1 files changed, 29 insertions, 1 deletions
diff --git a/src/vapid/ser.rs b/src/vapid/ser.rs
index f5372c8..02c77e1 100644
--- a/src/vapid/ser.rs
+++ b/src/vapid/ser.rs
@@ -1,7 +1,9 @@
 pub mod key {
+    use std::fmt;
+
     use base64::{Engine as _, engine::general_purpose::URL_SAFE};
     use p256::ecdsa::VerifyingKey;
-    use serde::Serialize as _;
+    use serde::{Deserializer, Serialize as _, de};
 
     // This serialization - to a URL-safe base-64-encoded string and back - is based on my best
     // understanding of RFC 8292 and the corresponding browser APIs. Particularly, it's based on
@@ -32,4 +34,30 @@ pub mod key {
         let key = URL_SAFE.encode(key);
         key.serialize(serializer)
     }
+
+    pub fn deserialize<'de, D>(deserializer: D) -> Result<VerifyingKey, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_str(Visitor)
+    }
+
+    struct Visitor;
+    impl de::Visitor<'_> for Visitor {
+        type Value = VerifyingKey;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("a string containing a VAPID key")
+        }
+
+        fn visit_str<E>(self, key: &str) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            let key = URL_SAFE.decode(key).map_err(E::custom)?;
+            let key = VerifyingKey::from_sec1_bytes(&key).map_err(E::custom)?;
+
+            Ok(key)
+        }
+    }
 }