Class FileDecryptor

StaticData/NikkeStaticData/Program.cs:10–170

namespace NikkeStaticData;

public static class FileDecryptor
{
	static HttpClient client = new HttpClient();
	private static readonly string url = "https://global-lobby.nikke-kr.com/v1/get-static-data-pack-info-mpk";

	static async Task Main(string[] args)
	{
		Console.WriteLine($"Fetching url...");
		byte[] encodedBytes = await GetProtoBytes();
		ResStaticDataPackInfo resStaticDataPackInfo = ResStaticDataPackInfo.ParseFrom(encodedBytes);

		Console.WriteLine($"Got response, latest version is {resStaticDataPackInfo.Version}");

		Console.WriteLine($"Downloading StaticData.pack...");
		byte[] fileBytes = await GetStaticDataBytes(resStaticDataPackInfo.Url);

		byte[] password = Convert.FromBase64String(
			"y8Icb/P1B/UFusrUmCiEH/DROMdh39bmZJqFEz4aagxoDivE33L4xlXkexQ2GDun0SCBItGpGIRlEwvtowDl2Q=="
		);

		byte[] key1 = new Rfc2898DeriveBytes(password, resStaticDataPackInfo.Salt1, 10000, HashAlgorithmName.SHA256).GetBytes(32);
		byte[] key2 = new Rfc2898DeriveBytes(password, resStaticDataPackInfo.Salt2, 10000, HashAlgorithmName.SHA256).GetBytes(32);

		Console.WriteLine($"Got keys, decrypting (part 1)...");
		byte[] part1 = DecryptData(fileBytes, key2);
		byte[] innerEncrypted;
		using (var part1Stream = new MemoryStream(part1))
		using (var zip = new ZipArchive(part1Stream, ZipArchiveMode.Read))
		{
			var entry = zip.Entries.First(e => e.Name == "data"); // or whatever the file is named
			using var entryStream = entry.Open();
			using var ms = new MemoryStream();
			entryStream.CopyTo(ms);
			innerEncrypted = ms.ToArray();
		}

		Console.WriteLine($"Got keys, decrypting (part 2)...");
		byte[] finalZipBytes = DecryptData(innerEncrypted, key1, ctr: true);

		Console.WriteLine($"Decrypted! Saving...");
		File.WriteAllBytes($"StaticData.zip", finalZipBytes);
		Console.WriteLine($"Done.");
	}

	static async Task<byte[]> GetStaticDataBytes(string url)
	{
		using var httpClient = new HttpClient();
		var fileBytes = await httpClient.GetByteArrayAsync(url).ConfigureAwait(false);
		return fileBytes;
	}

	static async Task<byte[]> GetProtoBytes()
	{
		var handler = new SocketsHttpHandler
		{
			ConnectCallback = async (context, cancellationToken) =>
			{
				var socket = new Socket(SocketType.Stream, ProtocolType.Tcp) { NoDelay = true };