Added serde feature

.github/workflows/dusk_ci.yml

@@ -19,7 +19,7 @@ jobs:
     name: Nightly tests std
     uses: dusk-network/.github/.github/workflows/run-tests.yml@main
     with:
-      test_flags: --features=zeroize
+      test_flags: --features=zeroize,serde
 
   test_nightly_no_std:
     name: Nightly tests no_std

Cargo.toml

@@ -66,6 +66,18 @@ default-features = false
 version = "1"
 optional = true
 default-features = false
+
+[dependencies.serde]
+version = "1.0"
+optional = true
+
+[dependencies.serde_json]
+version = "1.0"
+optional = true
+
+[dependencies.hex]
+version = "0.4"
+optional = true
 # End Dusk dependendencies
 
 [dev-dependencies]
@@ -86,6 +98,7 @@ default = ["alloc", "bits"]
 alloc = ["ff/alloc", "group/alloc"]
 bits = ["ff/bits"]
 rkyv-impl = ["bytecheck", "dusk-bls12_381/rkyv-impl", "rkyv"]
+serde = ["dep:serde", "serde_json", "hex"]
 
 [[bench]]
 name = "fq_bench"

src/dusk.rs

@@ -7,6 +7,9 @@
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
+#[cfg(feature = "serde")]
+mod serde_support;
+
 use core::ops::Mul;
 use ff::Field;
 use subtle::{Choice, ConditionallySelectable, ConstantTimeEq, CtOption};

src/dusk/serde_support.rs

@@ -0,0 +1,115 @@
+extern crate alloc;
+
+use alloc::string::String;
+
+use serde::{de::Error, Deserialize, Deserializer, Serialize, Serializer};
+
+use crate::{AffinePoint, ExtendedPoint};
+
+impl Serialize for AffinePoint {
+    fn serialize<S: Serializer>(
+        &self,
+        serializer: S,
+    ) -> Result<S::Ok, S::Error> {
+        let s = hex::encode(self.to_bytes());
+        serializer.serialize_str(&s)
+    }
+}
+
+impl<'de> Deserialize<'de> for AffinePoint {
+    fn deserialize<D: Deserializer<'de>>(
+        deserializer: D,
+    ) -> Result<Self, D::Error> {
+        let s = String::deserialize(deserializer)?;
+        let decoded = hex::decode(&s).map_err(Error::custom)?;
+        let decoded_len = decoded.len();
+        let bytes: [u8; 32] = decoded
+            .try_into()
+            .map_err(|_| Error::invalid_length(decoded_len, &"32"))?;
+        AffinePoint::from_bytes(bytes)
+            .into_option()
+            .ok_or(Error::custom(
+                "Failed to deserialize AffinePoint: invalid AffinePoint",
+            ))
+    }
+}
+
+impl Serialize for ExtendedPoint {
+    fn serialize<S: Serializer>(
+        &self,
+        serializer: S,
+    ) -> Result<S::Ok, S::Error> {
+        AffinePoint::from(self).serialize(serializer)
+    }
+}
+
+impl<'de> Deserialize<'de> for ExtendedPoint {
+    fn deserialize<D: Deserializer<'de>>(
+        deserializer: D,
+    ) -> Result<Self, D::Error> {
+        AffinePoint::deserialize(deserializer).map(Into::into)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use group::Group;
+
+    use crate::{AffinePoint, ExtendedPoint};
+
+    #[test]
+    fn affine_point() {
+        let point = AffinePoint::identity();
+        let ser = serde_json::to_string(&point).unwrap();
+        let deser = serde_json::from_str(&ser).unwrap();
+        assert_eq!(point, deser);
+    }
+
+    #[test]
+    fn extended_point() {
+        let mut rng = rand_core::OsRng;
+        let point = ExtendedPoint::random(&mut rng);
+        let ser = serde_json::to_string(&point).unwrap();
+        let deser = serde_json::from_str(&ser).unwrap();
+        assert_eq!(point, deser);
+    }
+
+    #[test]
+    fn wrong_encoded() {
+        let wrong_encoded = "wrong-encoded";
+
+        let affine_point: Result<AffinePoint, _> =
+            serde_json::from_str(&wrong_encoded);
+        assert!(affine_point.is_err());
+
+        let extended_point: Result<ExtendedPoint, _> =
+            serde_json::from_str(&wrong_encoded);
+        assert!(extended_point.is_err());
+    }
+
+    #[test]
+    fn too_long_encoded() {
+        let length_33_enc = "\"e4ab9de40283a85d6ea0cd0120500697d8b01c71b7b4b520292252d20937000631\"";
+
+        let affine_point: Result<AffinePoint, _> =
+            serde_json::from_str(&length_33_enc);
+        assert!(affine_point.is_err());
+
+        let extended_point: Result<ExtendedPoint, _> =
+            serde_json::from_str(&length_33_enc);
+        assert!(extended_point.is_err());
+    }
+
+    #[test]
+    fn too_short_encoded() {
+        let length_31_enc = "\"1751c37a1dca7aa4c048fcc6177194243edc3637bae042e167e4285945e046\"";
+
+        let affine_point: Result<AffinePoint, _> =
+            serde_json::from_str(&length_31_enc);
+        assert!(affine_point.is_err());
+
+        let extended_point: Result<ExtendedPoint, _> =
+            serde_json::from_str(&length_31_enc);
+        assert!(extended_point.is_err());
+    }
+}

src/fr/dusk.rs

@@ -275,6 +275,44 @@ impl Serializable<32> for Fr {
     }
 }
 
+#[cfg(feature = "serde")]
+mod serde_support {
+    extern crate alloc;
+
+    use alloc::string::String;
+
+    use serde::de::Error;
+    use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+    use super::Fr;
+
+    impl Serialize for Fr {
+        fn serialize<S: Serializer>(
+            &self,
+            serializer: S,
+        ) -> Result<S::Ok, S::Error> {
+            let s = hex::encode(self.to_bytes());
+            serializer.serialize_str(&s)
+        }
+    }
+
+    impl<'de> Deserialize<'de> for Fr {
+        fn deserialize<D: Deserializer<'de>>(
+            deserializer: D,
+        ) -> Result<Self, D::Error> {
+            let s = String::deserialize(deserializer)?;
+            let decoded = hex::decode(s).map_err(Error::custom)?;
+            let decoded_len = decoded.len();
+            let bytes: [u8; 32] = decoded
+                .try_into()
+                .map_err(|_| Error::invalid_length(decoded_len, &"32"))?;
+            Fr::from_bytes(&bytes)
+                .into_option()
+                .ok_or(Error::custom("Failed to deserialize Fr: invalid Fr"))
+        }
+    }
+}
+
 #[test]
 fn w_naf_3() {
     let scalar = Fr::from(1122334455u64);
@@ -366,3 +404,31 @@ fn test_zeroize() {
     scalar.zeroize();
     assert_eq!(scalar, Fr::zero());
 }
+
+#[cfg(feature = "serde")]
+#[test]
+fn serde_fr() {
+    use ff::Field;
+
+    let mut rng = rand_core::OsRng;
+    let fr = Fr::random(&mut rng);
+    let ser = serde_json::to_string(&fr).unwrap();
+    let deser = serde_json::from_str(&ser).unwrap();
+    assert_eq!(fr, deser);
+
+    // Should error when the encoding is wrong
+    let wrong_encoded = "wrong-encoded";
+    let fr: Result<Fr, _> = serde_json::from_str(&wrong_encoded);
+    assert!(fr.is_err());
+
+    // Should error when the input is too long
+    let length_33_enc = "\"e4ab9de40283a85d6ea0cd0120500697d8b01c71b7b4b520292252d20937000631\"";
+    let fr: Result<Fr, _> = serde_json::from_str(&length_33_enc);
+    assert!(fr.is_err());
+
+    // Should error when the input is too short
+    let length_31_enc =
+        "\"1751c37a1dca7aa4c048fcc6177194243edc3637bae042e167e4285945e046\"";
+    let fr: Result<Fr, _> = serde_json::from_str(&length_31_enc);
+    assert!(fr.is_err());
+}