C# 加密算法MD5

#region 字符串md5加密
        /// 

        /// 字符串md5加密
        /// 
        /// 字符串
        /// 长度 16或32
        /// 大写小写 true为小写 false 为大写
        /// 
        public static string MD5(this string _, int length = 32, Boolean ignoreCase = true)
        {
            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
            byte[] data = md5.ComputeHash(Encoding.Default.GetBytes(_));
            string _data = (length == 16 ? BitConverter.ToString(data, 4, 8) : BitConverter.ToString(data, 0, 16)).Replace("-", "");
            return ignoreCase ? _data.ToLower() : _data;
        }
        #endregion