C# MD5加密字符串

using System.Security.Cryptography;

static string md5(string str, int code)
{
if (code == 16) //16位MD5加密（取32位加密的9~25字符）
{
return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower().Substring(8, 16);
}
else//32位加密
{
return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower();
}
}