NeteaseMusicEncryptionHandler.cs

using System.IO;
using System.Linq;
using System.Numerics;
using System.Security.Cryptography;
using System.Text;
using System;

namespace MusicBeePlugin
{
    /*
     * Adopted from https://github.com/real-zony/ZonyLrcToolsX/blob/dev/src/ZonyLrcTools.Common/Infrastructure/Encryption/NetEaseMusicEncryptionHelper.cs
     * (MIT License)
     * and  https://github.com/jitwxs/163MusicLyrics/blob/master/MusicLyricApp/Api/Music/NetEaseMusicNativeApi.cs
     * and  https://github.com/mos9527/pyncm/blob/ad0a84b2ed5f1affa9890d5f54f6170c2cf99bbb/pyncm/utils/crypto.py#L53
     */
    internal static class NeteaseMusicEncryptionHelper
    {
        private const string Modulus =
            "00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7";

        internal const string Nonce = "0CoJUm6Qyw8W8jud";
        private const string PubKey = "010001";
        private const string Vi = "0102030405060708";
        private static readonly byte[] ID_XOR_KEY_1 = Encoding.UTF8.GetBytes("3go8&$8*3*3h0k(2)2");

        public static string RsaEncode(string text)
        {
            var srText = new string(text.Reverse().ToArray());
            var a = BCHexDec(BitConverter.ToString(Encoding.Default.GetBytes(srText)).Replace("-", string.Empty));
            var b = BCHexDec(PubKey);
            var c = BCHexDec(Modulus);
            var key = BigInteger.ModPow(a, b, c).ToString("x");
            key = key.PadLeft(256, '0');

            return key.Length > 256 ? key.Substring(key.Length - 256, 256) : key;
        }

        public static BigInteger BCHexDec(string hex)
        {
            var dec = new BigInteger(0);
            var len = hex.Length;

            for (var i = 0; i < len; i++)
            {
                dec += BigInteger.Multiply(new BigInteger(Convert.ToInt32(hex[i].ToString(), 16)),
                    BigInteger.Pow(new BigInteger(16), len - i - 1));
            }

            return dec;
        }

        public static string AesEncode(string secretData, string secret = "TA3YiYCfY2dDJQgg")
        {
            byte[] encrypted;
            var iv = Encoding.UTF8.GetBytes(Vi);

            using (var aes = Aes.Create())
            {
                aes.Key = Encoding.UTF8.GetBytes(secret);
                aes.IV = iv;
                aes.Mode = CipherMode.CBC;
                using (var encryptor = aes.CreateEncryptor())
                {
                    using (var stream = new MemoryStream())
                    {
                        using (var cryptoStream = new CryptoStream(stream, encryptor, CryptoStreamMode.Write))
                        {
                            using (var sw = new StreamWriter(cryptoStream))
                            {
                                sw.Write(secretData);
                            }

                            encrypted = stream.ToArray();
                        }
                    }
                }
            }

            return Convert.ToBase64String(encrypted);
        }

        public static string CreateSecretKey(int length)
        {
            const string str = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
            var sb = new StringBuilder(length);
            var rnd = new Random();

            for (var i = 0; i < length; ++i)
            {
                sb.Append(str[rnd.Next(0, str.Length)]);
            }

            return sb.ToString();
        }

        public static string CloudMusicDllEncode(string deviceId)
        {
            var xored = new byte[deviceId.Length];
            for (var i = 0; i < deviceId.Length; i++)
            {
                xored[i] = (byte)(deviceId[i] ^ ID_XOR_KEY_1[i % ID_XOR_KEY_1.Length]);
            }

            using (var md5 = MD5.Create())
            {
                var digest = md5.ComputeHash(xored);
                return Convert.ToBase64String(digest);
            }
        }
    }
}