Merge pull request #2 from dfns/serde

Add `serde` support

Cargo.toml

@@ -13,6 +13,8 @@ sha2 = { version = "0.10", default-features = false }
 subtle = { version = "2", default-features = false }
 generic-array = "0.14"
 
+serde = { version = "1", default-features = false, features = ["derive"], optional = true }
+
 [dev-dependencies]
 hex-literal = "0.4"
 
@@ -21,6 +23,7 @@ std = []
 curve-secp256k1 = ["generic-ec/curve-secp256k1"]
 curve-secp256r1 = ["generic-ec/curve-secp256r1"]
 all-curves = ["curve-secp256k1", "curve-secp256r1"]
+serde = ["dep:serde", "generic-ec/serde"]
 
 [[test]]
 name = "test_vectors"

src/lib.rs

@@ -86,6 +86,8 @@ pub const H: u32 = 1 << 31;
 
 /// Child index, whether hardened or not
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize), serde(into = "u32"))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize), serde(from = "u32"))]
 pub enum ChildIndex {
     /// Hardened index
     Hardened(HardenedIndex),
@@ -95,14 +97,23 @@ pub enum ChildIndex {
 
 /// Child index in range $2^{31} \le i < 2^{32}$ corresponing to a hardened wallet
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize), serde(into = "u32"))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize), serde(try_from = "u32"))]
 pub struct HardenedIndex(u32);
 
 /// Child index in range $0 \le i < 2^{31}$ corresponing to a non-hardened wallet
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize), serde(into = "u32"))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize), serde(try_from = "u32"))]
 pub struct NonHardenedIndex(u32);
 
 /// Extended public key
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(
+    feature = "serde",
+    derive(serde::Serialize, serde::Deserialize),
+    serde(bound = "")
+)]
 pub struct ExtendedPublicKey<E: Curve> {
     /// The public key that can be used for signature verification
     pub public_key: Point<E>,
@@ -112,6 +123,11 @@ pub struct ExtendedPublicKey<E: Curve> {
 
 /// Extended secret key
 #[derive(Clone, Debug)]
+#[cfg_attr(
+    feature = "serde",
+    derive(serde::Serialize, serde::Deserialize),
+    serde(bound = "")
+)]
 pub struct ExtendedSecretKey<E: Curve> {
     /// The secret key that can be used for signing
     pub secret_key: SecretScalar<E>,
@@ -131,6 +147,11 @@ pub struct ExtendedKeyPair<E: Curve> {
 /// It contains an already derived child public key as it needs to be derived
 /// in process of calculating the shift value
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(
+    feature = "serde",
+    derive(serde::Serialize, serde::Deserialize),
+    serde(bound = "")
+)]
 pub struct DerivedShift<E: Curve> {
     /// Derived shift
     pub shift: Scalar<E>,
@@ -200,6 +221,24 @@ impl TryFrom<u32> for NonHardenedIndex {
         }
     }
 }
+impl From<ChildIndex> for u32 {
+    fn from(value: ChildIndex) -> Self {
+        match value {
+            ChildIndex::Hardened(v) => v.0,
+            ChildIndex::NonHardened(v) => v.0,
+        }
+    }
+}
+impl From<HardenedIndex> for u32 {
+    fn from(value: HardenedIndex) -> Self {
+        value.0
+    }
+}
+impl From<NonHardenedIndex> for u32 {
+    fn from(value: NonHardenedIndex) -> Self {
+        value.0
+    }
+}
 impl core::str::FromStr for ChildIndex {
     type Err = core::num::ParseIntError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -261,6 +300,27 @@ impl<E: Curve> ExtendedKeyPair<E> {
     }
 }
 
+#[cfg(feature = "serde")]
+impl<E: Curve> serde::Serialize for ExtendedKeyPair<E> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        self.secret_key.serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de, E: Curve> serde::Deserialize<'de> for ExtendedKeyPair<E> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let secret_key = ExtendedSecretKey::<E>::deserialize(deserializer)?;
+        Ok(secret_key.into())
+    }
+}
+
 /// Marker for a curve supported by SLIP10 specs and this library
 ///
 /// Only implement this trait for the curves that are supported by SLIP10 specs.