feat: add serde support (#780)

This (optional) feature implements Serialize/Deserialize for Zeroizing when
the inner type implements these traits. This makes it possible to use
Zeroizing in serde contexts.

Signed-off-by: Nathaniel McCallum <nathaniel@profian.com>

Author: npmccallum

Cargo.lock

@@ -17,6 +17,7 @@ keywords = ["memory", "memset", "secure", "volatile", "zero"]
 edition = "2018"
 
 [dependencies]
+serde = { version = "1.0", default-features = false, optional = true }
 zeroize_derive = { version = "1.3", path = "derive", optional = true }
 
 [features]

zeroize/Cargo.toml

@@ -715,6 +715,34 @@ where
     }
 }
 
+#[cfg(feature = "serde")]
+impl<Z> serde::Serialize for Zeroizing<Z>
+where
+    Z: Zeroize + serde::Serialize,
+{
+    #[inline(always)]
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        self.0.serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de, Z> serde::Deserialize<'de> for Zeroizing<Z>
+where
+    Z: Zeroize + serde::Deserialize<'de>,
+{
+    #[inline(always)]
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        Ok(Self(Z::deserialize(deserializer)?))
+    }
+}
+
 /// Use fences to prevent accesses from being reordered before this
 /// point, which should hopefully help ensure that all accessors
 /// see zeroes after this point.