Implemented and Tested Starkware Poseidon

Cargo.toml

@@ -1,9 +1,8 @@
-[package]
-name = "pumice"
-version = "0.1.0"
-edition = "2021"
+[workspace]
+members = ["felt", "merkle", "poseidon"]
+resolver = "2"
 
-[dependencies]
+[workspace.dependencies]
 anyhow = "1.0.86"
 ark-ff = "0.4.2"
 ark-poly = "0.4.2"

felt/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "felt"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+ark-ff.workspace = true

src/felt252.rs → felt/src/lib.rs

@@ -1,3 +1,5 @@
+use ark_ff::Zero;
+
 pub use container::Felt252;
 
 #[allow(non_local_definitions)]
@@ -16,6 +18,24 @@ mod container {
     pub type Felt252 = Fp256<MontBackend<Felt252Config, 4>>;
 }
 
+/// This method is used for testing / debugging purposes.
+/// It provides a convenient way to create a `Felt252` from a hex string.
+///
+/// Warning: this method is slow and will panic if the input is not a valid hex string.
+pub fn hex(hex: &str) -> Felt252 {
+    let mut chars = hex.chars();
+    assert!(chars.next().unwrap() == '0');
+    assert!(chars.next().unwrap() == 'x');
+
+    let mut res = Felt252::zero();
+    for digit in chars {
+        let val = u8::from_str_radix(&digit.to_string(), 0x10).unwrap();
+        res *= Felt252::from(0x10u64);
+        res += Felt252::from(val as u64);
+    }
+    res
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

merkle/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "merkle"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+ark-ff.workspace = true

src/merkle/mod.rs → merkle/src/lib.rs

@@ -47,6 +47,7 @@ impl<F: Field, H: Hasher<F>> MerkleTree<F, H> {
     ///
     /// Returns an error type for easier "monadic style" chaining.
     #[allow(dead_code)]
+    #[allow(clippy::result_unit_err)]
     pub fn verify_decommitment(
         &self,
         comm: H::Output,

poseidon/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "poseidon"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+ark-ff.workspace = true
+felt = { path = "../felt" }
+
+[dev-dependencies]
+criterion = "0.5.1"
+
+[[bench]]
+name = "poseidon"
+harness = false

poseidon/README.md

@@ -0,0 +1 @@
+# StarkWare Poseidon

poseidon/benches/poseidon.rs

@@ -0,0 +1,45 @@
+use ark_ff::BigInt;
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+
+use felt::Felt252;
+use poseidon::{FieldHasher, Poseidon3};
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let left = Felt252::new(BigInt([
+        0xdeadbeefdeadbeef,
+        0xdeadbeefdeadbeef,
+        0xdeadbeefdeadbeef,
+        0xdeadbeefdeadbeef,
+    ]));
+
+    let right = Felt252::new(BigInt([
+        0xcafebabecafebabe,
+        0xcafebabecafebabe,
+        0xcafebabecafebabe,
+        0xcafebabecafebabe,
+    ]));
+
+    let elems = [left, right].into_iter().cycle();
+    let elems_4 = elems.clone().take(4).collect::<Vec<_>>();
+    let elems_8 = elems.clone().take(8).collect::<Vec<_>>();
+    let elems_16 = elems.clone().take(16).collect::<Vec<_>>();
+
+    c.bench_function("Poseidon3::pair", |b| {
+        b.iter(|| black_box(Poseidon3::pair(left, right)))
+    });
+
+    c.bench_function("Poseidon3::hash(|4|)", |b| {
+        b.iter(|| black_box(Poseidon3::hash(&elems_4)))
+    });
+
+    c.bench_function("Poseidon3::hash(|8|)", |b| {
+        b.iter(|| black_box(Poseidon3::hash(&elems_8)))
+    });
+
+    c.bench_function("Poseidon3::hash(|16|)", |b| {
+        b.iter(|| black_box(Poseidon3::hash(&elems_16)))
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);