MD5加密

 public class MD5
    {
        /// <summary>
        /// 32位MD5加密
        /// </summary>
        /// <param name="str">待加密字符</param>
        /// <returns></returns>
        public static string GetMD5_32(string str)
        {
            //32位加密  
            if (string.IsNullOrEmpty(str))
            {
                return "";
            }
            else
            {
                return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5");
            }
        }
        /// <summary>
        /// 16位MD5加密（取32位加密的9~25字符）
        /// </summary>
        /// <param name="str">待加密字符</param>
        /// <returns></returns>
        public static string GetMD5_16(string str)
        {
            if (string.IsNullOrEmpty(str))
            {
                return "";
            }
            else
            {
                return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower().Substring(8, 16);
            }
        }
    }