# Light Protocol SDK Macros
A collection of procedural macros for the Light Protocol SDK.
## LightHasher
The `LightHasher` derive macro implements cryptographic hashing for struct types,
providing implementations of the `ToByteArray` and `DataHasher` traits.
### Attributes
- `#[hash]`: Truncates field data to BN254 field size (for large types)
- `#[skip]`: Ignores field during hashing
### Example
```rust
#[derive(LightHasher, Clone)]
pub struct MyNestedStruct {
pub a: i32,
pub b: u32,
#[hash]
pub c: String,
}
#[derive(LightHasher, Clone)]
pub struct MyAccount {
pub a: bool,
pub b: u64,
pub c: MyNestedStruct,
#[hash]
pub d: [u8; 32],
pub f: Option<usize>,
}
```
### Debug
```bash
RUST_BACKTRACE=1 cargo test
```
Prints DataHasher::hash() inputs.
## Testing
This crate includes a comprehensive test suite:
```bash
# Run all tests
cargo test
# Run fuzzing tests
cargo test --test hasher_fuzz
cargo test --test fuzz_runner
```
## Fuzzing
For deep, comprehensive fuzzing with cargo-fuzz:
```bash
# Install cargo-fuzz (requires nightly Rust)
cargo install cargo-fuzz
# Run the structure generator fuzzer (tests runtime behavior)
cargo +nightly fuzz run struct_generation -- -max_total_time=300
# Run the macro input fuzzer (tests parsing various struct definitions)
cargo +nightly fuzz run macro_input -- -max_total_time=300
```
For more details, see the [fuzzing documentation](fuzz/README.md).