Impl serde ser and deser for bls keypairs

eth2/utils/bls/src/signature.rs

@@ -1,5 +1,8 @@
+use super::serde_vistors::HexVisitor;
 use super::{PublicKey, SecretKey};
 use bls_aggregates::Signature as RawSignature;
+use hex::encode as hex_encode;
+use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use ssz::{
     decode_ssz_list, hash, ssz_encode, Decodable, DecodeError, Encodable, SszStream, TreeHash,
@@ -83,7 +86,19 @@ impl Serialize for Signature {
     where
         S: Serializer,
     {
-        serializer.serialize_bytes(&ssz_encode(self))
+        serializer.serialize_str(&hex_encode(ssz_encode(self)))
+    }
+}
+
+impl<'de> Deserialize<'de> for Signature {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let bytes = deserializer.deserialize_str(HexVisitor)?;
+        let (pubkey, _) = <_>::ssz_decode(&bytes[..], 0)
+            .map_err(|e| serde::de::Error::custom(format!("invalid ssz ({:?})", e)))?;
+        Ok(pubkey)
     }
 }