json unix timestamp to dateTime

unix timestamp to DateTime.cs

    public class UnixConvert : JsonConverter
    {
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            var time = ToUnixTimestamp((DateTime) value);
            writer.WriteValue(time);
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            long unixTimeStamp = long.Parse(reader.Value.ToString());
            return UnixTimeStampToDateTime(unixTimeStamp);
        }

        public override bool CanConvert(Type objectType)
        {
            return true;
        }

        private static DateTime UnixTimeStampToDateTime(long unixTimeStamp)
        {
            System.DateTime dtDateTime = new System.DateTime(1970, 1, 1, 0, 0, 0, 0);
            dtDateTime = dtDateTime.AddSeconds(unixTimeStamp);
            return dtDateTime;
        }

        public static long ToUnixTimestamp(DateTime time)
        {
            var date = new DateTime(1970, 1, 1, 0, 0, 0, time.Kind);
            var unixTimestamp = System.Convert.ToInt64((time - date).TotalSeconds);

            return unixTimestamp;
        }
    }