MD5加密

public static string EncrptString(string str)
        {
            byte[] buffer = System.Text.Encoding.Default.GetBytes(str);
            MD5 md5 = MD5.Create();
            buffer = md5.ComputeHash(buffer);
            StringBuilder sb = new StringBuilder();
            foreach (var i in buffer)
            {
                sb.Append(i.ToString("x2"));
            }
            return sb.ToString();
        }