From 43e6ededf8882a03fccba60421575415be6da5d3 Mon Sep 17 00:00:00 2001
From: peg <peg@magmacollective.org>
Date: Sat, 18 Nov 2023 09:45:49 +0100
Subject: [PATCH] Add a keyshare type for wasm which wraps
 `synedrion::KeyShare` (#512)

* Add a keyshare type for wasm which wraps synedrion::KeyShare

* Update nodejs test script

* Rm comments
---
 crypto/protocol/nodejs-test/index.js |  7 +--
 crypto/protocol/src/user/wasm.rs     | 70 +++++++++++++++++++++++-----
 2 files changed, 63 insertions(+), 14 deletions(-)

diff --git a/crypto/protocol/nodejs-test/index.js b/crypto/protocol/nodejs-test/index.js
index ec5e48ec6..aa940a867 100644
--- a/crypto/protocol/nodejs-test/index.js
+++ b/crypto/protocol/nodejs-test/index.js
@@ -33,14 +33,15 @@ try {
 
 switch(process.argv[2].toLowerCase()) {
     case 'register':
-        protocol.run_dkg_protocol(input.validators_info, input.user_sig_req_seed, input.x25519_private_key).then((output) => {
-          console.log(output)
+        protocol.run_dkg_protocol(input.validators_info, input.user_sig_req_seed, input.x25519_private_key).then((keyShare) => {
+          console.log(keyShare.toString())
         }).catch((err) => {
           console.error('ERR', err)
         })
         break
     case 'sign':
-        protocol.run_signing_protocol(input.key_share, input.sig_uid, input.validators_info, input.user_sig_req_seed, input.x25519_private_key).then((output) => {
+        let keyShare = protocol.KeyShare.fromString(input.key_share)
+        protocol.run_signing_protocol(keyShare, input.sig_uid, input.validators_info, input.user_sig_req_seed, input.x25519_private_key).then((output) => {
             console.log(output)
         }).catch((err) => {
             console.error('ERR', err)
diff --git a/crypto/protocol/src/user/wasm.rs b/crypto/protocol/src/user/wasm.rs
index 34e3479b6..8238ffe20 100644
--- a/crypto/protocol/src/user/wasm.rs
+++ b/crypto/protocol/src/user/wasm.rs
@@ -2,21 +2,19 @@
 use js_sys::Error;
 use subxt::utils::AccountId32;
 use subxt_signer::sr25519;
-use synedrion::KeyShare;
 use wasm_bindgen::prelude::*;
 use wasm_bindgen_derive::TryFromJsValue;
 
 use super::{user_participates_in_dkg_protocol, user_participates_in_signing_protocol};
 use crate::KeyParams;
 
-/// Run the DKG protocol on the client side
-/// This returns the keypair as a JSON encoded string
+/// Run the DKG protocol on the client side and return a keyshare
 #[cfg_attr(feature = "wasm", wasm_bindgen)]
 pub async fn run_dkg_protocol(
     validators_info_js: ValidatorInfoArray,
     user_signing_keypair_seed: Vec<u8>,
     x25519_private_key_vec: Vec<u8>,
-) -> Result<String, Error> {
+) -> Result<KeyShare, Error> {
     let validators_info = parse_validator_info(validators_info_js)?;
 
     let user_signing_keypair = {
@@ -41,15 +39,14 @@ pub async fn run_dkg_protocol(
     .await
     .map_err(|err| Error::new(&format!("{}", err)))?;
 
-    Ok(serde_json::to_string(&key_share).map_err(|err| Error::new(&err.to_string()))?)
+    Ok(KeyShare(key_share))
 }
 
 /// Run the signing protocol on the client side
-/// `key_share` is given as a JSON encoded [synedrion::KeyShare]
 /// Returns a recoverable signature as a base64 encoded string
 #[cfg_attr(feature = "wasm", wasm_bindgen)]
 pub async fn run_signing_protocol(
-    key_share: String,
+    key_share: KeyShare,
     sig_uid: String,
     validators_info_js: ValidatorInfoArray,
     user_signing_keypair_seed: Vec<u8>,
@@ -80,11 +77,8 @@ pub async fn run_signing_protocol(
         x25519_private_key_raw.into()
     };
 
-    let key_share: KeyShare<KeyParams> =
-        serde_json::from_str(&key_share).map_err(|err| Error::new(&err.to_string()))?;
-
     let signature = user_participates_in_signing_protocol(
-        &key_share,
+        &key_share.0,
         &sig_uid,
         validators_info,
         &user_signing_keypair,
@@ -177,3 +171,57 @@ fn parse_validator_info(
     }
     Ok(validators_info)
 }
+
+/// Synedrion key share wrapped for wasm
+#[derive(TryFromJsValue)]
+#[wasm_bindgen]
+#[derive(Clone)]
+pub struct KeyShare(synedrion::KeyShare<KeyParams>);
+
+#[wasm_bindgen]
+impl KeyShare {
+    /// Serialize the keyshare to a JSON string
+    #[wasm_bindgen(js_name = toString)]
+    pub fn to_string(&self) -> Result<String, Error> {
+        serde_json::to_string(&self.0).map_err(|err| Error::new(&err.to_string()))
+    }
+
+    /// Deserialize a keyshare from a JSON string
+    #[wasm_bindgen(js_name = fromString)]
+    pub fn from_string(keyshare_json: String) -> Result<KeyShare, Error> {
+        Ok(Self(serde_json::from_str(&keyshare_json).map_err(|err| Error::new(&err.to_string()))?))
+    }
+
+    /// Serialize the keyshare to a Uint8Array
+    #[wasm_bindgen(js_name = toBytes)]
+    pub fn to_bytes(&self) -> Result<Vec<u8>, Error> {
+        bincode::serialize(&self.0).map_err(|err| Error::new(&err.to_string()))
+    }
+
+    /// Deserialize a keyshare from a Uint8Array
+    #[wasm_bindgen(js_name = fromBytes)]
+    pub fn from_bytes(keyshare_serialized: Vec<u8>) -> Result<KeyShare, Error> {
+        Ok(Self(
+            bincode::deserialize(&keyshare_serialized)
+                .map_err(|err| Error::new(&err.to_string()))?,
+        ))
+    }
+
+    /// Get the verifying (public) key associated with this keyshare
+    #[wasm_bindgen(js_name = verifyingKey)]
+    pub fn verifying_key(&self) -> Vec<u8> {
+        self.0.verifying_key().to_encoded_point(true).as_bytes().to_vec()
+    }
+
+    /// Get the number of parties asssociated with this keyshare
+    #[wasm_bindgen(js_name = numParties)]
+    pub fn num_parties(&self) -> usize {
+        self.0.num_parties()
+    }
+
+    /// Get the party index of this keyshare (a number indentiying which party we are)
+    #[wasm_bindgen(js_name = partyIndex)]
+    pub fn party_index(&self) -> usize {
+        self.0.party_index().as_usize()
+    }
+}