asp.net中的md5加密

public 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) ;
}

if(code==32) //32位加密
{
return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str,"MD5").ToLower();
}

return "00000000000000000000000000000000";
}