feat: Implement email and transaction body commitment functions with Poseidon hash; update Cargo.toml dependencies and add new commit module.

packages/rust-verifier/Cargo.toml

@@ -11,7 +11,10 @@ ark-ff = { version = "=0.4.1", default-features = false, features = ["parallel",
 ark-bn254 = { version = "=0.4.0" }
 ark-groth16 = { version = "=0.4.0", default-features = false, features = ["parallel"] }
 ark-serialize = { version = "=0.4.1", default-features = false }
+poseidon-ark = {git = "https://github.com/arnaucube/poseidon-ark"}
+
 
 serde_json = "=1.0.94"
 serde = "*"
 clap = { version = "4.0", features = ["derive"] }
+base64 = "0.22.1"

packages/rust-verifier/src/commit.rs

@@ -0,0 +1,93 @@
+use crate::verifier_utils::GrothFp;
+use ark_ff::*;
+use poseidon_ark as poseidon;
+
+const EMAIL_MAX_BYTES: usize = 256;
+const TX_BODY_MAX_BYTES: usize = 512;
+
+pub fn calculate_email_commitment(salt: &str, email: &str) -> GrothFp {
+    let padded_salt_bytes = pad_bytes(salt.as_bytes(), 31);
+    let padded_email_bytes = pad_bytes(email.as_bytes(), EMAIL_MAX_BYTES);
+    let mut salt = pack_bytes_into_fields(padded_salt_bytes);
+    let email = pack_bytes_into_fields(padded_email_bytes);
+    salt.extend(email);
+    let poseidon = poseidon::Poseidon::new();
+    poseidon.hash(salt).unwrap()
+}
+
+pub fn calculate_tx_body_commitment(tx: &str) -> GrothFp {
+    let padded_tx_bytes = pad_bytes(tx.as_bytes(), TX_BODY_MAX_BYTES);
+    let tx = pack_bytes_into_fields(padded_tx_bytes);
+    let poseidon = poseidon::Poseidon::new();
+    let mut commitment = GrothFp::zero(); // Initialize commitment with an initial value
+
+    tx.chunks(16).enumerate().for_each(|(i, chunk)| {
+        let chunk_commitment = poseidon.hash(chunk.to_vec()).unwrap();
+        commitment = if i == 0 {
+            chunk_commitment
+        } else {
+            poseidon.hash(vec![commitment, chunk_commitment]).unwrap()
+        };
+    });
+
+    commitment
+}
+
+fn pack_bytes_into_fields(bytes: Vec<u8>) -> Vec<GrothFp> {
+    // convert each 31 bytes into one field element
+    let mut fields = vec![];
+    bytes.chunks(31).for_each(|chunk| {
+        fields.push(GrothFp::from_le_bytes_mod_order(chunk));
+    });
+    fields
+}
+
+fn pad_bytes(bytes: &[u8], length: usize) -> Vec<u8> {
+    let mut padded = bytes.to_vec();
+    let padding = length - bytes.len();
+    for _ in 0..padding {
+        padded.push(0);
+    }
+    padded
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::str::FromStr;
+
+    #[test]
+    fn should_calculate_email_commitment() {
+        let salt_str = "XRhMS5Nc2dTZW5kEpAB";
+        let email_str = "thezdev1@gmail.com";
+
+        let commitment = calculate_email_commitment(&salt_str, &email_str);
+
+        assert_eq!(
+            commitment,
+            Fp::from_str(
+                "20222897760242655042591071331570003228637614099423116142933693104079157558229"
+            )
+            .unwrap()
+        );
+    }
+
+    #[test]
+    fn should_calculate_tx_body_commitment() {
+        let tx_body = "CrQBCrEBChwvY29zbW9zLmJhbmsudjFiZXRhMS5Nc2dTZW5kEpABCj94aW9uMWd2cDl5djZndDBwcmdzc3\
+        ZueWNudXpnZWszZmtyeGxsZnhxaG0wNzYwMmt4Zmc4dXI2NHNuMnAycDkSP3hpb24xNGNuMG40ZjM4ODJzZ3B2NWQ5ZzA2dzNxN3hzZ\
+        m51N3B1enltZDk5ZTM3ZHAwemQ4bTZscXpwemwwbRoMCgV1eGlvbhIDMTAwEmEKTQpDCh0vYWJzdHJhY3RhY2NvdW50LnYxLk5pbFB1\
+        YktleRIiCiBDAlIzSFvCNEIMmTE+CRm0U2Gb/0mBfb/aeqxkoPweqxIECgIIARh/EhAKCgoFdXhpb24SATAQwJoMGg54aW9uLXRlc3R\
+        uZXQtMSCLjAo=";
+
+        let commitment = calculate_tx_body_commitment(&tx_body);
+
+        assert_eq!(
+            commitment,
+            Fp::from_str(
+                "21532090391056315603450239923154193952164369422267200983793686866358632420524"
+            )
+            .unwrap()
+        );
+    }
+}

packages/rust-verifier/src/lib.rs

@@ -1,2 +1,3 @@
+pub mod commit;
 pub mod sample_verifier;
 pub mod verifier_utils;