Code for decrypting Blue Mammoth Games' Brawlhalla's SWZ files

BrawlhallaDumper.zip

BrawlhallaSWZ.cs

// WEll512 implementation - https://gist.github.com/barncastle/0fb2279bdc337d2a7d951e1bd2e3c0df

using Ionic.Zlib;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;

static class BrawlhallaSWZ
{
    public static string[] Decrypt(Stream input, uint globalKey)
    {
        var checksum = ReadUInt32BE(input);
        var seed = ReadUInt32BE(input);

        // initialise WELL512
        var rand = new WELL512(seed ^ globalKey);

        // compute and compare the header checksum
        // this also mixes the WELL512 state so is required
        var hash = 0x2DF4A1CDu;
        var hash_rounds = globalKey % 0x1F + 5;

        for (var i = 0; i < hash_rounds; i++)
            hash ^= rand.NextUInt();

        Debug.Assert(hash == checksum);

        // decrypt each string object
        var results = new List<string>();
        while (input.Position != input.Length)
        {
            if (ReadStringEntry(input, rand, out var stringEntry))
                results.Add(stringEntry);
        }                

        return results.ToArray();
    }

    public static byte[] Encrypt(uint seed, uint globalKey, params string[] stringEntries)
    {
        // initialise WELL512
        var rand = new WELL512(seed ^ globalKey);

        // compute the header checksum
        var hash = 0x2DF4A1CDu;
        var hash_rounds = globalKey % 0x1F + 5;

        for (var i = 0; i < hash_rounds; i++)
            hash ^= rand.NextUInt();

        using var ms = new MemoryStream(0x1000);
        WriteUInt32BE(ms, hash);
        WriteUInt32BE(ms, seed);

        foreach (var entry in stringEntries)
        {
            var stringBytes = Encoding.UTF8.GetBytes(entry);
            WriteStringEntry(stringBytes, rand, ms);
        }  

        return ms.ToArray();
    }

    private static bool ReadStringEntry(Stream input, WELL512 rand, out string result)
    {
        // read the object header XOR'ing the size fields
        var compressedSize = ReadUInt32BE(input) ^ rand.NextUInt();
        var decompressedSize = ReadUInt32BE(input) ^ rand.NextUInt();
        var checksum = ReadUInt32BE(input);

        if (compressedSize + input.Position > input.Length)
        {
            result = null;
            return false;
        }

        // read the compressed data
        var buffer = new byte[compressedSize];
        input.Read(buffer);

        // again required even if not
        // validating the checksum
        var hash = rand.NextUInt();

        for (var i = 0; i < compressedSize; i++)
        {
            // decode the byte
            var shift = i & 0xF;
            buffer[i] ^= (byte)(((0xFFu << shift) & rand.NextUInt()) >> shift);

            // update the local checksum
            hash = buffer[i] ^ RotateRight(hash, i % 7 + 1);
        }

        Debug.Assert(checksum == hash);

        // zlib decompress
        var decompressedData = ZlibStream.UncompressBuffer(buffer);
        result = Encoding.UTF8.GetString(decompressedData);

        return true;
    }

    private static void WriteStringEntry(byte[] input, WELL512 rand, Stream output)
    {
        // zlib compress
        var compressedInput = ZlibStream.CompressBuffer(input);

        // calculate the field values
        var compressedSize = (uint)compressedInput.Length ^ rand.NextUInt();
        var decompressedSize = (uint)input.Length ^ rand.NextUInt();

        // create the checksum
        var checksum = rand.NextUInt();

        for (var i = 0; i < compressedInput.Length; i++)
        {
            // update the checksum
            checksum = compressedInput[i] ^ RotateRight(checksum, i % 7 + 1);

            // encode the byte
            var shift = i & 0xF;
            compressedInput[i] ^= (byte)(((0xFFu << shift) & rand.NextUInt()) >> shift);
        }

        // write the fields and data
        WriteUInt32BE(output, compressedSize);
        WriteUInt32BE(output, decompressedSize);
        WriteUInt32BE(output, checksum);
        output.Write(compressedInput);
    }

    private static uint RotateRight(uint v, int bits)
    {
        return (v >> bits) | (v << (32 - bits));
    }

    private static uint ReadUInt32BE(Stream stream)
    {
        var buffer = new byte[4];
        stream.Read(buffer);
        return (uint)(buffer[3] | (buffer[2] << 8) | (buffer[1] << 16) | (buffer[0] << 24));
    }

    private static void WriteUInt32BE(Stream stream, uint value)
    {
        var buffer = new byte[4]
        {
            (byte)((value >> 24) & 0xFF),
            (byte)((value >> 16) & 0xFF),
            (byte)((value >> 08) & 0xFF),
            (byte)((value >> 00) & 0xFF)
        };

        stream.Write(buffer);
    }
}

Is there a way to reverse the algorithm to create an encryption method? Or is that near impossible because of WELL512?

I've updated the gist with encryption methods.

Since WELL512 is a LFSR, if you provide the same seed it will always produce the same random number at each call - hence why the checksums HAVE to be validated for decryption. Additionally, XOR'ing is a reversable operation. The only real difference between encrypting and decrypting is the order of operations - compress, update checksum, encrypt vs decrypt, update checksum, decompress.

If I wanted to decrypt the swzs, what should I do? Pop this into a compiler then run it?

If I wanted to decrypt the swzs, what should I do? Pop this into a compiler then run it?

I've wrapped this in a simple application for you. Download the zip file, extract the contents anywhere and drag and drop one-or-more swz files onto it. It will prompt for a "global encryption key" which is the value used by ANE_RawData.Init in BrawlhallaAir.swf - currently 124416110 for patch 6.11. It will then create a folder called Dump in the same directory as your swz files and export all the decrypted text files there.

Encrypting and repackaging will require a separate tool and is not something I'd be willing to make however everything required for it is already documented above.

Thank you so much! I completely missed on the zip file ahah :3 However, when I put the global encryption key and then press enter the Dump folder appears, but empty even tho I have some swzs in my folder. Is this normal?

Thank you so much! I completely missed on the zip file ahah :3 However, when I put the global encryption key and then press enter the Dump folder appears, but empty even tho I have some swzs in my folder. Is this normal? edit* second acc cuz forgot password lol

I only uploaded it an hour ago :) Did you drag and drop the swz files onto it?

Ohhh onto the program itself! My b :)
Thanks for uploading it ^^
Sorry for bothering, but is the global encryption key under the ANE_RawData in BHAir.swf? I cant find it, maybe its obfuscated?

Yes it is. Using a flash decompiler (like JPEXS Free Flash Decompiler), you need to locate the ANE_RawData.Init function call within BrawlhallaAir.swf. With FFDec you can simply use the Text Search functionality to find it.

i think i did something wrong, i extracted the zip application, I put the .swz, the encryption key and nothing happened, the program just closed.
it created the "Dump" folder but there was nothing inside

Did you drag and drop the swz files onto the application? If so, it might be a different encryption key is required.

I didn't know it was supposed to drag the file directly into the application, thanks!

I already modified the files I wanted, how do I apply them to the game?

Encrypting and repackaging will require a separate tool and is not something I'd be willing to make however everything required for it is already documented above.

The class implementation has encryption methods that allow you to compile the files into a .swz, but you'll need to build that yourself.
Also be mindful when editing .csv files, as some of the linebreaks they use are LF characters instead of CRLF characters ($0A vs. $0D 0A), and some text editors will squash both of those into one or the other depending on you settings, so be sure to verify the file with a hex editor. This issue is most noticeable with the file headers, the very first line in any .csv file that has the file name.

Also I noticed filenames and extensions aren't preserved when dumping.
The following code takes a file stored as string data and gives the correct string file_name.

string file_name;
if (data[0] == '<')
{
    if (data.Substring(0, 10) == "<LevelDesc") file_name = data.Split("LevelName=\"")[1].Split('"')[0] + ".xml";
    else file_name = data.Substring(1, data.IndexOf('>') - 1) + ".xml";
}
else file_name = data.Substring(0, data.IndexOf('\n')) + ".csv";

@KevitoLegal: As @Talafhah1 explained, this is not something supported nor something I'm interested in doing. To be completely honest, I have no interest in this game - I just like reverse engineering file formats, and part of my process is writing functional snippets of code to help me understand how the logic works. As a byproduct, these snippets (hopefully) document the format and provide other developers a basis to create proper tools from.

The attached app is something I knocked together in a few minutes just to provide something more user-friendly than just code. If @Talafhah1 or anyone else wants to build a proper tool, please feel to use as much or little of my code - consider it licensed as WTFPL :)

Also I noticed filenames and extensions aren't preserved when dumping. The following code takes a file stored as string data and gives the correct string file_name.

string file_name;
if (data[0] == '<')
{
    if (data.Substring(0, 10) == "<LevelDesc") file_name = data.Split("LevelName=\"")[1].Split('"')[0] + ".xml";
    else file_name = data.Substring(1, data.IndexOf('>') - 1) + ".xml";
}
else file_name = data.Substring(0, data.IndexOf('\n')) + ".csv";

Was trying to implement this into a little program but am not able to substitute the data string with anything, man :c

The Decrypt static method is called 4 times, once for each .swz file stream; its output is a string[] that has all the files included in the .swz as a string.
So, simply use a foreach loop on the elements of the output of Decrypt and run the filename block, then use the file_name string in the file stream writer.

i cannot find anything

here 0_O