public static byte[] DecryptBCAT(byte[] data, ulong TitleID, string passStr)
{
byte[] dec;
using (MemoryStream ms = new MemoryStream(data))
{
BinaryReader br = new BinaryReader(ms);
//read the magic
string magic = Encoding.ASCII.GetString(br.ReadBytes(4));
if (magic != BCAT_MAGIC)
{
throw new Exception("Invalid bcat header!");
}
br.BaseStream.Position++; //unknow
byte crypto = br.ReadByte();
byte rsaType = br.ReadByte();
byte secretIndex = br.ReadByte();
br.BaseStream.Position += 8; //padding
byte[] iv = br.ReadBytes(0x10);
byte[] rsa = br.ReadBytes(0x100);
byte[] enc = br.ReadBytes((int)(br.BaseStream.Length - 0x120));
if (crypto > 3)
{
return(enc);
}
int kSize = (crypto + 1) * 8;
byte[] salt = Encoding.ASCII.GetBytes(TitleID.ToString("x16") + Program.Config.SaltLower[secretIndex]);
byte[] pass = Encoding.ASCII.GetBytes(passStr);
byte[] key = PBKDF2Sha256GetBytes(kSize, pass, salt, 4096);
dec = AesCrypto.PerformAesCTR(enc, 0, enc.Length, key, iv);
}
return(dec);
}
public static byte[] EncryptBCAT(byte[] data, ulong TitleID, string passStr, byte HashType, byte crypto, byte[] signature)
{
byte[] output;
using (MemoryStream ms = new MemoryStream())
{
BinaryWriter bw = new BinaryWriter(ms);
Random rnd = new Random();
byte[] iv = new byte[0x10];
rnd.NextBytes(iv); //generate random iv
int secretIndex = rnd.Next(0, 31); //generate random secret index
bw.Write(Encoding.ASCII.GetBytes(BCAT_MAGIC));
bw.Write((byte)1); //must be 1 for some reasons
bw.Write(crypto);
bw.Write(HashType);
bw.Write((byte)secretIndex);
bw.Write(new byte[8]); //padding
bw.Write(iv);
bw.Write(signature);
if (crypto > 3)
{
bw.Write(data);
}
else
{
int kSize = (crypto + 1) * 8;
byte[] salt = Encoding.ASCII.GetBytes(TitleID.ToString("x16") + Program.Config.SaltLower[secretIndex]);
byte[] pass = Encoding.ASCII.GetBytes(passStr);
byte[] key = PBKDF2Sha256GetBytes(kSize, pass, salt, 4096);
bw.Write(AesCrypto.PerformAesCTR(data, 0, data.Length, key, iv));
}
output = ms.ToArray();
}
return(output);
}
