base shared key on wallet key

lib/client/api.js

@@ -167,7 +167,7 @@ API.prototype._initData = function(network, walletPrivKey, m, n) {
   var xPrivKey = new Bitcore.HDPrivateKey(network);
   var xPubKey = (new Bitcore.HDPublicKey(xPrivKey)).toString();
   var signingPrivKey = (new Bitcore.HDPrivateKey(xPrivKey)).derive('m/1/0').privateKey;
-  var sharedEncryptingKey = Bitcore.crypto.Hash.sha256(signingPrivKey.toBuffer()).slice(0, 16).toString('base64');
+  var sharedEncryptingKey = Bitcore.crypto.Hash.sha256(walletPrivKey.toBuffer()).slice(0, 16).toString('base64');
   var copayerId = WalletUtils.xPubToCopayerId(xPubKey);
 
   var data = {