introduce PackedProofs to semaphore-rs

Cargo.toml

@@ -87,6 +87,7 @@ bincode = "1.3.3"
 # TODO: Remove
 ethers-core = { git = "https://github.com/gakonst/ethers-rs", default-features = false }
 bytemuck = "1.13.1"
+ethabi = "18.0.0"
 
 [dev-dependencies]
 serial_test = "3"

src/lib.rs

@@ -11,6 +11,7 @@ pub mod hash;
 pub mod identity;
 pub mod lazy_merkle_tree;
 pub mod merkle_tree;
+pub mod packed_proof;
 pub mod poseidon;
 pub mod poseidon_tree;
 pub mod protocol;

src/packed_proof.rs

@@ -0,0 +1,112 @@
+use std::{
+    fmt::Display,
+    str::{from_utf8, FromStr},
+};
+
+use crate::protocol::Proof;
+use ethabi::{decode, encode, ParamType, Token};
+use ethers_core::types::U256;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+use crate::util::{bytes_from_hex, bytes_to_hex, deserialize_bytes, serialize_bytes};
+
+/// A packed proof is a representation of the ZKP in a single attribute (as opposed to array of arrays) which is easier to transport
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct PackedProof(pub [u8; 256]);
+
+impl From<Proof> for PackedProof {
+    fn from(proof: Proof) -> Self {
+        let tokens = Token::FixedArray(vec![
+            Token::Uint(proof.0 .0),
+            Token::Uint(proof.0 .1),
+            Token::Uint(proof.1 .0[0]),
+            Token::Uint(proof.1 .0[1]),
+            Token::Uint(proof.1 .1[0]),
+            Token::Uint(proof.1 .1[1]),
+            Token::Uint(proof.2 .0),
+            Token::Uint(proof.2 .1),
+        ]);
+
+        let bytes = encode(&[tokens]);
+        let mut encoded = [0u8; 256];
+        encoded.copy_from_slice(&bytes[..256]);
+        Self(encoded)
+    }
+}
+
+impl From<PackedProof> for Proof {
+    fn from(proof: PackedProof) -> Self {
+        let decoded = decode(&vec![ParamType::Uint(256); 8], &proof.0).unwrap();
+        let decoded_uint_array = decoded
+            .into_iter()
+            .map(|x| x.into_uint().unwrap())
+            .collect::<Vec<U256>>();
+
+        let a = (decoded_uint_array[0], decoded_uint_array[1]);
+        let b = (
+            [decoded_uint_array[2], decoded_uint_array[3]],
+            [decoded_uint_array[4], decoded_uint_array[5]],
+        );
+        let c = (decoded_uint_array[6], decoded_uint_array[7]);
+        Self(a, b, c)
+    }
+}
+
+impl Display for PackedProof {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let hex = bytes_to_hex::<256, 514>(&self.0);
+        write!(
+            f,
+            "{}",
+            from_utf8(&hex).expect("failed to convert to string")
+        )
+    }
+}
+
+impl FromStr for PackedProof {
+    type Err = hex::FromHexError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        bytes_from_hex::<256>(s).map(Self)
+    }
+}
+
+impl Serialize for PackedProof {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        serialize_bytes::<256, 514, S>(serializer, &self.0)
+    }
+}
+
+impl<'de> Deserialize<'de> for PackedProof {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        let bytes = deserialize_bytes::<256, _>(deserializer)?;
+        Ok(Self(bytes))
+    }
+}
+
+#[cfg(test)]
+pub mod test {
+    use super::*;
+
+    #[test]
+    fn test_serializing_proof_into_packed_proof() {
+        let proof = Proof(
+            (U256::from(1), U256::from(2)),
+            (
+                [U256::from(3), U256::from(4)],
+                [U256::from(5), U256::from(6)],
+            ),
+            (U256::from(7), U256::from(8)),
+        );
+
+        let packed_proof = PackedProof::from(proof);
+
+        assert_eq!(packed_proof.to_string(), "0x00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000300000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000005000000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000070000000000000000000000000000000000000000000000000000000000000008");
+
+        dbg!(packed_proof.to_string());
+
+        let proof2 = Proof::from(packed_proof);
+
+        assert_eq!(proof, proof2);
+    }
+}