private string SignKey(byte[] publicKey, KeyPair identKey, byte[] expireTimestamp) { byte[] empKeyWithTimestamp = Encrypt.ConcatBytes(publicKey, expireTimestamp); //Logger.Log ("unsinged key: " +JsonUtility.ToJson( new KeyPair(expireTimestamp,empKeyWithTimestamp)) ); byte[] signedOneTimeKey = Encrypt.SignByte(empKeyWithTimestamp, identKey); return(Convert.ToBase64String(signedOneTimeKey)); }