//
// Encrypt a packed cartridge into a crypted cartridge
//
private void Encrypt()
{
_decrypted.CopyTo(_encrypted, 0);
//
// Content
//
byte[] content = new byte[0x40];
Buffer.BlockCopy(_decrypted, 0, content, 0, 0x40);
// Checksum content
Buffer.BlockCopy(Crc16_Checksum.Checksum(content), 0, _encrypted, 0x40, 2);
// Encrypt content
byte[] contentEncrypted = Desx_Crypto.Encrypt(_key, content);
Buffer.BlockCopy(contentEncrypted, 0, _encrypted, 0, 0x40);
// Checksum crypted content
Buffer.BlockCopy(Crc16_Checksum.Checksum(contentEncrypted), 0, _encrypted, 0x46, 2);
//
// Current Material Quantity
//
byte[] currentMaterialQuantity = new byte[8];
Buffer.BlockCopy(_decrypted, 0x58, currentMaterialQuantity, 0, 8);
// Checksum current material quantity
Buffer.BlockCopy(Crc16_Checksum.Checksum(currentMaterialQuantity), 0, _encrypted, 0x62, 2);
// Encrypt current material quantity
byte[] currentMaterialQuantityEncrypted = Desx_Crypto.Encrypt(_key, currentMaterialQuantity);
Buffer.BlockCopy(currentMaterialQuantityEncrypted, 0, _encrypted, 0x58, 8);
// Checksum crypted current material quantity
Buffer.BlockCopy(Crc16_Checksum.Checksum(currentMaterialQuantityEncrypted), 0, _encrypted, 0x60, 2);
}
//
// Decrypt a crypted cartridge into a packed cartridge
//
private void Decrypt()
{
_encrypted.CopyTo(_decrypted, 0);
//
// Content
//
byte[] contentEncrypted = new byte[0x40];
Buffer.BlockCopy(_encrypted, 0, contentEncrypted, 0, 0x40);
// Validate crypted content checksum
if (!Crc16_Checksum.Checksum(contentEncrypted).SequenceEqual(_cryptedContentCRC))
{
throw new Exception("invalid crypted content checksum");
}
// Decrypt content
byte[] content = Desx_Crypto.Decrypt(_key, contentEncrypted);
Buffer.BlockCopy(content, 0, _decrypted, 0, 0x40);
// Validating plaintext checksum
if (!Crc16_Checksum.Checksum(content).SequenceEqual(_plainContentCRC))
{
throw new Exception(
"invalid content checksum: should have " + _plainContentCRC.HexString() +
" but have " + Crc16_Checksum.Checksum(content).HexString());
}
//
// Current Material Quantity
//
byte[] currentMaterialQuantityEncrypted = new byte[8];
Buffer.BlockCopy(_encrypted, 0x58, currentMaterialQuantityEncrypted, 0, 8);
// Validate crypted current material quantity checksum
if (!Crc16_Checksum.Checksum(currentMaterialQuantityEncrypted).SequenceEqual(_currentMaterialQuantityCryptedCRC))
{
throw new Exception("invalid current material quantity checksum");
}
// Decrypt current material quantity
byte[] currentMaterialQuantityDecrypted = Desx_Crypto.Decrypt(_key, currentMaterialQuantityEncrypted);
Buffer.BlockCopy(currentMaterialQuantityDecrypted, 0, _decrypted, 0x58, 8);
// Validating current material quantity checksum
if (!Crc16_Checksum.Checksum(currentMaterialQuantityDecrypted).SequenceEqual(_currentMaterialQuantityCRC))
{
throw new Exception("invalid current material quantity checksum");
}
}
//
// Build a key used to encrypt/decrypt a cartridge
//
private void BuildKey()
{
Buffer.BlockCopy(_encrypted, 0x17, _keyFragment, 0, 8);
if (!Crc16_Checksum.Checksum(_keyFragment, 0x14d0).SequenceEqual(_keyFragmentCRC))
{
throw new Exception("invalid keyfragment checksum: should have " + _keyFragmentCRC.HexString() + " but have " + Crc16_Checksum.Checksum(_keyFragment).HexString());
}
_keyFragment = shuffle_key_fragment(_keyFragment);
byte[] machine_number = _machine.Number;
_key[0] = (byte)(~_eepromUID[3] & 0xff);
_key[1] = (byte)(~machine_number[3] & 0xff);
_key[2] = (byte)(~machine_number[1] & 0xff);
_key[3] = (byte)(~_keyFragment[0] & 0xff);
_key[4] = (byte)(~_keyFragment[1] & 0xff);
_key[5] = (byte)(~_keyFragment[2] & 0xff);
_key[6] = (byte)(~_eepromUID[5] & 0xff);
_key[7] = (byte)(~_keyFragment[3] & 0xff);
_key[8] = (byte)(~machine_number[7] & 0xff);
_key[9] = (byte)(~machine_number[5] & 0xff);
_key[10] = (byte)(~machine_number[2] & 0xff);
_key[11] = (byte)(~_eepromUID[1] & 0xff);
_key[12] = (byte)(~_eepromUID[4] & 0xff);
_key[13] = (byte)(~_keyFragment[4] & 0xff);
_key[14] = (byte)(~_keyFragment[5] & 0xff);
_key[15] = (byte)(~_eepromUID[6] & 0xff);
_key[16] = (byte)(~_keyFragment[6] & 0xff);
_key[17] = (byte)(~machine_number[0] & 0xff);
_key[18] = (byte)(~machine_number[6] & 0xff);
_key[19] = (byte)(~_eepromUID[0] & 0xff);
_key[20] = (byte)(~machine_number[4] & 0xff);
_key[21] = (byte)(~_keyFragment[7] & 0xff);
_key[22] = (byte)(~_eepromUID[2] & 0xff);
machine_number = null;
}