/// <summary>
/// Process secure area in the DS/DSi file
/// </summary>
/// <param name="ndsHeader">NDS header representing the DS file</param>
/// <param name="reader">BinaryReader representing the input stream</param>
/// <param name="writer">BinaryWriter representing the output stream</param>
private void ProcessSecureArea(NDSHeader ndsHeader, BinaryReader reader, BinaryWriter writer)
{
// If we're forcing the operation, tell the user
if (decryptArgs.Force)
{
Console.WriteLine("File is not verified due to force flag being set.");
}
// If we're not forcing the operation, check to see if we should be proceeding
else
{
bool?isDecrypted = CheckIfDecrypted(reader);
if (isDecrypted == null)
{
Console.WriteLine("File has an empty secure area, cannot proceed");
return;
}
else if (decryptArgs.Encrypt ^ isDecrypted.Value)
{
Console.WriteLine("File is already " + (decryptArgs.Encrypt ? "encrypted" : "decrypted"));
return;
}
}
ProcessARM9(ndsHeader, reader, writer);
Console.WriteLine("File has been " + (decryptArgs.Encrypt ? "encrypted" : "decrypted"));
}
/// <summary>
/// First common initialization step
/// </summary>
/// <param name="ndsHeader">NDS header representing the DS file</param>
private void Init1(NDSHeader ndsHeader)
{
Buffer.BlockCopy(Constants.NDSEncryptionData, 0, cardHash, 0, 4 * (1024 + 18));
arg2 = new uint[] { ndsHeader.Gamecode, ndsHeader.Gamecode >> 1, ndsHeader.Gamecode << 1 };
Init2();
Init2();
}
/// <summary>
/// Process an input file given the input values
/// </summary>
public bool ProcessFile()
{
try
{
// Open the read and write on the same file for inplace processing
using (BinaryReader reader = new BinaryReader(File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)))
using (BinaryWriter writer = new BinaryWriter(File.Open(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite)))
{
NDSHeader header = NDSHeader.Read(reader);
if (header == null)
{
Console.WriteLine("Error: Not a DS or DSi Rom!");
return(false);
}
// Process the secure area
ProcessSecureArea(header, reader, writer);
}
return(true);
}
catch
{
Console.WriteLine($"An error has occurred. {filename} may be corrupted if it was partially processed.");
Console.WriteLine("Please check that the file was a valid DS or DSi file and try again.");
return(false);
}
}
/// <summary>
/// Process the secure ARM9 region of the file, if possible
/// </summary>
/// <param name="ndsHeader">NDS header representing the DS file</param>
/// <param name="reader">BinaryReader representing the input stream</param>
/// <param name="writer">BinaryWriter representing the output stream</param>
private void ProcessARM9(NDSHeader ndsHeader, BinaryReader reader, BinaryWriter writer)
{
// Seek to the beginning of the secure area
reader.BaseStream.Seek(0x4000, SeekOrigin.Begin);
writer.BaseStream.Seek(0x4000, SeekOrigin.Begin);
// Grab the first two blocks
uint p0 = reader.ReadUInt32();
uint p1 = reader.ReadUInt32();
// Perform the initialization steps
Init1(ndsHeader);
if (!decryptArgs.Encrypt)
{
Decrypt(ref p1, ref p0);
}
arg2[1] <<= 1;
arg2[2] >>= 1;
Init2();
// If we're decrypting, set the proper flags
if (!decryptArgs.Encrypt)
{
Decrypt(ref p1, ref p0);
if (p0 == Constants.MAGIC30 && p1 == Constants.MAGIC34)
{
p0 = 0xE7FFDEFF;
p1 = 0xE7FFDEFF;
}
writer.Write(p0);
writer.Write(p1);
}
// Ensure alignment
reader.BaseStream.Seek(0x4008, SeekOrigin.Begin);
writer.BaseStream.Seek(0x4008, SeekOrigin.Begin);
// Loop throgh the main encryption step
uint size = 0x800 - 8;
while (size > 0)
{
p0 = reader.ReadUInt32();
p1 = reader.ReadUInt32();
if (decryptArgs.Encrypt)
{
Encrypt(ref p1, ref p0);
}
else
{
Decrypt(ref p1, ref p0);
}
writer.Write(p0);
writer.Write(p1);
size -= 8;
}
// Replace the header explicitly if we're encrypting
if (decryptArgs.Encrypt)
{
reader.BaseStream.Seek(0x4000, SeekOrigin.Begin);
writer.BaseStream.Seek(0x4000, SeekOrigin.Begin);
p0 = reader.ReadUInt32();
p1 = reader.ReadUInt32();
if (p0 == 0xE7FFDEFF && p1 == 0xE7FFDEFF)
{
p0 = Constants.MAGIC30;
p1 = Constants.MAGIC34;
}
Encrypt(ref p1, ref p0);
Init1(ndsHeader);
Encrypt(ref p1, ref p0);
writer.Write(p0);
writer.Write(p1);
}
}
