Persistent Merkle Tree
Persistent Merkle Tree (optimized & sparse & fixed-size) in Rust.
## References
- https://github.com/Rate-Limiting-Nullifier/pmtree
---
## 🛠 Install
```bash
cargo add zk-kit-pmt
```
## 📜 Usage
```rust
struct MemoryDB(HashMap);
struct MyKeccak(());
#[derive(Default)]
struct MemoryDBConfig;
impl Database for MemoryDB {
type Config = MemoryDBConfig;
fn new(_db_config: MemoryDBConfig) -> PmtreeResult {
Ok(MemoryDB(HashMap::new()))
}
fn load(_db_config: MemoryDBConfig) -> PmtreeResult {
Err(PmtreeErrorKind::DatabaseError(
DatabaseErrorKind::CannotLoadDatabase,
))
}
fn get(&self, key: DBKey) -> PmtreeResult> {
Ok(self.0.get(&key).cloned())
}
fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
self.0.insert(key, value);
Ok(())
}
fn put_batch(&mut self, subtree: HashMap) -> PmtreeResult<()> {
self.0.extend(subtree);
Ok(())
}
fn close(&mut self) -> PmtreeResult<()> {
Ok(())
}
}
impl Hasher for MyKeccak {
type Fr = [u8; 32];
fn default_leaf() -> Self::Fr {
[0; 32]
}
fn serialize(value: Self::Fr) -> Value {
value.to_vec()
}
fn deserialize(value: Value) -> Self::Fr {
value.try_into().unwrap()
}
fn hash(input: &[Self::Fr]) -> Self::Fr {
let mut output = [0; 32];
let mut hasher = Keccak::v256();
for element in input {
hasher.update(element);
}
hasher.finalize(&mut output);
output
}
}
fn main() {
let mut mt = MerkleTree::::new(2, MemoryDBConfig).unwrap();
assert_eq!(mt.capacity(), 4);
assert_eq!(mt.depth(), 2);
mt.update_next(hex!(
"c1ba1812ff680ce84c1d5b4f1087eeb08147a4d510f3496b2849df3a73f5af95"
))
.unwrap();
// closes the connection to the database
mt.close().unwrap();
}
```