes[parent_offset].into(),
261 Node {
262 left: left.into(),
263 right: right.into(),
264 },
265 );
266 parent_offset += 1;
267 child_offset += 2;
268 }
269 depth += 1;
270 }
271
272 Ok(tree.nodes[1])
273 }
274
275 /// Adds all the nodes of a Sparse Merkle tree represented by `entries`.
276 ///
277 /// This will instantiate a Sparse Merkle tree using `entries` and include all the nodes into
278 /// the store.
279 ///
280 /// # Errors
281 ///
282 /// This will return `InvalidEntriesCount` if the length of `entries` is not `63`.
283 pub fn add_sparse_merkle_tree<R, I>(&mut self, entries: R) -> Result<Word, MerkleError>
284 where
285 R: IntoIterator<IntoIter = I>,
286 I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
287 {
288 let smt = SimpleSmt::new(SimpleSmt::MAX_DEPTH)?.with_leaves(entries)?;
289 for branch in smt.store.branches.values() {
290 let parent = Rpo256::merge(&[branch.left, branch.right]);
291 self.nodes.insert(
292 parent,
293 Node {
294 left: branch.left,
295 right: branch.right,
296 },
297 );
298 }
299
300 Ok(smt.root())
301 }
302
303 /// Adds all the nodes of a Merkle path represented by `path`, opening to `node`. Returns the
304 /// new root.
305 ///
306 /// This will compute the sibling elements determined by the Merkle `path` and `node`, and
307 /// include all the nodes into the store.
308 pub fn add_merkle_path(
309 &mut self,
310 index_value: u64,
311 mut node: Word,
312 path: MerklePath,
313 ) -> Result<Word, MerkleError> {
314 let mut index = NodeIndex::new(self.nodes.len() as u8, index_value);
315
316 for sibling in path {
317 let (left, right) = match index.is_value_odd() {
318 true => (sibling, node),
319 false => (node, sibling),
320 };
321 let parent = Rpo256::merge(&[left.into(), right.into()]);
322 self.nodes.insert(
323 parent,
324 Node {
325 left: left.into(),
326 right: right.into(),
327 },
328 );
329
330 index.move_up();
331 node = parent.into();
332 }
333
334 Ok(node)
335 }
336
337 /// Adds all the nodes of multiple Merkle paths into the store.
338 ///
339 /// This will compute the sibling elements for each Merkle `path` and include all the nodes
340 /// into the store.
341 ///
342 /// For further reference, check [MerkleStore::add_merkle_path].
343 ///
344 /// # Errors
345 ///
346 /// Every path must resolve to the same root, otherwise this will return an `ConflictingRoots`
347 /// error.
348 pub fn add_merkle_paths<I>(&mut self, paths: I) -> Result<Word, MerkleError>
349 where
350 I: IntoIterator<Item = (u64, Word, MerklePath)>,
351 {
352 let paths: Vec<(u64, Word, MerklePath)> = paths.into_iter().collect();
353
354 let roots: BTreeSet<RpoDigest> = paths
355 .iter()
356 .map(|(index, node, path)| path.compute_root(*index, *node).into())
357 .collect();
358
359 if roots.len() != 1 {
360 return Err(MerkleError::ConflictingRoots(
361 roots.iter().map(|v| Word::from(*v)).collect(),
362 ));
363 }
364
365 for (index_value, node, path) in paths {
366 self.add_merkle_path(index_value, node, path)?;
367 }
368
369 Ok(roots.iter().next().unwrap().into())
370 }
371
372 /// Appends the provided [MerklePathSet] into the store.
373 ///
374 /// For further reference, check [MerkleStore::add_merkle_path].
375 pub fn add_merkle_path_set(&mut self, path_set: &MerklePathSet) -> Result<Word, MerkleError> {
376 let root = path_set.root();
377 for (index, path) in path_set.to_paths() {
378 self.add_merkle_path(index, path.value, path.path)?;
379 }
380 Ok(root)
381 }
382
383 /// Sets a node to `value`.
384 ///
385 /// # Errors
386 ///
387 /// This method can return the following errors:
388 /// - `RootNotInStore` if the `root` is not present in the store.
389 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
390 pub fn set_node(
391 &mut self,
392 mut root: Word,
393 index: NodeIndex,
394 value: Word,
395 ) -> Result<RootPath, MerkleError> {
396 let node = value;
397 let ValuePath { value, path } = self.get_path(root, index)?;
398
399 // performs the update only if the node value differs from the opening
400 if node != value {
401 root = self.add_merkle_path(index.value(), node, path.clone())?;
402 }
403
404 Ok(RootPath { root, path })
405 }
406
407 pub fn merge_roots(&mut self, root1: Word, root2: Word) -> Result<Word, MerkleError> {
408 let root1: RpoDigest = root1.into();
409 let root2: RpoDigest = root2.into();
410
411 if !self.nodes.contains_key(&root1) {
412 Err(MerkleError::NodeNotInStore(
413 root1.into(),
414 NodeIndex::new(0, 0),
415 ))
416 } else if !self.nodes.contains_key(&root1) {
417 Err(MerkleError::NodeNotInStore(
418 root2.into(),
419 NodeIndex::new(0, 0),
420 ))
421 } else {
422 let parent: Word = Rpo256::merge(&[root1, root2]).into();
423 self.nodes.insert(
424 parent.into(),
425 Node {
426 left: root1,
427 right: root2,
428 },
429 );
430
431 Ok(parent)
432 }
433 }
434}
435
436// SERIALIZATION
437// ================================================================================================
438
439impl Serializable for Node {
440 fn write_into<W: ByteWriter>(&self, target: &mut W) {
441 self.left.write_into(target);
442 self.right.write_into(target);
443 }
444}
445
446impl Deserializable for Node {
447 fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
448 let left = RpoDigest::read_from(source)?;
449 let right = RpoDigest::read_from(source)?;
450 Ok(Node { left, right })
451 }
452}
453
454impl Serializable for MerkleStore {
455 fn write_into<W: ByteWriter>(&self, target: &mut W) {
456 target.write_u64(self.nodes.len() as u64);
457
458 for (k, v) in self.nodes.iter() {
459 k.write_into(target);
460 v.write_into(target);
461 }
462 }
463}
464
465impl Deserializable for MerkleStore {
466 fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
467 let len = source.read_u64()?;
468 let mut nodes: BTreeMap<RpoDigest, Node> = BTreeMap::new();
469
470 for _ in 0..len {
471 let key = RpoDigest::read_from(source)?;
472 let value = Node::read_from(source)?;
473 nodes.insert(key, value);
474 }
475
476 Ok(MerkleStore { nodes })
477 }
478}