using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

​

using System.Security.Cryptography;

using System.Text;

​

​

public class Downloader

    {

        public static string ByteArrayToHexString(byte[] byteArray)

        {

            string hexString = BitConverter.ToString(byteArray);

​

​

            hexString = hexString.Replace("-", "");

​

            return hexString;

        }

        public static void Main(string[] args)

        {

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            byte[] finalData = GenURL(3599689,"b29da881b5507b49e0d19957805d57ec",7,1);

            Console.WriteLine("Final Data:");

            foreach (var b in finalData)

            {

                Console.Write($"0x{b:x2} ");

            }

            Console.WriteLine();

            Console.WriteLine(finalData.Length);

            Console.WriteLine("AS COMBINED");

            Console.WriteLine(ByteArrayToHexString(finalData));

            Console.WriteLine("encrypting");

            var encrypt = genAESCrypt(finalData,Encoding.UTF8.GetBytes("jo6aey6haid2Teih"));

            Console.WriteLine(ByteArrayToHexString(encrypt));

            foreach (var b in encrypt)

            {

                Console.Write($"0x{b:x2} ");

            }

​

        }

​

        public static byte[] genAESCrypt(byte[] data, byte[] key)

        {

            using Aes myAes = Aes.Create();

            myAes.Mode = CipherMode.ECB;

            myAes.Key = key;

            myAes.Padding = PaddingMode.None;

            var encryptor = myAes.CreateEncryptor(myAes.Key, myAes.IV);

            var encryptedBytes = encryptor.TransformFinalBlock(data, 0, data.Length);

            return encryptedBytes;

        }

​

        public static byte[] GenURL(int trackID, string track_hash, int mediaver, int fmt)

        {

            MD5 md5 = MD5.Create();

            byte[] md5originBytes = Encoding.UTF8.GetBytes(track_hash);

            byte[] fmtBytes = Encoding.UTF8.GetBytes(fmt.ToString());

            byte[] songidBytes = Encoding.UTF8.GetBytes(trackID.ToString());

            byte[] mediaverBytes = Encoding.UTF8.GetBytes(mediaver.ToString());

            byte[] a4Byte = { 0xa4 };

            List<byte[]> concatbyteArrayList = new List<byte[]>

            {

                md5originBytes,

                fmtBytes,

                songidBytes,

                mediaverBytes

            };

            var data_concat = ArrayJoin(a4Byte[0],concatbyteArrayList);

            List<byte[]> byteArrayList = new List<byte[]>

            {

                md5.ComputeHash(data_concat),

                data_concat

            };

            var data = ArrayJoin(a4Byte[0], byteArrayList);

            byte[] append = new byte[data.Length + 1];

            Buffer.BlockCopy(data, 0, append, 0, data.Length);

            append[append.Length - 1] = a4Byte[0];

            int blockSize = 16;

            int length = append.Length;

​

            int paddingNeeded = (blockSize - (length % blockSize)) % blockSize;

​

            byte[] paddedData = new byte[length + paddingNeeded];

            Buffer.BlockCopy(append, 0, paddedData, 0, length);

            Console.WriteLine("md5originBytes: " + BitConverter.ToString(md5originBytes));

            Console.WriteLine("fmtBytes: " + BitConverter.ToString(fmtBytes));

            Console.WriteLine("songidBytes: " + BitConverter.ToString(songidBytes));

            Console.WriteLine("mediaverBytes: " + BitConverter.ToString(mediaverBytes));

            Console.WriteLine("data_concat: " + BitConverter.ToString(data_concat));

            Console.WriteLine("md5Hash: " + BitConverter.ToString(md5.ComputeHash(data_concat)));

            Console.WriteLine("data: " + BitConverter.ToString(data));

            Console.WriteLine("append: " + BitConverter.ToString(append));

            Console.WriteLine("paddedData: " + BitConverter.ToString(paddedData));

            Console.WriteLine("Length: " + paddedData.Length);

            return paddedData;

        }

        public static byte[] ArrayJoin(byte separator, List<byte[]> arrays)

        {

            using (MemoryStream result = new MemoryStream())

            {

                byte[] first = arrays.First();

                result.Write(first, 0, first.Length);

                foreach (var array in arrays.Skip(1))

                {

                    result.WriteByte(separator);

                    result.Write(array, 0, array.Length);

                }

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                return result.ToArray();

            }

        }

​

    }