miden-crypto/src/merkle/store/mod.rs
src/merkle/store/mod.rsRaw
1use super::mmr::{Mmr, MmrPeaks};
2use super::{
3 BTreeMap, EmptySubtreeRoots, MerkleError, MerklePath, MerklePathSet, MerkleTree, NodeIndex,
4 RootPath, Rpo256, RpoDigest, SimpleSmt, ValuePath, Vec, Word,
5};
6use crate::utils::{ByteReader, ByteWriter, Deserializable, DeserializationError, Serializable};
7
8#[cfg(test)]
9mod tests;
10
11#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
12pub struct Node {
13 left: RpoDigest,
14 right: RpoDigest,
15}
16
17/// An in-memory data store for Merkle-lized data.
18///
19/// This is a in memory data store for Merkle trees, this store allows all the nodes of multiple
20/// trees to live as long as necessary and without duplication, this allows the implementation of
21/// space efficient persistent data structures.
22///
23/// Example usage:
24///
25/// ```rust
26/// # use miden_crypto::{ZERO, Felt, Word};
27/// # use miden_crypto::merkle::{NodeIndex, MerkleStore, MerkleTree};
28/// # use miden_crypto::hash::rpo::Rpo256;
29/// # const fn int_to_node(value: u64) -> Word {
30/// # [Felt::new(value), ZERO, ZERO, ZERO]
31/// # }
32/// # let A = int_to_node(1);
33/// # let B = int_to_node(2);
34/// # let C = int_to_node(3);
35/// # let D = int_to_node(4);
36/// # let E = int_to_node(5);
37/// # let F = int_to_node(6);
38/// # let G = int_to_node(7);
39/// # let H0 = int_to_node(8);
40/// # let H1 = int_to_node(9);
41/// # let T0 = MerkleTree::new([A, B, C, D, E, F, G, H0].to_vec()).expect("even number of leaves provided");
42/// # let T1 = MerkleTree::new([A, B, C, D, E, F, G, H1].to_vec()).expect("even number of leaves provided");
43/// # let ROOT0 = T0.root();
44/// # let ROOT1 = T1.root();
45/// let mut store = MerkleStore::new();
46///
47/// // the store is initialized with the SMT empty nodes
48/// assert_eq!(store.num_internal_nodes(), 255);
49///
50/// // populates the store with two merkle trees, common nodes are shared
51/// store.add_merkle_tree([A, B, C, D, E, F, G, H0]);
52/// store.add_merkle_tree([A, B, C, D, E, F, G, H1]);
53///
54/// // every leaf except the last are the same
55/// for i in 0..7 {
56/// let idx0 = NodeIndex::new(3, i).unwrap();
57/// let d0 = store.get_node(ROOT0, idx0).unwrap();
58/// let idx1 = NodeIndex::new(3, i).unwrap();
59/// let d1 = store.get_node(ROOT1, idx1).unwrap();
60/// assert_eq!(d0, d1, "Both trees have the same leaf at pos {i}");
61/// }
62///
63/// // The leafs A-B-C-D are the same for both trees, so are their 2 immediate parents
64/// for i in 0..4 {
65/// let idx0 = NodeIndex::new(3, i).unwrap();
66/// let d0 = store.get_path(ROOT0, idx0).unwrap();
67/// let idx1 = NodeIndex::new(3, i).unwrap();
68/// let d1 = store.get_path(ROOT1, idx1).unwrap();
69/// assert_eq!(d0.path[0..2], d1.path[0..2], "Both sub-trees are equal up to two levels");
70/// }
71///
72/// // Common internal nodes are shared, the two added trees have a total of 30, but the store has
73/// // only 10 new entries, corresponding to the 10 unique internal nodes of these trees.
74/// assert_eq!(store.num_internal_nodes() - 255, 10);
75/// ```
76#[derive(Debug, Clone, Eq, PartialEq)]
77pub struct MerkleStore {
78 nodes: BTreeMap<RpoDigest, Node>,
79}
80
81impl Default for MerkleStore {
82 fn default() -> Self {
83 Self::new()
84 }
85}
86
87impl MerkleStore {
88 // CONSTRUCTORS
89 // --------------------------------------------------------------------------------------------
90
91 /// Creates an empty `MerkleStore` instance.
92 pub fn new() -> MerkleStore {
93 // pre-populate the store with the empty hashes
94 let subtrees = EmptySubtreeRoots::empty_hashes(255);
95 let nodes = subtrees
96 .iter()
97 .rev()
98 .copied()
99 .zip(subtrees.iter().rev().skip(1).copied())
100 .map(|(child, parent)| {
101 (
102 parent,
103 Node {
104 left: child,
105 right: child,
106 },
107 )
108 })
109 .collect();
110
111 MerkleStore { nodes }
112 }
113
114 /// Appends the provided merkle tree represented by its `leaves` to the set.
115 pub fn with_merkle_tree<I>(mut self, leaves: I) -> Result<Self, MerkleError>
116 where
117 I: IntoIterator<Item = Word>,
118 {
119 self.add_merkle_tree(leaves)?;
120 Ok(self)
121 }
122
123 /// Appends the provided Sparse Merkle tree represented by its `entries` to the set.
124 ///
125 /// For more information, check [MerkleStore::add_sparse_merkle_tree].
126 pub fn with_sparse_merkle_tree<R, I>(
127 mut self,
128 depth: u8,
129 entries: R,
130 ) -> Result<Self, MerkleError>
131 where
132 R: IntoIterator<IntoIter = I>,
133 I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
134 {
135 self.add_sparse_merkle_tree(depth, entries)?;
136 Ok(self)
137 }
138
139 /// Appends the provided merkle path set.
140 pub fn with_merkle_path(
141 mut self,
142 index_value: u64,
143 node: Word,
144 path: MerklePath,
145 ) -> Result<Self, MerkleError> {
146 self.add_merkle_path(index_value, node, path)?;
147 Ok(self)
148 }
149
150 /// Appends the provided merkle path set.
151 pub fn with_merkle_paths<I>(mut self, paths: I) -> Result<Self, MerkleError>
152 where
153 I: IntoIterator<Item = (u64, Word, MerklePath)>,
154 {
155 self.add_merkle_paths(paths)?;
156 Ok(self)
157 }
158
159 /// Appends the provided [Mmr] represented by its `leaves` to the set.
160 pub fn with_mmr<I>(mut self, leaves: I) -> Result<Self, MerkleError>
161 where
162 I: IntoIterator<Item = Word>,
163 {
164 self.add_mmr(leaves)?;
165 Ok(self)
166 }
167
168 // PUBLIC ACCESSORS
169 // --------------------------------------------------------------------------------------------
170
171 /// Return a count of the non-leaf nodes in the store.
172 pub fn num_internal_nodes(&self) -> usize {
173 self.nodes.len()
174 }
175
176 /// Returns the node at `index` rooted on the tree `root`.
177 ///
178 /// # Errors
179 ///
180 /// This method can return the following errors:
181 /// - `RootNotInStore` if the `root` is not present in the store.
182 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
183 pub fn get_node(&self, root: Word, index: NodeIndex) -> Result<Word, MerkleError> {
184 let mut hash: RpoDigest = root.into();
185
186 // corner case: check the root is in the store when called with index `NodeIndex::root()`
187 self.nodes
188 .get(&hash)
189 .ok_or(MerkleError::RootNotInStore(hash.into()))?;
190
191 for i in (0..index.depth()).rev() {
192 let node = self
193 .nodes
194 .get(&hash)
195 .ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
196
197 let bit = (index.value() >> i) & 1;
198 hash = if bit == 0 { node.left } else { node.right }
199 }
200
201 Ok(hash.into())
202 }
203
204 /// Returns the node at the specified `index` and its opening to the `root`.
205 ///
206 /// The path starts at the sibling of the target leaf.
207 ///
208 /// # Errors
209 ///
210 /// This method can return the following errors:
211 /// - `RootNotInStore` if the `root` is not present in the store.
212 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
213 pub fn get_path(&self, root: Word, index: NodeIndex) -> Result<ValuePath, MerkleError> {
214 let mut hash: RpoDigest = root.into();
215 let mut path = Vec::with_capacity(index.depth().into());
216
217 // corner case: check the root is in the store when called with index `NodeIndex::root()`
218 self.nodes
219 .get(&hash)
220 .ok_or(MerkleError::RootNotInStore(hash.into()))?;
221
222 for i in (0..index.depth()).rev() {
223 let node = self
224 .nodes
225 .get(&hash)
226 .ok_or(MerkleError::NodeNotInStore(hash.into(), index))?;
227
228 let bit = (index.value() >> i) & 1;
229 hash = if bit == 0 {
230 path.push(node.right.into());
231 node.left
232 } else {
233 path.push(node.left.into());
234 node.right
235 }
236 }
237
238 // the path is computed from root to leaf, so it must be reversed
239 path.reverse();
240
241 Ok(ValuePath {
242 value: hash.into(),
243 path: MerklePath::new(path),
244 })
245 }
246
247 // STATE MUTATORS
248 // --------------------------------------------------------------------------------------------
249
250 /// Adds all the nodes of a Merkle tree represented by `leaves`.
251 ///
252 /// This will instantiate a Merkle tree using `leaves` and include all the nodes into the
253 /// store.
254 ///
255 /// # Errors
256 ///
257 /// This method may return the following errors:
258 /// - `DepthTooSmall` if leaves is empty or contains only 1 element
259 /// - `NumLeavesNotPowerOfTwo` if the number of leaves is not a power-of-two
260 pub fn add_merkle_tree<I>(&mut self, leaves: I) -> Result<Word, MerkleError>
261 where
262 I: IntoIterator<Item = Word>,
263 {
264 let leaves: Vec<_> = leaves.into_iter().collect();
265 if leaves.len() < 2 {
266 return Err(MerkleError::DepthTooSmall(leaves.len() as u8));
267 }
268
269 let tree = MerkleTree::new(leaves)?;
270 for node in tree.inner_nodes() {
271 self.nodes.insert(
272 node.value.into(),
273 Node {
274 left: node.left.into(),
275 right: node.right.into(),
276 },
277 );
278 }
279
280 Ok(tree.root())
281 }
282
283 /// Adds a Sparse Merkle tree defined by the specified `entries` to the store, and returns the
284 /// root of the added tree.
285 ///
286 /// The entries are expected to contain tuples of `(index, node)` describing nodes in the tree
287 /// at `depth`.
288 ///
289 /// # Errors
290 /// Returns an error if the provided `depth` is greater than [SimpleSmt::MAX_DEPTH].
291 pub fn add_sparse_merkle_tree<R, I>(
292 &mut self,
293 depth: u8,
294 entries: R,
295 ) -> Result<Word, MerkleError>
296 where
297 R: IntoIterator<IntoIter = I>,
298 I: Iterator<Item = (u64, Word)> + ExactSizeIterator,
299 {
300 let smt = SimpleSmt::new(depth)?.with_leaves(entries)?;
301 for node in smt.inner_nodes() {
302 self.nodes.insert(
303 node.value.into(),
304 Node {
305 left: node.left.into(),
306 right: node.right.into(),
307 },
308 );
309 }
310
311 Ok(smt.root())
312 }
313
314 /// Adds all the nodes of a Merkle path represented by `path`, opening to `node`. Returns the
315 /// new root.
316 ///
317 /// This will compute the sibling elements determined by the Merkle `path` and `node`, and
318 /// include all the nodes into the store.
319 pub fn add_merkle_path(
320 &mut self,
321 index_value: u64,
322 mut node: Word,
323 path: MerklePath,
324 ) -> Result<Word, MerkleError> {
325 let mut index = NodeIndex::new(path.len() as u8, index_value)?;
326
327 for sibling in path {
328 let (left, right) = match index.is_value_odd() {
329 true => (sibling, node),
330 false => (node, sibling),
331 };
332 let parent = Rpo256::merge(&[left.into(), right.into()]);
333 self.nodes.insert(
334 parent,
335 Node {
336 left: left.into(),
337 right: right.into(),
338 },
339 );
340
341 index.move_up();
342 node = parent.into();
343 }
344
345 Ok(node)
346 }
347
348 /// Adds all the nodes of multiple Merkle paths into the store.
349 ///
350 /// This will compute the sibling elements for each Merkle `path` and include all the nodes
351 /// into the store.
352 ///
353 /// For further reference, check [MerkleStore::add_merkle_path].
354 pub fn add_merkle_paths<I>(&mut self, paths: I) -> Result<(), MerkleError>
355 where
356 I: IntoIterator<Item = (u64, Word, MerklePath)>,
357 {
358 for (index_value, node, path) in paths.into_iter() {
359 self.add_merkle_path(index_value, node, path)?;
360 }
361 Ok(())
362 }
363
364 /// Appends the provided [MerklePathSet] into the store.
365 ///
366 /// For further reference, check [MerkleStore::add_merkle_path].
367 pub fn add_merkle_path_set(&mut self, path_set: &MerklePathSet) -> Result<Word, MerkleError> {
368 let root = path_set.root();
369 for (index, path) in path_set.to_paths() {
370 self.add_merkle_path(index, path.value, path.path)?;
371 }
372 Ok(root)
373 }
374
375 /// Appends the provided [Mmr] into the store.
376 pub fn add_mmr<I>(&mut self, leaves: I) -> Result<MmrPeaks, MerkleError>
377 where
378 I: IntoIterator<Item = Word>,
379 {
380 let mmr = Mmr::from(leaves);
381 for node in mmr.inner_nodes() {
382 self.nodes.insert(
383 node.value.into(),
384 Node {
385 left: node.left.into(),
386 right: node.right.into(),
387 },
388 );
389 }
390
391 Ok(mmr.accumulator())
392 }
393
394 /// Sets a node to `value`.
395 ///
396 /// # Errors
397 ///
398 /// This method can return the following errors:
399 /// - `RootNotInStore` if the `root` is not present in the store.
400 /// - `NodeNotInStore` if a node needed to traverse from `root` to `index` is not present in the store.
401 pub fn set_node(
402 &mut self,
403 mut root: Word,
404 index: NodeIndex,
405 value: Word,
406 ) -> Result<RootPath, MerkleError> {
407 let node = value;
408 let ValuePath { value, path } = self.get_path(root, index)?;
409
410 // performs the update only if the node value differs from the opening
411 if node != value {
412 root = self.add_merkle_path(index.value(), node, path.clone())?;
413 }
414
415 Ok(RootPath { root, path })
416 }
417
418 pub fn merge_roots(&mut self, root1: Word, root2: Word) -> Result<Word, MerkleError> {
419 let root1: RpoDigest = root1.into();
420 let root2: RpoDigest = root2.into();
421
422 if !self.nodes.contains_key(&root1) {
423 Err(MerkleError::NodeNotInStore(root1.into(), NodeIndex::root()))
424 } else if !self.nodes.contains_key(&root1) {
425 Err(MerkleError::NodeNotInStore(root2.into(), NodeIndex::root()))
426 } else {
427 let parent: Word = Rpo256::merge(&[root1, root2]).into();
428 self.nodes.insert(
429 parent.into(),
430 Node {
431 left: root1,
432 right: root2,
433 },
434 );
435
436 Ok(parent)
437 }
438 }
439}
440
441// SERIALIZATION
442// ================================================================================================
443
444impl Serializable for Node {
445 fn write_into<W: ByteWriter>(&self, target: &mut W) {
446 self.left.write_into(target);
447 self.right.write_into(target);
448 }
449}
450
451impl Deserializable for Node {
452 fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
453 let left = RpoDigest::read_from(source)?;
454 let right = RpoDigest::read_from(source)?;
455 Ok(Node { left, right })
456 }
457}
458
459impl Serializable for MerkleStore {
460 fn write_into<W: ByteWriter>(&self, target: &mut W) {
461 target.write_u64(self.nodes.len() as u64);
462
463 for (k, v) in self.nodes.iter() {
464 k.write_into(target);
465 v.write_into(target);
466 }
467 }
468}
469
470impl Deserializable for MerkleStore {
471 fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
472 let len = source.read_u64()?;
473 let mut nodes: BTreeMap<RpoDigest, Node> = BTreeMap::new();
474
475 for _ in 0..len {
476 let key = RpoDigest::read_from(source)?;
477 let value = Node::read_from(source)?;
478 nodes.insert(key, value);
479 }
480
481 Ok(MerkleStore { nodes })
482 }
483}