cosmrs: add TryFrom impls for tendermint public key types (#203)

Author: cbrit

cosmrs/src/crypto/public_key.rs

@@ -101,22 +101,36 @@ impl TryFrom<&Any> for PublicKey {
     type Error = ErrorReport;
 
     fn try_from(any: &Any) -> Result<PublicKey> {
-        let tm_key = match any.type_url.as_str() {
+        match any.type_url.as_str() {
             Self::ED25519_TYPE_URL => {
-                let proto = proto::cosmos::crypto::ed25519::PubKey::decode(&*any.value)?;
-                tendermint::PublicKey::from_raw_ed25519(&proto.key)
+                proto::cosmos::crypto::ed25519::PubKey::decode(&*any.value)?.try_into()
             }
             Self::SECP256K1_TYPE_URL => {
-                let proto = proto::cosmos::crypto::secp256k1::PubKey::decode(&*any.value)?;
-                tendermint::PublicKey::from_raw_secp256k1(&proto.key)
+                proto::cosmos::crypto::secp256k1::PubKey::decode(&*any.value)?.try_into()
             }
-            other => {
-                return Err(Error::Crypto)
-                    .wrap_err_with(|| format!("invalid type URL for public key: {}", other))
-            }
-        };
+            other => Err(Error::Crypto)
+                .wrap_err_with(|| format!("invalid type URL for public key: {}", other)),
+        }
+    }
+}
 
-        tm_key.map(Into::into).ok_or_else(|| Error::Crypto.into())
+impl TryFrom<proto::cosmos::crypto::ed25519::PubKey> for PublicKey {
+    type Error = ErrorReport;
+
+    fn try_from(public_key: proto::cosmos::crypto::ed25519::PubKey) -> Result<PublicKey> {
+        tendermint::public_key::PublicKey::from_raw_ed25519(&public_key.key)
+            .map(Into::into)
+            .ok_or_else(|| Error::Crypto.into())
+    }
+}
+
+impl TryFrom<proto::cosmos::crypto::secp256k1::PubKey> for PublicKey {
+    type Error = ErrorReport;
+
+    fn try_from(public_key: proto::cosmos::crypto::secp256k1::PubKey) -> Result<PublicKey> {
+        tendermint::public_key::PublicKey::from_raw_secp256k1(&public_key.key)
+            .map(Into::into)
+            .ok_or_else(|| Error::Crypto.into())
     }
 }
 
@@ -217,6 +231,12 @@ mod tests {
     #[test]
     fn json_round_trip() {
         let example_key = EXAMPLE_JSON.parse::<PublicKey>().unwrap();
+
+        // test try_from
+        let tm_key: tendermint::public_key::PublicKey =
+            example_key.try_into().expect("try_into failure");
+        let example_key = PublicKey::try_from(tm_key).expect("try_from failure");
+
         assert_eq!(example_key.type_url(), "/cosmos.crypto.ed25519.PubKey");
         assert_eq!(
             example_key.to_bytes().as_slice(),