From c40b8972fbff3813ca8ac58a9141b3ffc7c24fc4 Mon Sep 17 00:00:00 2001
From: Demilade Sonuga <demilade@dusk.network>
Date: Fri, 6 Dec 2024 13:47:33 +0100
Subject: [PATCH] Added serde feature

---
 .github/workflows/dusk_ci.yml |   6 ++
 Cargo.toml                    |  13 ++++
 src/dusk.rs                   |   3 +
 src/dusk/serde_support.rs     | 116 ++++++++++++++++++++++++++++++++++
 4 files changed, 138 insertions(+)
 create mode 100644 src/dusk/serde_support.rs

diff --git a/.github/workflows/dusk_ci.yml b/.github/workflows/dusk_ci.yml
index 86b5b79..e65f3b8 100644
--- a/.github/workflows/dusk_ci.yml
+++ b/.github/workflows/dusk_ci.yml
@@ -26,3 +26,9 @@ jobs:
     uses: dusk-network/.github/.github/workflows/run-tests.yml@main
     with:
       test_flags: --no-default-features 
+  
+  test_serde:
+    name: Serde tests
+    uses: dusk-network/.github/.github/workflows/run-tests.yml@main
+    with:
+      test_flags: --features=serde
diff --git a/Cargo.toml b/Cargo.toml
index 4a3645e..6994758 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -68,6 +68,18 @@ optional = true
 default-features = false
 # End Dusk dependendencies
 
+[dependencies.serde]
+version = "1.0"
+optional = true
+
+[dependencies.serde_json]
+version = "1.0"
+optional = true
+
+[dependencies.hex]
+version = "0.4"
+optional = true
+
 [dev-dependencies]
 criterion = "0.3"
 csv = ">= 1.0, < 1.2" # csv 1.2 has MSRV 1.60
@@ -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", "dusk-bls12_381/serde", "hex"]
 
 [[bench]]
 name = "fq_bench"
diff --git a/src/dusk.rs b/src/dusk.rs
index f311142..84d2ead 100644
--- a/src/dusk.rs
+++ b/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};
diff --git a/src/dusk/serde_support.rs b/src/dusk/serde_support.rs
new file mode 100644
index 0000000..dbeabb5
--- /dev/null
+++ b/src/dusk/serde_support.rs
@@ -0,0 +1,116 @@
+extern crate alloc;
+
+use alloc::string::String;
+
+use serde::{de::Error, Deserialize, Deserializer, Serialize, Serializer};
+
+use crate::{AffinePoint, ExtendedPoint, Fr};
+
+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 bytes: [u8; 32] = hex::decode(s)
+            .map_err(Error::custom)?
+            .try_into()
+            .map_err(|_| {
+                Error::custom(
+                    "Failed to deserialize AffinePoint: invalid byte length",
+                )
+            })?;
+        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)
+    }
+}
+
+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 bytes: [u8; 32] = hex::decode(s)
+            .map_err(Error::custom)?
+            .try_into()
+            .map_err(|_| {
+                Error::custom("Failed to deserialize Fr: invalid byte length")
+            })?;
+        Fr::from_bytes(&bytes)
+            .into_option()
+            .ok_or(Error::custom("Failed to deserialize Fr: invalid Fr"))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ff::Field;
+    use group::Group;
+
+    use crate::{AffinePoint, ExtendedPoint, Fr};
+
+    #[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 fr() {
+        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);
+    }
+}