feat: add optional serde support

Cargo.toml

@@ -19,8 +19,12 @@ rand = "0.4"
 byteorder = "1"
 ff = { version = "0.4", features = ["derive"] }
 blake2b_simd = "0.4.1"
+serde = { version = "1.0", optional = true, features = ["derive"] }
 
 [features]
 unstable-features = ["expose-arith"]
 expose-arith = []
 default = []
+
+[dev-dependencies]
+serde_json = "1.0"

src/bls12_381/fq12.rs

@@ -6,6 +6,7 @@ use rand::{Rand, Rng};
 
 /// An element of Fq12, represented by c0 + c1 * w.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Fq12 {
     pub c0: Fq6,
     pub c1: Fq6,

src/bls12_381/fq2.rs

@@ -7,6 +7,7 @@ use std::cmp::Ordering;
 
 /// An element of Fq2, represented by c0 + c1 * u.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Fq2 {
     pub c0: Fq,
     pub c1: Fq,

src/bls12_381/fq6.rs

@@ -5,6 +5,7 @@ use rand::{Rand, Rng};
 
 /// An element of Fq6, represented by c0 + c1 * v + c2 * v^(2).
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Fq6 {
     pub c0: Fq2,
     pub c1: Fq2,

src/bls12_381/mod.rs

@@ -5,6 +5,8 @@ mod fq2;
 mod fq6;
 mod fr;
 
+#[cfg(feature = "serde")]
+mod serde_impl;
 #[cfg(test)]
 mod tests;
 

src/bls12_381/serde_impl.rs

@@ -0,0 +1,203 @@
+use std::fmt;
+use std::marker::PhantomData;
+
+use super::{Fq, FqRepr, Fr, FrRepr, G1Affine, G2Affine, G1, G2};
+use {CurveAffine, CurveProjective, EncodedPoint, PrimeField};
+
+use serde::de::{Error as DeserializeError, SeqAccess, Visitor};
+use serde::ser::SerializeTuple;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+const ERR_CODE: &str = "deserialized bytes don't encode a group element";
+
+impl Serialize for G1 {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.into_affine().serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for G1 {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(G1Affine::deserialize(d)?.into_projective())
+    }
+}
+
+impl Serialize for G1Affine {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        serialize_affine(self, s)
+    }
+}
+
+impl<'de> Deserialize<'de> for G1Affine {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(deserialize_affine(d)?)
+    }
+}
+
+impl Serialize for G2 {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.into_affine().serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for G2 {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(G2Affine::deserialize(d)?.into_projective())
+    }
+}
+
+impl Serialize for G2Affine {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        serialize_affine(self, s)
+    }
+}
+
+impl<'de> Deserialize<'de> for G2Affine {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(deserialize_affine(d)?)
+    }
+}
+
+/// Serializes a group element using its compressed representation.
+fn serialize_affine<S: Serializer, C: CurveAffine>(c: &C, s: S) -> Result<S::Ok, S::Error> {
+    let len = C::Compressed::size();
+    let mut tup = s.serialize_tuple(len)?;
+    for byte in c.into_compressed().as_ref() {
+        tup.serialize_element(byte)?;
+    }
+    tup.end()
+}
+
+/// Deserializes the compressed representation of a group element.
+fn deserialize_affine<'de, D: Deserializer<'de>, C: CurveAffine>(d: D) -> Result<C, D::Error> {
+    struct TupleVisitor<C> {
+        _ph: PhantomData<C>,
+    }
+
+    impl<'de, C: CurveAffine> Visitor<'de> for TupleVisitor<C> {
+        type Value = C;
+
+        fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            let len = C::Compressed::size();
+            write!(f, "a tuple of size {}", len)
+        }
+
+        #[inline]
+        fn visit_seq<A: SeqAccess<'de>>(self, mut seq: A) -> Result<C, A::Error> {
+            let mut compressed = C::Compressed::empty();
+            for (i, byte) in compressed.as_mut().iter_mut().enumerate() {
+                let len_err = || DeserializeError::invalid_length(i, &self);
+                *byte = seq.next_element()?.ok_or_else(len_err)?;
+            }
+            let to_err = |_| DeserializeError::custom(ERR_CODE);
+            compressed.into_affine().map_err(to_err)
+        }
+    }
+
+    let len = C::Compressed::size();
+    d.deserialize_tuple(len, TupleVisitor { _ph: PhantomData })
+}
+
+impl Serialize for Fr {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.into_repr().serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for Fr {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Fr::from_repr(FrRepr::deserialize(d)?).map_err(|_| D::Error::custom(ERR_CODE))
+    }
+}
+
+impl Serialize for FrRepr {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.0.serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for FrRepr {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(FrRepr(<_>::deserialize(d)?))
+    }
+}
+
+impl Serialize for Fq {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.into_repr().serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for Fq {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Fq::from_repr(FqRepr::deserialize(d)?).map_err(|_| D::Error::custom(ERR_CODE))
+    }
+}
+
+impl Serialize for FqRepr {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        self.0.serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for FqRepr {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Ok(FqRepr(<_>::deserialize(d)?))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    extern crate serde_json;
+
+    use super::*;
+    use bls12_381::Fq12;
+
+    use std::fmt::Debug;
+
+    use rand::{Rng, SeedableRng, XorShiftRng};
+
+    fn test_roundtrip<T: Serialize + for<'a> Deserialize<'a> + Debug + PartialEq>(t: &T) {
+        let ser = serde_json::to_vec(t).unwrap();
+        assert_eq!(*t, serde_json::from_slice(&ser).unwrap());
+    }
+
+    #[test]
+    fn serde_g1() {
+        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let g: G1 = rng.gen();
+        test_roundtrip(&g);
+        test_roundtrip(&g.into_affine());
+    }
+
+    #[test]
+    fn serde_g2() {
+        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let g: G2 = rng.gen();
+        test_roundtrip(&g);
+        test_roundtrip(&g.into_affine());
+    }
+
+    #[test]
+    fn serde_fr() {
+        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let f: Fr = rng.gen();
+        test_roundtrip(&f);
+        test_roundtrip(&f.into_repr());
+    }
+
+    #[test]
+    fn serde_fq() {
+        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let f: Fq = rng.gen();
+        test_roundtrip(&f);
+        test_roundtrip(&f.into_repr());
+    }
+
+    #[test]
+    fn serde_fq12() {
+        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let f: Fq12 = rng.gen();
+        test_roundtrip(&f);
+    }
+}

src/lib.rs

@@ -14,9 +14,11 @@
 
 extern crate blake2b_simd;
 extern crate byteorder;
-#[macro_use]
 extern crate ff;
 extern crate rand;
+#[cfg(feature = "serde")]
+#[macro_use(Serialize, Deserialize)]
+extern crate serde;
 
 #[cfg(test)]
 pub mod tests;