/* Process description:
* 1) Insert data
* 2) Insert size of data (4 bytes int)
* 3) Insert packet type (4 bytes int)
* 4) Insert crc32 of type+size+data (4 bytes uint)
* 5) Insert empty IV (16 bytes string)
*/
public static byte[] CreatePacket(byte[] serializedPacket, int packetType)
{
byte[] packetBytes = serializedPacket; //Insert data
packetBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(packetBytes.Length), packetBytes); //+size
packetBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(packetType), packetBytes); //+type
packetBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(Crc32Operation.ComputeCRC32(packetBytes)), packetBytes); //+crc
packetBytes = InsertBytesAtIndex(0, Encoding.ASCII.GetBytes(EmptyIV), packetBytes); //+empty iv
return(packetBytes);
}
public static bool IsValidCRC32(uint crc, byte[][] packetParts)
{
byte[] total = new byte[packetParts.Sum(parts => parts.Length)];
int offset = 0;
foreach (byte[] part in packetParts)
{
Array.Copy(part, 0, total, offset, part.Length);
offset += part.Length;
}
return(crc == Crc32Operation.ComputeCRC32(total));
}
/* Process description:
* 1) Insert data
* 2) Insert size of data (4 bytes int)
* 3) Insert packet type (4 bytes int)
* 4) Insert crc32 of type+size+data (4 bytes uint)
* 5) Encrypt entire array w/ AES256
* 6) Insert size of encrypted data (4 bytes int)
* 7) Insert IV (16 bytes string)
*/
public static byte[] CreateEncryptedPacket(byte[] serializedPacket, int packetType, byte[] key, byte[] iv)
{
byte[] finalBytes = serializedPacket; //Insert data
finalBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(finalBytes.Length), finalBytes); //+size
finalBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(packetType), finalBytes); //+type
finalBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(Crc32Operation.ComputeCRC32(finalBytes)), finalBytes); //+crc
finalBytes = new Aes(256).Encrypt(finalBytes, key, iv); //+enc
#if DEBUG
Console.WriteLine($"Encrypted data: {BitConverter.ToString(finalBytes)}");
#endif
finalBytes = InsertBytesAtIndex(0, BitConverter.GetBytes(finalBytes.Length), finalBytes); //+encSize
finalBytes = InsertBytesAtIndex(0, iv, finalBytes); //+iv
return(finalBytes);
}
