crypto_kx: use serdect crate

Replaces the handwritten serde visitor implementation with the
same-shaped implementation in the `serdect` crate, similar to the
changes to the `crypto_box` crate in #51.

This reduces the maintenance burden of `serde`-related code, by keeping
all of the complexity and interop testing in the `serdect` crate.

crypto_kx/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "crypto_kx"
-version = "0.1.0-pre" # Also update html_root_url in lib.rs when bumping this
+version = "0.1.0-pre"
 description = "Pure Rust implementation of libsodium's crypto_kx using BLAKE2"
 authors = ["C4DT", "RustCrypto Developers"]
 license = "Apache-2.0 OR MIT"
@@ -16,8 +16,9 @@ rust-version = "1.56"
 [dependencies]
 blake2 = { version = "0.10", default-features = false }
 rand_core = "0.6"
-# renamed to allow having a "serde" feature
-our_serde = { package = "serde", version = "1", optional = true, features = ["derive"] }
+
+# optional dependencies
+serdect = { version = "0.1", optional = true, default-features = false }
 
 [dependencies.x25519-dalek]
 version = "1"
@@ -32,5 +33,5 @@ rand_core = { version = "0.6", features = ["std"] }
 sodiumoxide = "0.2"
 
 [features]
-serde = ["our_serde", "x25519-dalek/serde"]
+serde = ["serdect"]
 std = ["blake2/std", "rand_core/std", "x25519-dalek/std"]

crypto_kx/src/keypair.rs

@@ -4,12 +4,6 @@ use rand_core::{CryptoRng, RngCore};
 use crate::{ClientSessionKeys, PublicKey, SecretKey, ServerSessionKeys, SessionKey};
 
 /// A [`SecretKey`] with its related [`PublicKey`].
-#[derive(Clone)]
-#[cfg_attr(
-    feature = "serde",
-    derive(our_serde::Deserialize, our_serde::Serialize)
-)]
-#[cfg_attr(feature = "serde", serde(crate = "our_serde"))]
 pub struct KeyPair {
     secret: SecretKey,
     public: PublicKey,

crypto_kx/src/keys/public.rs

@@ -2,13 +2,11 @@
 
 use crate::errors::InvalidLength;
 
+#[cfg(feature = "serde")]
+use serdect::serde::{de, ser, Deserialize, Serialize};
+
 /// [`PublicKey`] which can be freely shared.
 #[derive(Clone, Copy, Hash, PartialEq, Eq)]
-#[cfg_attr(
-    feature = "serde",
-    derive(our_serde::Deserialize, our_serde::Serialize)
-)]
-#[cfg_attr(feature = "serde", serde(crate = "our_serde"))]
 pub struct PublicKey(x25519_dalek::PublicKey);
 
 impl PublicKey {
@@ -46,3 +44,25 @@ impl TryFrom<&[u8]> for PublicKey {
         Ok(Self::from(array))
     }
 }
+
+#[cfg(feature = "serde")]
+impl Serialize for PublicKey {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: ser::Serializer,
+    {
+        serdect::array::serialize_hex_upper_or_bin(&self.0.to_bytes(), serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> Deserialize<'de> for PublicKey {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: de::Deserializer<'de>,
+    {
+        let mut bytes = [0u8; Self::BYTES];
+        serdect::array::deserialize_hex_or_bin(&mut bytes, deserializer)?;
+        Self::try_from(bytes.as_slice()).map_err(de::Error::custom)
+    }
+}

crypto_kx/src/keys/secret.rs

@@ -3,13 +3,11 @@
 use crate::errors::InvalidLength;
 use rand_core::{CryptoRng, RngCore};
 
+#[cfg(feature = "serde")]
+use serdect::serde::{de, ser, Deserialize, Serialize};
+
 /// [`SecretKey`] that should be kept private.
 #[derive(Clone)]
-#[cfg_attr(
-    feature = "serde",
-    derive(our_serde::Deserialize, our_serde::Serialize)
-)]
-#[cfg_attr(feature = "serde", serde(crate = "our_serde"))]
 pub struct SecretKey(x25519_dalek::StaticSecret);
 
 impl SecretKey {
@@ -56,3 +54,25 @@ impl TryFrom<&[u8]> for SecretKey {
         Ok(Self::from(array))
     }
 }
+
+#[cfg(feature = "serde")]
+impl Serialize for SecretKey {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: ser::Serializer,
+    {
+        serdect::array::serialize_hex_upper_or_bin(&self.0.to_bytes(), serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> Deserialize<'de> for SecretKey {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: de::Deserializer<'de>,
+    {
+        let mut bytes = [0u8; Self::BYTES];
+        serdect::array::deserialize_hex_or_bin(&mut bytes, deserializer)?;
+        Self::try_from(bytes.as_slice()).map_err(de::Error::custom)
+    }
+}

crypto_kx/src/lib.rs

@@ -49,8 +49,7 @@
 #![no_std]
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg",
-    html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg",
-    html_root_url = "https://docs.rs/crypto_kx/0.0.2"
+    html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg"
 )]
 #![warn(missing_docs, rust_2018_idioms)]