Handle single element cases in MerkleTree and update tests (#871)

* Handle single element cases in MerkleTree and update test * Apply rustfmt to format code * fix clippy issues * fix clippy issues * fix clippy issues * save work * save work * fix deleted coments by mistake * run cargo fmt * add test to verify Merkle tree with a single element * cargo fmt * handle single element case * run cargo fmt * suggested changes * save work * change function name to better describe its actual operation
lambdaclass · Jun 12, 2024 · e465d7c · e465d7c
1 parent f6dda1c
commit e465d7c
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Showing 8 changed files with 87 additions and 25 deletions.
diff --git a/crypto/benches/criterion_merkle.rs b/crypto/benches/criterion_merkle.rs
@@ -8,9 +8,9 @@ use lambdaworks_math::{
     field::fields::fft_friendly::stark_252_prime_field::Stark252PrimeField,
 };
 use sha3::Keccak256;
+
 type F = Stark252PrimeField;
 type FE = FieldElement<F>;
-
 type TreeBackend = FieldElementBackend<F, Keccak256, 32>;
 
 fn merkle_tree_benchmarks(c: &mut Criterion) {
@@ -19,10 +19,11 @@ fn merkle_tree_benchmarks(c: &mut Criterion) {
     group.measurement_time(Duration::from_secs(30));
 
     // NOTE: the values to hash don't really matter, so let's go with the easy ones.
+
     let unhashed_leaves: Vec<_> = core::iter::successors(Some(FE::zero()), |s| Some(s + FE::one()))
-        // `(1 << 20) + 1` exploits worst cases in terms of rounding up to powers of 2.
         .take((1 << 20) + 1)
         .collect();
+    // `(1 << 20) + 1` exploits worst cases in terms of rounding up to powers of 2.
 
     group.bench_with_input(
         "build",
@@ -31,6 +32,8 @@ fn merkle_tree_benchmarks(c: &mut Criterion) {
             bench.iter_with_large_drop(|| MerkleTree::<TreeBackend>::build(unhashed_leaves));
         },
     );
+
+    group.finish();
 }
 
 criterion_group!(merkle_tree, merkle_tree_benchmarks);

diff --git a/crypto/src/hash/sha3/mod.rs b/crypto/src/hash/sha3/mod.rs
@@ -36,7 +36,7 @@ impl Sha3Hasher {
         let a = [b_0.clone(), Self::i2osp(1, 1), dst_prime.clone()].concat();
         let b_1 = Sha3_256::digest(a).to_vec();
 
-        let mut b_vals = Vec::<Vec<u8>>::with_capacity(ell as usize * b_in_bytes as usize);
+        let mut b_vals = Vec::<Vec<u8>>::with_capacity(ell as usize);
         b_vals.push(b_1);
         for idx in 1..ell {
             let aux = Self::strxor(&b_0, &b_vals[idx as usize - 1]);
@@ -57,7 +57,7 @@ impl Sha3Hasher {
             digits.push((x_aux % 256) as u8);
             x_aux /= 256;
         }
-        digits.resize(digits.len() + (length - digits.len() as u64) as usize, 0);
+        digits.resize(length as usize, 0);
         digits.reverse();
         digits
     }
@@ -66,3 +66,9 @@ impl Sha3Hasher {
         a.iter().zip(b).map(|(a, b)| a ^ b).collect()
     }
 }
+
+impl Default for Sha3Hasher {
+    fn default() -> Self {
+        Self::new()
+    }
+}
diff --git a/crypto/src/merkle_tree/merkle.rs b/crypto/src/merkle_tree/merkle.rs
@@ -8,7 +8,6 @@ use super::{proof::Proof, traits::IsMerkleTreeBackend, utils::*};
 pub enum Error {
     OutOfBounds,
 }
-
 impl Display for Error {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Accessed node was out of bound")
@@ -34,6 +33,11 @@ where
     pub fn build(unhashed_leaves: &[B::Data]) -> Self {
         let mut hashed_leaves: Vec<B::Node> = B::hash_leaves(unhashed_leaves);
 
+        // If there is only one node, handle it specially
+        if hashed_leaves.len() == 1 {
+            hashed_leaves.push(hashed_leaves[0].clone());
+        }
+
         //The leaf must be a power of 2 set
         hashed_leaves = complete_until_power_of_two(&mut hashed_leaves);
         let leaves_len = hashed_leaves.len();
@@ -82,7 +86,6 @@ where
         Ok(merkle_path)
     }
 }
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -93,12 +96,12 @@ mod tests {
     const MODULUS: u64 = 13;
     type U64PF = U64PrimeField<MODULUS>;
     type FE = FieldElement<U64PF>;
+
     #[test]
-    // expected | 10 | 3 | 7 | 1 | 2 | 3 | 4 |
     fn build_merkle_tree_from_a_power_of_two_list_of_values() {
         let values: Vec<FE> = (1..5).map(FE::new).collect();
         let merkle_tree = MerkleTree::<TestBackend<U64PF>>::build(&values);
-        assert_eq!(merkle_tree.root, FE::new(20));
+        assert_eq!(merkle_tree.root, FE::new(7)); // Adjusted expected value
     }
 
     #[test]
@@ -110,6 +113,17 @@ mod tests {
 
         let values: Vec<FE> = (1..6).map(FE::new).collect();
         let merkle_tree = MerkleTree::<TestBackend<U64PF>>::build(&values);
-        assert_eq!(merkle_tree.root, FE::new(8));
+        assert_eq!(merkle_tree.root, FE::new(8)); // Adjusted expected value
+    }
+
+    #[test]
+    fn build_merkle_tree_from_a_single_value() {
+        const MODULUS: u64 = 13;
+        type U64PF = U64PrimeField<MODULUS>;
+        type FE = FieldElement<U64PF>;
+
+        let values: Vec<FE> = vec![FE::new(1)]; // Single element
+        let merkle_tree = MerkleTree::<TestBackend<U64PF>>::build(&values);
+        assert_eq!(merkle_tree.root, FE::new(4)); // Adjusted expected value
     }
 }
diff --git a/crypto/src/merkle_tree/proof.rs b/crypto/src/merkle_tree/proof.rs
@@ -152,4 +152,29 @@ mod tests {
             assert_eq!(node, expected_node);
         }
     }
+
+    #[test]
+    fn verify_merkle_proof_for_single_value() {
+        const MODULUS: u64 = 13;
+        type U64PF = U64PrimeField<MODULUS>;
+        type FE = FieldElement<U64PF>;
+
+        let values: Vec<FE> = vec![FE::new(1)]; // Single element
+        let merkle_tree = MerkleTree::<TestBackend<U64PF>>::build(&values);
+
+        // Update the expected root value based on the actual logic of TestBackend
+        // For example, if combining two `1`s results in `4`, update this accordingly
+        let expected_root = FE::new(4); // Assuming combining two `1`s results in `4`
+        assert_eq!(
+            merkle_tree.root, expected_root,
+            "The root of the Merkle tree does not match the expected value."
+        );
+
+        // Verify the proof for the single element
+        let proof = merkle_tree.get_proof_by_pos(0).unwrap();
+        assert!(
+            proof.verify::<TestBackend<U64PF>>(&merkle_tree.root, 0, &values[0]),
+            "The proof verification failed for the element at position 0."
+        );
+    }
 }
diff --git a/crypto/src/merkle_tree/utils.rs b/crypto/src/merkle_tree/utils.rs
@@ -22,8 +22,11 @@ pub fn parent_index(node_index: usize) -> usize {
 
 // The list of values is completed repeating the last value to a power of two length
 pub fn complete_until_power_of_two<T: Clone>(values: &mut Vec<T>) -> Vec<T> {
+    if values.len() == 1 {
+        return values.clone(); // Return immediately if there is only one element.
+    }
     while !is_power_of_two(values.len()) {
-        values.push(values[values.len() - 1].clone())
+        values.push(values[values.len() - 1].clone());
     }
     values.to_vec()
 }

diff --git a/provers/groth16/circom-adapter/src/lib.rs b/provers/groth16/circom-adapter/src/lib.rs
@@ -79,23 +79,34 @@ fn adjust_lro_and_witness(
     let num_of_inputs = num_of_pub_inputs + num_of_private_inputs;
     let num_of_outputs = circom_r1cs["nOutputs"].as_u64().unwrap() as usize;
 
-    let mut temp;
+    let mut temp_l = Vec::with_capacity(num_of_inputs);
+    let mut temp_r = Vec::with_capacity(num_of_inputs);
+    let mut temp_o = Vec::with_capacity(num_of_inputs);
+    let mut temp_witness = Vec::with_capacity(num_of_inputs);
+
+    for i in 0..num_of_inputs {
+        temp_l.push(l[num_of_outputs + 1 + i].clone());
+        temp_r.push(r[num_of_outputs + 1 + i].clone());
+        temp_o.push(o[num_of_outputs + 1 + i].clone());
+        temp_witness.push(witness[num_of_outputs + 1 + i].clone());
+    }
+
     for i in 0..num_of_inputs {
-        temp = l[1 + i].clone();
-        l[1 + i] = l[num_of_outputs + 1 + i].clone();
-        l[num_of_outputs + 1 + i] = temp;
+        let temp_l_i = l[1 + i].clone();
+        l[1 + i].clone_from(&temp_l[i]);
+        l[num_of_outputs + 1 + i].clone_from(&temp_l_i);
 
-        temp = r[1 + i].clone();
-        r[1 + i] = r[num_of_outputs + 1 + i].clone();
-        r[num_of_outputs + 1 + i] = temp;
+        let temp_r_i = r[1 + i].clone();
+        r[1 + i].clone_from(&temp_r[i]);
+        r[num_of_outputs + 1 + i].clone_from(&temp_r_i);
 
-        temp = o[1 + i].clone();
-        o[1 + i] = o[num_of_outputs + 1 + i].clone();
-        o[num_of_outputs + 1 + i] = temp;
+        let temp_o_i = o[1 + i].clone();
+        o[1 + i].clone_from(&temp_o[i]);
+        o[num_of_outputs + 1 + i].clone_from(&temp_o_i);
 
-        let temp = witness[1 + i].clone();
-        witness[1 + i] = witness[num_of_outputs + 1 + i].clone();
-        witness[num_of_outputs + 1 + i] = temp;
+        let temp_witness_i = witness[1 + i].clone();
+        witness[1 + i].clone_from(&temp_witness[i]);
+        witness[num_of_outputs + 1 + i].clone_from(&temp_witness_i);
     }
 }
 

diff --git a/provers/stark/src/traits.rs b/provers/stark/src/traits.rs
@@ -179,7 +179,7 @@ pub trait AIR {
                 .or_insert_with(|| c.zerofier_evaluations_on_extended_domain(domain));
 
             let zerofier_evaluations = zerofier_groups.get(&zerofier_group_key).unwrap();
-            evals[c.constraint_idx()] = zerofier_evaluations.clone();
+            evals[c.constraint_idx()].clone_from(zerofier_evaluations);
         });
 
         evals

diff --git a/provers/winterfell_adapter/src/field_element/element.rs b/provers/winterfell_adapter/src/field_element/element.rs
@@ -245,7 +245,7 @@ impl Neg for AdapterFieldElement {
 
 impl PartialEq<AdapterFieldElement> for AdapterFieldElement {
     fn eq(&self, other: &AdapterFieldElement) -> bool {
-        self.0.eq(&other.0)
+        self.0 == other.0
     }
 }