baidu mp3竟然还加密，太扯了

 public class BaiduHelper
    {

        static int F = 0;
        static string I = "", J = "";
        static string O = "";
        static string E = "";
        static int[] K = new int[1000];
        static int[] H = new int[1000];
        static int M = 0;

        /// <summary>
        /// GetBaiduMp3Url
        /// </summary>
        /// <param name="str"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        public static string GetBaiduMp3Url(String str, int key)
        {
            F = key;
            I = str;
            J = str;
            N(0, 9, 48);
            N(10, 35, 55);
            N(36, 61, 61);

            M = F % 26;
            M = (M > -1) ? M : 1;

            O = A(I);
            E = (I == J) ? O : A(J);
            return E;
        }

        public static void N(int S, int P, int Q)
        {
            for (int R = S; R <= P; R++)
            {
                K[R] = R + Q;
                H[R + Q] = R;
            }
        }

        public static string A(string Q)
        {
            int P = Q.Length;
            string S = "";
            char[] chars = Q.ToCharArray();
            for (int R = 0; R < P; R++) {
                char T = chars[R];
                if (Regex.IsMatch(T.ToString(),"[a-zA-Z0-9]")) {
                    int U = H[chars[R]] - M;
                    if (U < 0) {
                     U += 62 ;
                     }
                    T = (char)(K[U]);//String.fromCharCode
                }
                S += T;
            }
            return S;
        }
    }