static void DecryptApCode(DataStream stream, Configuration config)
{
uint[,] encryptInfo = new uint[, ] {
// seed offset length
{ 0x02175b00, 0x0215d0d8, 0x0215e44c },
{ 0x0216F306, 0x0215D87C, 0x0215E388 },
{ 0x0216D1F2, 0x0215C2F0, 0x0215E3DC },
{ 0x02175760, 0x0215CDA0, 0x0215E44C },
{ 0x0216F5B6, 0x0215DAB4, 0x0215E5F0 },
{ 0x0216D452, 0x0215C528, 0x0215E3DC },
};
for (int i = 0; i < encryptInfo.GetLength(0); i++)
{
uint seed = encryptInfo[i, 0] - config.ConstantOffset - config.AddressOffset;
uint offset = encryptInfo[i, 1] - config.AddressOffset;
uint length = encryptInfo[i, 2] - config.ConstantOffset - config.AddressOffset;
offset -= config.OverlayRamAddress;
using (var input = new DataStream(stream, offset, length))
using (var output = new DataStream(stream, offset, length)) {
Console.WriteLine($"* RC4N {offset:X4}h - {length:X4}h");
Rc4N.Decrypt(seed, input, output);
}
}
}
public static void Decrypt(uint seed, DataStream input, DataStream output)
{
// seed seems to be always the same but the input length is variable
byte[] key = GenerateKey(seed, (uint)input.Length);
var rc4n = new Rc4N(key);
rc4n.Run(input, output);
}