1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
use crate::{errors::MerkleTreeError, Hasher};
use utils::{
collections::{BTreeMap, Vec},
string::ToString,
ByteReader, Deserializable, DeserializationError, Serializable,
};
pub(super) const MAX_PATHS: usize = 255;
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct BatchMerkleProof<H: Hasher> {
pub(super) leaves: Vec<H::Digest>,
pub(super) nodes: Vec<Vec<H::Digest>>,
pub(super) depth: u8,
}
impl<H: Hasher> BatchMerkleProof<H> {
pub fn from_paths(paths: &[Vec<H::Digest>], indexes: &[usize]) -> BatchMerkleProof<H> {
assert!(!paths.is_empty(), "at least one path must be provided");
assert!(
paths.len() <= MAX_PATHS,
"number of paths cannot exceed {}",
MAX_PATHS
);
assert_eq!(
paths.len(),
indexes.len(),
"number of paths must equal number of indexes"
);
let depth = paths[0].len();
let mut path_map = BTreeMap::new();
for (&index, path) in indexes.iter().zip(paths.iter().cloned()) {
assert_eq!(depth, path.len(), "not all paths have the same length");
path_map.insert(index, path);
}
let indexes = path_map.keys().cloned().collect::<Vec<_>>();
let paths = path_map.values().cloned().collect::<Vec<_>>();
path_map.clear();
let mut leaves = vec![H::Digest::default(); indexes.len()];
let mut nodes: Vec<Vec<H::Digest>> = Vec::with_capacity(indexes.len());
let mut i = 0;
while i < indexes.len() {
leaves[i] = paths[i][0];
if indexes.len() > i + 1 && are_siblings(indexes[i], indexes[i + 1]) {
leaves[i + 1] = paths[i][1];
nodes.push(vec![]);
i += 1;
} else {
nodes.push(vec![paths[i][1]]);
}
path_map.insert(indexes[i] >> 1, paths[i].clone());
i += 1;
}
for d in 2..depth {
let indexes = path_map.keys().cloned().collect::<Vec<_>>();
let mut next_path_map = BTreeMap::new();
let mut i = 0;
while i < indexes.len() {
let index = indexes[i];
let path = path_map.get(&index).unwrap();
if indexes.len() > i + 1 && are_siblings(index, indexes[i + 1]) {
i += 1;
} else {
nodes[i].push(path[d]);
}
next_path_map.insert(index >> 1, path.clone());
i += 1;
}
core::mem::swap(&mut path_map, &mut next_path_map);
}
BatchMerkleProof {
leaves,
nodes,
depth: (depth - 1) as u8,
}
}
pub fn get_root(&self, indexes: &[usize]) -> Result<H::Digest, MerkleTreeError> {
if indexes.is_empty() {
return Err(MerkleTreeError::TooFewLeafIndexes);
}
if indexes.len() > MAX_PATHS {
return Err(MerkleTreeError::TooManyLeafIndexes(
MAX_PATHS,
indexes.len(),
));
}
let mut buf = [H::Digest::default(); 2];
let mut v = BTreeMap::new();
let index_map = super::map_indexes(indexes, self.depth as usize)?;
let indexes = super::normalize_indexes(indexes);
if indexes.len() != self.nodes.len() {
return Err(MerkleTreeError::InvalidProof);
}
let offset = 2usize.pow(self.depth as u32);
let mut next_indexes: Vec<usize> = Vec::new();
let mut proof_pointers: Vec<usize> = Vec::with_capacity(indexes.len());
for (i, index) in indexes.into_iter().enumerate() {
match index_map.get(&index) {
Some(&index1) => {
if self.leaves.len() <= index1 {
return Err(MerkleTreeError::InvalidProof);
}
buf[0] = self.leaves[index1];
match index_map.get(&(index + 1)) {
Some(&index2) => {
if self.leaves.len() <= index2 {
return Err(MerkleTreeError::InvalidProof);
}
buf[1] = self.leaves[index2];
proof_pointers.push(0);
}
None => {
if self.nodes[i].is_empty() {
return Err(MerkleTreeError::InvalidProof);
}
buf[1] = self.nodes[i][0];
proof_pointers.push(1);
}
}
}
None => {
if self.nodes[i].is_empty() {
return Err(MerkleTreeError::InvalidProof);
}
buf[0] = self.nodes[i][0];
match index_map.get(&(index + 1)) {
Some(&index2) => {
if self.leaves.len() <= index2 {
return Err(MerkleTreeError::InvalidProof);
}
buf[1] = self.leaves[index2];
}
None => return Err(MerkleTreeError::InvalidProof),
}
proof_pointers.push(1);
}
}
let parent = H::merge(&buf);
let parent_index = (offset + index) >> 1;
v.insert(parent_index, parent);
next_indexes.push(parent_index);
}
for _ in 1..self.depth {
let indexes = next_indexes.clone();
next_indexes.truncate(0);
let mut i = 0;
while i < indexes.len() {
let node_index = indexes[i];
let sibling_index = node_index ^ 1;
let sibling: H::Digest;
if i + 1 < indexes.len() && indexes[i + 1] == sibling_index {
sibling = match v.get(&sibling_index) {
Some(sibling) => *sibling,
None => return Err(MerkleTreeError::InvalidProof),
};
i += 1;
} else {
let pointer = proof_pointers[i];
if self.nodes[i].len() <= pointer {
return Err(MerkleTreeError::InvalidProof);
}
sibling = self.nodes[i][pointer];
proof_pointers[i] += 1;
}
let node = match v.get(&node_index) {
Some(node) => node,
None => return Err(MerkleTreeError::InvalidProof),
};
if node_index & 1 != 0 {
buf[0] = sibling;
buf[1] = *node;
} else {
buf[0] = *node;
buf[1] = sibling;
}
let parent = H::merge(&buf);
let parent_index = node_index >> 1;
v.insert(parent_index, parent);
next_indexes.push(parent_index);
i += 1;
}
}
v.remove(&1).ok_or(MerkleTreeError::InvalidProof)
}
pub fn serialize_nodes(&self) -> Vec<u8> {
let mut result = Vec::new();
assert!(self.nodes.len() <= u8::MAX as usize, "too many paths");
result.push(self.nodes.len() as u8);
for nodes in self.nodes.iter() {
assert!(nodes.len() <= u8::MAX as usize, "too many nodes");
result.push(nodes.len() as u8);
for node in nodes.iter() {
result.append(&mut node.to_bytes());
}
}
result
}
pub fn deserialize<R: ByteReader>(
node_bytes: &mut R,
leaves: Vec<H::Digest>,
depth: u8,
) -> Result<Self, DeserializationError> {
if depth == 0 {
return Err(DeserializationError::InvalidValue(
"tree depth must be greater than zero".to_string(),
));
}
if leaves.is_empty() {
return Err(DeserializationError::InvalidValue(
"at lease one leaf must be provided".to_string(),
));
}
if leaves.len() > MAX_PATHS {
return Err(DeserializationError::InvalidValue(format!(
"number of leaves cannot exceed {}, but {} were provided",
MAX_PATHS,
leaves.len()
)));
}
let num_node_vectors = node_bytes.read_u8()? as usize;
let mut nodes = Vec::with_capacity(num_node_vectors);
for _ in 0..num_node_vectors {
let num_digests = node_bytes.read_u8()? as usize;
let digests = H::Digest::read_batch_from(node_bytes, num_digests)?;
nodes.push(digests);
}
Ok(BatchMerkleProof {
leaves,
nodes,
depth,
})
}
}
fn are_siblings(left: usize, right: usize) -> bool {
left & 1 == 0 && right - 1 == left
}